TY - CONF A1 - Marano, Roberto T1 - Antimicrobial coatings: modes of action, microbiological efficacy testing, and resistance evolution N2 - Antimicrobial coatings and materials on high touch surfaces can provide additional level of protection to periodic disinfection cycles by reducing bacterial loads. However, different coatings and materials assert their antimicrobial activity in different ways, and it is not clear whether they could pose detrimental selective pressure towards antibiotic-resistant bacteria. This talk elucidates modes of actions and current knowledge gaps in testing antimicrobial resistance on antimicrobial surfaces.” T2 - STOP Antimicrobial Coating Conference CY - Mons, Belgium DA - 05.12.2024 KW - Antimicrobial-resistance KW - Surface antimicrobial testing KW - Materials testing PY - 2025 AN - OPUS4-64566 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Marano, Roberto T1 - A Customizable Procedure for Predicting Antibiotic Resistance Selection on Novel Antimicrobial Coatings N2 - This presentation introduceda new methodological approach developed to test antimocrobials implemented on high touch surfaces, inlcuding preliminary results on its use on reference antimicrobial materials. The seminar was organized by the 'Fast-real' project, funded by the Horizon Europe (project ID: 101159721). T2 - Novel strategies and considerations in fighting pathogens CY - Tartu, Estonia DA - 16.06.2025 KW - Antimicrobial-resistance KW - Surface antimicrobial testing KW - Materials testing PY - 2025 AN - OPUS4-64568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mezera, Marek T1 - Bacterial adhesion on femtosecond laser-induced periodic surface structures N2 - Biofilm formation in industrial or medical settings is usually unwanted and leads to serious health problems and high costs. Inhibition of initial bacterial adhesion prevents biofilm formation and is, therefore, a major mechanism of antimicrobial action of surfaces. Surface topography largely influences the interaction between bacteria and surfaces which makes topography an ideal base for antifouling strategies and eco-friendly alternatives to chemical surface modifications. Femtosecond laser-processing was used to fabricate sub-micrometric surface structures on silicon and stainless steel for the development of antifouling topographies on technical materials. T2 - Future Tech Week 2020 CY - Online meeting DA - 21.09.2020 KW - Laser-induced periodic surface structures (LIPSS) KW - Bacterial adhesion KW - Biofilm growth KW - Structural color KW - Femtosecond laser processing PY - 2020 UR - http://futuretechweek.fetfx.eu/wp-content/uploads/gravity_forms/2-5432af7ecff9e0243d7383ab3f931ed3/2020/09/BioCombs4Nanofibers_Poster-for-Future_Tech_Week_2020_08-09-2020_with_Reprint-permission_for_upload.pdf AN - OPUS4-51233 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mezera, Marek T1 - Influence of the pulse repetition rate on the chemical and morphological properties of laser generated surface structures N2 - Inter-pulse accumulation of heat could affect the chemical and morphological properties of the laser processed material surface. Hence, the laser pulse repetition rate may restrict the processing parameters for specific laser-induced surface structures. In this study, the evolution of various types of laser-induced micro- and nanostructures at various laser fluence levels, effective number of pulses and at different pulse repetition rates (1 – 400 kHz) are studied for common metals/alloys (e.g. steel or titanium alloy) irradiated by near-infrared ultrashort laser pulses (925 fs, 1030 nm) in air environment. The processed surfaces were characterized by optical and scanning electron microscopy (OM, SEM), energy dispersive X-ray spectroscopy (EDX) as well as time of flight secondary ion mass spectrometry (TOF-SIMS). The results show that not only the surface morphology could change at different laser pulse repetition rates and comparable laser fluence levels and effective number of pulses, but also the surface chemistry is altered. Consequences for medical applications are outlined. T2 - European Materials Research Society Spring 2021 Meeting CY - Online meeting DA - 31.05.2021 KW - Laser-induced pariodic surface structures KW - LIPSS PY - 2021 AN - OPUS4-52778 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mirabella, Francesca T1 - ToF-SIMS as a new tool for nano-scale investigation of ps-laser-generated surface structures on titanium substrates N2 - In recent years, the fabrication of laser-generated surface structures on metals such as titanium surfaces have gained remarkable interests, being technologically relevant for applications in optics, medicine, fluid transport, tribology, and wetting of surfaces. The morphology of these structures, and so their chemistry, is influenced by the different laser processing parameters such as the laser fluence, wavelength, pulse repetition rate, laser light polarization type and direction, angle of incidence, and the effective number of laser pulses per beam spot area. However, the characterization of the different surface structures can be difficult because of constraints regarding the analytical information from both depth and the topographic artifacts which may limit the lateral and depth resolution of elemental distributions as well as their proper quantification. A promising technique to investigate these structures even at the nano-scale is Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), a very surface sensitive technique that at the same time allows to perform depth-profiling, imaging and 3D-reconstruction of selected ion-sputter fragment distributions on the surface. In this study we combine chemical analyses such as Energy Dispersive X-ray spectroscopy (EDX) and high-resolution scanning electron microscopy (SEM) analyses with ToF-SIMS to fully characterize the evolution of various types of laser-generated micro- and nanostructures formed on Ti and Ti alloys at different laser fluence levels, effective number of pulses and at different pulse repetition rates (1 – 400 kHz), following irradiation by near-infrared ultrashort laser pulses (925 fs, 1030 nm) in air environment or under argon gas flow. We show how this combined surface analytical approach allows to evaluate alteration in the surface chemistry of the laser-generated surface structures depending on the laser processing parameters and the ambient environment. T2 - European Materials Research Society (EMRS) Fall Meeting 2021 CY - Online meeting DA - 20.09.2021 KW - ToF SIMS KW - Nano characterization PY - 2021 AN - OPUS4-53366 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Misra, Archismita T1 - Polyoxometalate Ionic Liquids (POM-ILs) as Protective Coatings for CulturalHeritage against Acid Corrosion and Biodeterioration N2 - Corrosion of stone by acid rain anddeterioration from microbial biofilmsare challenges pertinent worldwide forindustrial or residential buildings as wellas cultural heritage artefacts, like statuesor historic buildings. One mitigationoption might be the use of thintransparent films of polyoxometalate-based ionic liquids (POM-ILs). In thisregard, different limestone samples werecoated with hydrophobic, acid resistantPOM-ILs which also have biocidalproperties.1 Exposure of the samples tosimulated acid rain showed negligiblecorrosion compared to the significantdeterioration of unprotected samples(Fig 1. Left). In addition, the biocidalproperties of the POM-ILs suppress theformation of biofilms on coated stoneslabs. The coating is mechanically stableand is not removed even by harshmechanical and chemical treatment.Following studies successfully exploredthe effectiveness of the coating againstlampenflora growing in the PommeryChampagne cellar 2 (Fig 1. Right); andthe long-term performance of POM-ILsunder outdoor environmental conditions3. So, POM-ILs are already proven topossess remarkable anticorrosion andantimicrobial properties against aerobicmicroorganisms and being water-insoluble, they don’t get leached intoaquatic ecosystem, which is extremelybeneficial from an environmentalsustainability and toxicological point ofview. The current project aims tocontinue the journey on protecting thecultural heritage, shifting focus fromstones to metals and employ functionalPOM-IL nanocoatings to prevent MIC(Microbiologically Influenced Corrosion)of cultural heritage artefacts made ofmetal or metal alloy like carbon steel,brass, cast iron or bronze. Performanceof both the coating materials and coatingtechniques via optimization of theadhesion of the nanocoating on themetallic surface on the corrosion rateand corrosion products in the MICcaused by anaerobic microorganismslike methanogenic archaea or SulphateReducing Bacteria (SRB) would betested. The objective is to establishPOM-ILs as efficient environmentallysustainable nanocoating materialsagainst biocorrosion citing the already published success stories; and sketch theongoing endeavours and prospects ofthese very efficient candidates in thecontext of MIC mitigation. T2 - Mitigation of Microbiologically InfluencedCorrosion: Towards Scientific &Industrial Standardization (MIC-STAND) CY - Lisbon, Portugal DA - 24.07.2024 KW - Microbiologically influenced corrosion (MIC) KW - Polyoxometalate Ionic Liquid KW - Nanocoating KW - Cultural heritage PY - 2024 AN - OPUS4-64575 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Misra, Archismita T1 - Polyoxometalate Ionic Liquids (POMILs) as Protective Coatings for Cultural Heritage Against Acid Corrosion and Biodeterioration N2 - Corrosion of stone by acid rain anddeterioration from microbial biofilms are challenges worldwide present forindustrial or residential buildings as wellas cultural heritage, like statues orhistoric buildings. One option is the useof thin transparent films ofpolyoxometalate-based ionic liquids(POM-ILs). Stone samples were coatedwith hydrophobic, acid resistant POM-ILs which also have biocidal properties.1Exposure of the samples to simulatedacid rain showed negligible corrosioncompared to the significant deteriorationof unprotected samples (Fig 1. Left). Inaddition, the biocidal properties of thePOM-ILs suppress the formation ofbiofilms on coated stone slabs. Thecoating is mechanically stable and is notremoved even by harsh mechanical andchemical treatment. Following studiessuccessfully explored the effectiveness ofthe coating against lampenflora growingin the Pommery Champagne cellar 2 (Fig1. Right); and the long-termperformance of POM-ILs under outdoorenvironmental conditions 3. So, POM-ILs are already proven to possessremarkable anticorrosion andantimicrobial properties against aerobicmicroorganisms and being water-insoluble, they don’t get leached intoaquatic ecosystem, which is extremelybeneficial from an environmentalsustainability and toxicological point ofview. The current project aims tocontinue the journey on protecting thecultural heritage, shifting focus fromstones to metals and employ functionalPOM-IL nanocoatings to prevent MIC(Microbiologically Influenced Corrosion)of cultural heritage artefacts made ofmetal or metal alloy like carbon steel,brass, cast iron or bronze. Performanceof both the coating materials and coatingtechniques via optimization of theadhesion of the nanocoating on themetallic surface on the corrosion rateand corrosion products in the MICcaused by anaerobic microorganismslike methanogenic archaea or SulphateReducing Bacteria (SRB) would betested. The objective would be toestablish POM-ILs as efficientenvironmentally sustainablenanocoating materials againstbiocorrosion citing the already publishedsuccess stories; and sketch the ongoingendeavours and prospects of these veryefficient candidates in the context ofbiocorrosion T2 - International Biodeterioration and Biodegradation Symposium CY - Berlin, Germany DA - 09.09.2024 KW - Microbiologically influenced corrosion (MIC) KW - Polyoxometalate Ionic Liquid KW - Nanocoating KW - Cultural heritage PY - 2024 AN - OPUS4-64576 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Misra, Archismita T1 - Polyoxometalate Ionic Liquids as Protective Coatings for Industrial Infrastructure and Cultural Heritage against Microbiologically Influenced Corrosion (MIC) N2 - Corrosion of stone and metal due to acid rain and biodeterioration poses significant challenges for industrial and residential infrastructure, as well as cultural heritage, including statues and historical artefacts. A promising mitigation strategy involves thin, transparent films of polyoxometalate-based ionic liquids (POM-ILs) as chemical shields. Stone samples coated with acid-resistant, biocidal POM-ILs exhibited negligible corrosion when exposed to simulated acid rain, in stark contrast to the severe deterioration of unprotected samples. Additionally, their biocidal properties effectively prevent biofilm formation on coated surfaces. Following studies successfully explored the effectiveness of the coating against lampenflora growing in the Pommery Champagne cellar; and the long-term performance of POM-ILs under outdoor environmental conditions. So, POM-ILs have already demonstrated remarkable anticorrosion and antimicrobial properties against aerobic microorganisms and, being water-insoluble, do not leach into aquatic ecosystem. The current research project repurposes the POM-ILs, extending their application to metals, specifically targeting microbiologically influenced corrosion (MIC) in cultural heritage artefacts made of brass, carbon steel, cast iron, and bronze. This involves optimizing nanocoating adhesion to the metal surface and evaluating its protective efficacy against MIC caused by anaerobic microorganisms such as methanogenic archaea and sulfate reducing bacteria (SRB). This presentation will highlight POM-ILs as sustainable, high-performance nanocoatings for biocorrosion mitigation. It will showcase published success stories, discuss ongoing research and proof-of-concept results, and explore future prospects for these advanced materials in safeguarding metal infrastructure and artefacts across different industrial sectors as well as in the context of cultural heritage conservation. T2 - 10th International symposium on applied microbiology and molecular biology in oil systems (ISMOS10) CY - Nashville, Tennessee, USA DA - 11.08.2025 KW - Polyoxometalates KW - Corrosion KW - Microbiologically Influenced Corrosion KW - Ionic Liquid PY - 2025 AN - OPUS4-64548 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Misra, Archismita T1 - Polyoxometalate Ionic Liquids as Protective Coatings for Industrial Infrastructure and Cultural Heritage against Microbiologically Influenced Corrosion (MIC) N2 - Corrosion of stone and metal due to acid rain and biodeterioration poses significant challenges for industrial and residential infrastructure, as well as cultural heritage, including statues and historical artefacts. A promising mitigation strategy involves thin, transparent films of polyoxometalate-based ionic liquids (POM-ILs) as chemical shields. Stone samples coated with acid-resistant, biocidal POM-ILs exhibited negligible corrosion when exposed to simulated acid rain, in stark contrast to the severe deterioration of unprotected samples. Additionally, their biocidal properties effectively prevent biofilm formation on coated surfaces. Following studies successfully explored the effectiveness of the coating against lampenflora growing in the Pommery Champagne cellar; and the long-term performance of POM-ILs under outdoor environmental conditions. So, POM-ILs have already demonstrated remarkable anticorrosion and antimicrobial properties against aerobic microorganisms and, being water-insoluble, do not leach into aquatic ecosystem. The current research project repurposes the POM-ILs, extending their application to metals, specifically targeting microbiologically influenced corrosion (MIC) in cultural heritage artefacts made of brass, carbon steel, cast iron, and bronze. This involves optimizing nanocoating adhesion to the metal surface and evaluating its protective efficacy against MIC caused by anaerobic microorganisms such as methanogenic archaea and sulfate reducing bacteria (SRB). This presentation will highlight POM-ILs as sustainable, high-performance nanocoatings for biocorrosion mitigation. It will showcase published success stories, discuss ongoing research and proof-of-concept results, and explore future prospects for these advanced materials in safeguarding metal infrastructure and artefacts across different industrial sectors as well as in the context of cultural heritage conservation. T2 - Euro-MIC COST Action - Closing Workshop Conference CY - Horsens, Denmark DA - 17.09.2025 KW - Polyoxometalates KW - Corrosion KW - Microbiologically Influenced Corrosion KW - Ionic Liquid PY - 2025 AN - OPUS4-64549 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - The disinfectant glutaraldehyde induces antibiotic tolerance underpinned by phenotypic heterogeneity and transcriptome remodeling N2 - Glutaraldehyde is widely used as a disinfectant and preservative, but little is known about its effects on bacterial susceptibility to antibiotics and the selection of tolerant phenotypes. We found that short-term exposure to sub-inhibitory levels of glutaraldehyde makes E. coli resistant to high doses of bactericidal antibiotics from different classes. This tolerance is associated with delayed, heterogeneous regrowth dynamics and global transcriptome remodeling. We identified over 1200 differentially expressed genes, including those related to antibiotic efflux, metabolic processes, and the cell envelope. The cells entered a disrupted state likely due to the unspecific mode-of-action of glutaraldehyde. Despite this unregulated response, we identified several differentially expressed genes not previously associated with antibiotic tolerance or persistence that induce antibiotic tolerance when overexpressed alone. These findings highlight how the unspecific mode-of-action of disinfectants can make bacteria temporarily resistant to antibiotics. They have implications for settings where disinfectants and antibiotics are used in close proximity, such as hospitals and animal husbandry, and for the selection dynamics of tolerant pheno- and genotypes in fluctuating environments where microorganisms are exposed to these substances, such as sewage systems. A trade-off arises from overcoming the disrupted state as quickly as possible and maintaining antibiotic tolerance. T2 - µClub Seminar Series CY - Berlin, Germany DA - 26.05.2023 KW - Glutaraldehyde KW - Biocides KW - Tolerance KW - Bacteria KW - Disinfection KW - Heterogeneity PY - 2023 AN - OPUS4-58031 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - The disinfectant glutaraldehyde induces antibiotic tolerance underpinned by a Disrupted Cellular State and Heterogenous Regrowth Dynamics N2 - Glutaraldehyde is widely used as a disinfectant and preservative, but little is known about its effects on bacterial susceptibility to antibiotics and the selection of tolerant phenotypes. We found that short-term exposure to sub-inhibitory levels of glutaraldehyde makes E. coli resistant to high doses of bactericidal antibiotics from different classes. This tolerance is associated with delayed, heterogeneous regrowth dynamics and global transcriptome remodeling. We identified over 1200 differentially expressed genes, including those related to antibiotic efflux, metabolic processes, and the cell envelope. The cells entered a disrupted state likely due to the unspecific mode-of-action of glutaraldehyde. Despite this unregulated response, we identified several differentially expressed genes not previously associated with antibiotic tolerance or persistence that induce antibiotic tolerance when overexpressed alone. These findings highlight how the unspecific mode-of-action of disinfectants can make bacteria temporarily resistant to antibiotics. They have implications for settings where disinfectants and antibiotics are used in close proximity, such as hospitals and animal husbandry, and for the selection dynamics of tolerant pheno- and genotypes in fluctuating environments where microorganisms are exposed to these substances, such as sewage systems. A trade-off arises from overcoming the disrupted state as quickly as possible and maintaining antibiotic tolerance. T2 - Molecular Mechanisms in Evolution (GRS) Gordon Research Seminar CY - Easton, Massachusetts, USA DA - 24.06.2023 KW - Glutaraldehyde KW - Biocides KW - Tolerance KW - Bacteria KW - Disinfection KW - Heterogeneity KW - Antibiotics KW - AMR PY - 2023 AN - OPUS4-58032 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - The interplay between biocides, phenotypic heterogeneity and resistance evolution N2 - An overview of the interplay between biocides, phenotypic heterogeneity and resistance evolution presented at the University Wroclaw. T2 - Invited seminar at the Department of Molecular Microbiology CY - Wroclaw, Poland DA - 08.04.2024 KW - Disinfectants KW - Biocide resistance KW - Phenotypic heterogeneity KW - Evolution PY - 2024 AN - OPUS4-61173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Biocides and phenotypic heterogeneity N2 - An overview of our findings regarding the interplay between phenotypic heterogeneity in bacteria and biocides. T2 - One Health and Antimicrobial Resistance CY - Berlin, Germany DA - 29.01.2024 KW - Biocides KW - Phenotypic heterogeneity KW - Biocide resistance PY - 2024 AN - OPUS4-61174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - EVOCIDE: Preserving disinfectant efficacy by predicting evolution: exposing the principles of disinfectant survival and adaptation in bacteria N2 - Presentation of the EVOCIDE research proposal work programme.EVOCIDE seeks to gain a systems level understanding of disinfectant survival and evolution in bacteria. T2 - Joint Group Seminar Rolff-McMahon-Armitage-Steiner CY - Berlin, Germany DA - 20.12.2023 KW - Disinfectants KW - Evolution KW - Microbiology KW - Bacteria KW - Biocides PY - 2023 AN - OPUS4-59224 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - ALEE-AMC: Bacterial resistance evolution towards antimicrobial surfaces and development of a standardized test N2 - Background: Antimicrobial surfaces and coatings (AMCs) are important to protect man-made structures from biodeterioration and biodegradation. Advances in nano-structuring methods hold the promise of a new generation of AMCs. However, the evolution and selection of bacterial resistance to AMCs may threaten their efficacy in the long term. Therefore, according to the EU Biocidal Products Regulation, the risk of resistance development upon exposure to AMCs must be evaluated during product authorization. The same applies to the development of cross-resistances to other substances, for instance biocides and antibiotics. However, no standardized method exists to assess the risk of resistance and cross-resistance development upon exposure to AMCs during the authorization process. Objectives: • To develop a standardizable adaptive laboratory evolution experiment to be performed on AMCs (ALEE-AMC) • To assess performance and robustness of ALEE-AMC in a round robin test, using a copper AMC as reference • To uncover the mechanisms underlying evolution of resistance to copper AMC Materials & Methods: ALEE-AMC was developed based on an approved standard to determine the efficacy of antimicrobial surfaces (ISO 22196). ALEE-MC was performed on an antimicrobial copper surface as reference material and Escherichia coli as model organism. A round robin test was conducted with six participants to evaluate the reproducibility and applicability of ALEE-AMC. Evolved E. coli populations from the round robin partners were collected and subjected to phenotypic (antimicrobial susceptibility testing, ISO 22196) and genotypic (whole genome sequencing) characterization at BAM. Results: The results of the ALEE-AMC round robin test indicate that repeated exposure to copper can select for reduced copper susceptibility. However, failure of individual E. coli lineages to adapt to the copper surfaces was also observed. Evolved E. coli exhibited increased survival upon exposure to copper surfaces. Adaptation to copper did not induce cross-resistance to antibiotics. Whole genome sequencing of the evolved E. coli revealed high diversity of mutations among individual evolved strains, indicating the existence of multiple, underexplored evolutionary pathways towards increased survival of antimicrobial copper surfaces. Conclusion & Significance: ALEE-AMC offers a standardizable platform to assess the risk of resistance development towards novel and existing AMCs. Specifically, using ALEE-AMC in a round robin test, insights into evolvable survival mechanisms to copper AMCs have been gained. These mechanistic insights may be exploited to prevent the evolution against copper AMCs. In future steps, criteria need to be defined to provide guidelines for the authorization of AMCs based on the outcomes of ALEE-AMC T2 - International Biodeterioration and Biodegradation Symposium, Berlin, Germany CY - Berlin, Germany DA - 09.09.2024 KW - Biocides KW - Antimicrobial surfaces KW - Resistance KW - Evolution KW - Standardized test PY - 2024 AN - OPUS4-61176 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Bacterial resistance evolution on antimicrobial surfaces: Mechanistic insights from a standardizable method N2 - Introduction: Antimicrobial surfaces and coatings (AMCs) are important to prevent the spread of pathogens, especially in hygiene-sensitive areas. However, the evolution and selection of bacterial resistance to AMCs may threaten their efficacy in the long term. In addition, resistance evolution to AMCs may pose the risk for the development of cross-resistance to antibiotics. The assessment of unacceptable resistance risks during the authorization of AMCs is hampered by the lack of standardized test methods that quantify the adaptability of exposed bacteria to AMCs. Objectives: • To develop a standardizable method to determine resistance evolution of bacteria on AMCs (ALEE-AMC) • To assess performance and robustness of ALEE-AMC in a ring trial • To uncover the mechanisms underlying evolution of resistance to a metallic copper AMC • To use ALEE-AMC to assess the evolution of resistance on a novel, nano-particle-based AMC Methods: ALEE-AMC was developed based on an international standard to determine the efficacy of antimicrobial surfaces (ISO 22196). In the ALEE-AMC test, adaptive laboratory evolution is conducted by repeated cycles of AMC exposure and re-growth of surviving cells, selecting for increased survival, followed by isolation of evolved clones. Metallic copper was used as a reference AMC and Escherichia coli as a model microorganism in the ring trial. Evolved E. coli populations from the ring trial partners were subjected to phenotypic (antimicrobial susceptibility testing, ISO 22196) and genotypic (whole genome sequencing) characterization. ALEE-AMC will be used to assess the evolution of resistance on a novel, nano-particle-based AMC currently under development. Findings: The results of the ALEE-AMC ring trial show that repeated exposure to a metallic copper AMC can reproducibly select for reduced copper susceptibility in individual evolutionary lineages across ring trial participants. However, failure to adapt in individual lineages was also observed in all trials. Isolated evolved E. coli clones exhibited increased survival upon exposure to copper surfaces. Adaptation to copper did not induce cross-resistance to antibiotics because the antibiotic susceptibility of copper-adapted clones did not increase above the clinical breakpoint. Whole genome sequencing of the evolved E. coli revealed a high diversity of mutations, including mutations in genes involved in survival to antibiotics. These results indicate the existence of multiple, underexplored evolutionary pathways towards increased survival of antimicrobial copper surfaces. Conclusion: ALEE-AMC offers a standardizable platform to assess the risk of resistance development towards novel and existing AMCs, including nano-particle-based and metallic copper AMCs. Specifically, using ALEE-AMC provided insights into evolvable survival mechanisms to copper AMCs and its consequences for antimicrobial resistance. T2 - FEMS MICRO 2025 CY - Mailand, Italy DA - 14.07.2025 KW - Biocides KW - Antimicrobial surfaces KW - Biocide resistance KW - Standardization KW - ISO 22196 KW - Evolution PY - 2025 AN - OPUS4-63837 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Phenotypic heterogeneity in bacterial lag times and antibiotic tolerance induced by the disinfectant glutaraldehydePhenotypic heterogeneity in bacterial lag times and antibiotic tolerance induced by the disinfectant glutaraldehyde N2 - Phenotypic heterogeneity in clonal bacterial populations can be considered a preliminary stage of functional differentiation, which may increase population fitness in fluctuating environments. Here, we investigated how transient exposure of clonal bacterial populations to residual amounts of a commonly used disinfectant, glutaraldehyde (GTA), induces phenotypic heterogeneity, ensuring survival of the population upon sudden challenge with high doses of antibiotics. Using the ScanLag system, we found that exposure to GTA resulted in wide lag-time distributions across different bacterial isolates of E. coli, S. aureus, and P. aeruginosa. Importantly, this was associated with elevated levels of survival (i.e. tolerance) towards lethal doses of antibiotics. As revealed by RNAseq in E. coli, GTA exposure caused global transcriptome remodeling, with more than 1200 differentially expressed genes of diverse biological functions. Several of these genes that were not previously associated with antibiotic tolerance or persistence induced, when overexpressed alone, antibiotic tolerance without showing a lag phenotype. This suggests that exposure to GTA induces unspecific, lag-dependent and specific, lag-independent tolerance to antibiotics in clonal bacterial populations. These findings have implications for 1.) settings where disinfectants and antibiotics are used in close proximity, such as hospitals and animal husbandry, and 2.) for the selection dynamics of tolerant pheno- and genotypes in fluctuating environments because of the trade-off that arises from exiting lag and resuming growth as fast as possible and maintaining antibiotic tolerance. This trade-off may be weakened by phenotypically heterogeneous clonal populations as induced by GTA. T2 - FAST REAL Project Meeting Tartu CY - Tartu, Estonia DA - 16.06.2025 KW - Biocides KW - Biocide resistance KW - Phenotypic heterogeneity KW - Glutaraldehyde KW - Disinfectants PY - 2025 AN - OPUS4-63834 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Evolution and mechanistic basis of disinfectant tolerance in E. coli N2 - Disinfectants are important to provide hygiene in sensitive areas, to prevent the spread of infections and to preserve materials from biodeterioration. Bacteria can survive disinfection through phenotypic and genotypic adaptation. Phenotypic heterogeneity may be linked to the ability to evolve disinfectant tolerance. The genetic factors which determine the survival of disinfection remain largely unknown. Here, we investigate the effects of phenotypic heterogeneity on the evolvability of disinfectant tolerance. Furthermore, using a whole-genome CRISPRi-library, we uncover genetic determinants that are important for the survival of disifenction. T2 - µClub Seminar Berlin CY - Berlin, Germany DA - 23.05.2025 KW - Biocides KW - Heterogeneity KW - Biocide resistance KW - Evolution KW - Disinfectants PY - 2025 AN - OPUS4-63833 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Heterogeneous tolerance to biocides and its consequences for the evolution of antimicrobial resistance N2 - The exposure to antimicrobial substances drives the evolution of antimicrobial resistance (AMR). Biocides are antimicrobials used as disinfectants, antiseptics and preservatives. They find application on a large scale in the industrial and medical sector, but also in private households. In terms of mass, the worldwide use of biocides exceeds that of antibiotics. Thus, despite their important role in preventing the spread of pathogens, due to their ubiquity, biocides are suspected to be drivers of the antimicrobial resistance crisis. In our work we try to understand how biocides contribute to the emergence of AMR, what the underlying adaptation principles and mechanisms are and how they compare to those found for antibiotics. Here, I present results which demonstrate that phenotypic heterogeneity in E. coli, namely the formation of tolerant persister cells, can enable the survival of disinfection and consequentially facilitate the evolution of AMR. Using experimental evolution that selects for tolerance, we find that mutations in lipid A biosynthesis arise following periodic treatment with benzalkonium chloride (BAC), a widely used disinfectant. BAC tolerance is associated with additional, diverse mutations as well as changes in the susceptibility to antibiotics from different classes and changes in motility and biofilm formation, suggesting extensive regulatory re-wiring in the evolved clones. Remarkably, we find that fitness costs (growth rate reduction) incurred by BAC tolerance are alleviated in the presence of antibiotics. These findings demonstrate the complexity underlying the adaptation to antimicrobials and highlight the links between persistence to disinfectants and resistance evolution to antimicrobials. T2 - 4th VAAM discussion meeting 'Microbial Cell Biology' CY - Berlin, Germany DA - 09.10.2022 KW - Persistence KW - Biocides KW - Evolution KW - Disinfection KW - Biocide tolerance KW - Heterogeneity PY - 2022 AN - OPUS4-55958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Persistence against benzalkonium chloride promotes rapid evolution of tolerance under periodic disinfection N2 - A presentation given at the VAAM conference 2022, summarizing our findings published in the research paper "Persistence against benzalkonium chloride promotes rapid evolution of tolerance under periodic disinfection" T2 - Annual conference of the association for general and applied microbiology (VAAM) 2022 CY - Düsseldorf, Germany DA - 21.02.2022 KW - Persistence KW - Biocides KW - Evolution KW - Cross-resistance KW - Biocide tolerance KW - Disinfection PY - 2022 AN - OPUS4-54437 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Phenotypic heterogeneity in bacterial lag times and antibiotic tolerance induced by the disinfectant glutaraldehyde N2 - Phenotypic heterogeneity in clonal bacterial populations can be considered a preliminary stage of functional differentiation, which may increase population fitness in fluctuating environments. Here, we investigated how transient exposure of clonal bacterial populations to residual amounts of a commonly used disinfectant, glutaraldehyde (GTA), induces phenotypic heterogeneity, ensuring survival of the population upon sudden challenge with high doses of antibiotics. Using the ScanLag system, we found that exposure to GTA resulted in wide lag-time distributions across different bacterial isolates of E. coli, S. aureus, and P. aeruginosa. Importantly, this was associated with elevated levels of survival (i.e. tolerance) towards lethal doses of antibiotics. As revealed by RNAseq in E. coli, GTA exposure caused global transcriptome remodeling, with more than 1200 differentially expressed genes of diverse biological functions. Several of these genes that were not previously associated with antibiotic tolerance or persistence induced, when overexpressed alone, antibiotic tolerance without showing a lag phenotype. This suggests that exposure to GTA induces unspecific, lag-dependent and specific, lag-independent tolerance to antibiotics in clonal bacterial populations. These findings have implications for 1.) settings where disinfectants and antibiotics are used in close proximity, such as hospitals and animal husbandry, and 2.) for the selection dynamics of tolerant pheno- and genotypes in fluctuating environments because of the trade-off that arises from exiting lag and resuming growth as fast as possible and maintaining antibiotic tolerance. This trade-off may be weakened by phenotypically heterogeneous clonal populations as induced by GTA. T2 - 1st International Conference on Emergent Functions of Bacterial Multicellularity CY - Berlin, Germany DA - 06.01.2025 KW - Disinfectants KW - Biocides KW - Phenotypic heterogeneity PY - 2025 AN - OPUS4-62462 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - The disinfectant glutaraldehyde induces antibiotic tolerance N2 - Glutaraldehyde is widely used as a disinfectant and preservative, but little is known about its effects on bacterial susceptibility to antibiotics and the selection of tolerant phenotypes. We found that short-term exposure to sub-inhibitory levels of glutaraldehyde makes E. coli resistant to high doses of bactericidal antibiotics from different classes. This tolerance is associated with delayed, heterogeneous regrowth dynamics and global transcriptome remodeling. We identified over 1200 differentially expressed genes, including those related to antibiotic efflux, metabolic processes, and the cell envelope. The cells entered a disrupted state likely due to the unspecific mode-of-action of glutaraldehyde. Despite this unregulated response, we identified several differentially expressed genes not previously associated with antibiotic tolerance or persistence that induce antibiotic tolerance when overexpressed alone. These findings highlight how the unspecific mode-of-action of disinfectants can make bacteria temporarily resistant to antibiotics. They have implications for settings where disinfectants and antibiotics are used in close proximity, such as hospitals and animal husbandry, and for the selection dynamics of tolerant pheno- and genotypes in fluctuating environments where microorganisms are exposed to these substances, such as sewage systems. A trade-off arises from overcoming the disrupted state as quickly as possible and maintaining antibiotic tolerance. T2 - Gordon Research Conference - Molecular Mechanisms in Evolution CY - Easton, Massachusetts, United States DA - 25.06.2023 KW - Glutaraldehyde KW - Biocides KW - Tolerance KW - Bacteria KW - Disinfection KW - Heterogeneity KW - Antibiotics PY - 2023 AN - OPUS4-58033 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - The disinfectant glutaraldehyde induces antibiotic tolerance underpinned by Phenotypic Heterogeneity and transcriptome remodeling N2 - Glutaraldehyde (GTA) is commonly used to disinfect medical equipment, in animal husbandry and in hydraulic fracturing. Its wide use bears the risk that microorganisms in different environments are exposed to potentially non-lethal doses of glutaraldehyde. To date, little is known about the effects of glutaraldehyde on the susceptibility of bacteria to antibiotics and its role in the selection of tolerant phenotypes. Objectives • To determine the effect of glutaraldehyde exposure on the survival of E. coli, S. aureus and P. aeruginosa to antibiotics • To find the mechanistic basis for antibiotic tolerance upon glutaraldehyde exposure Materials & Methods Four bacterial isolates were exposed to sub-inhibitory glutaraldehyde. Antibiotic tolerance was determined by time-kill assays. Regrowth dynamics (lag times) were determined with ScanLag. E. coli was further investigated, using RNAseq to identify genes and processes involved in antibiotic tolerance. Mutants of candidate genes were screened for their antibiotic tolerance and heterogeneous target gene expression under stressed and unstressed conditions. Results Short-term exposure to sub-inhibitory levels of glutaraldehyde induced tolerance to high doses of bactericidal antibiotics. Tolerance to antibiotics was associated with highly heterogeneous regrowth dynamics and global transcriptome remodeling. Differentially expressed genes represented diverse biological functions and cellular components, including antibiotic efflux, metabolic processes, and the cell envelope. The heterogeneous regrowth dynamics and the diversity of the differentially expressed genes are likely related to the unspecific mode-of-action of glutaraldehyde. Among the many differentially expressed genes, several genes were identified that were not previously associated with antibiotic tolerance or persistence, which, when overexpressed alone, increased antibiotic tolerance. Conclusion Our results highlight how the big advantage of a disinfectant, its unspecific mode-of-action, can induce transient tolerance to antibiotics in bacteria. These findings have implications for 1.) settings where disinfectants and antibiotics are used in proximity, such as hospitals and animal husbandry, and 2.) for the selection dynamics of tolerant bacteria in fluctuating environments because of the trade-off that arises from overcoming the lag phase as fast as possible and maintaining antibiotic tolerance. T2 - VAAM Jahrestagung 2023 CY - Göttingen, Germany DA - 10.09.2023 KW - Glutaraldehyde KW - Disinfectants KW - Biocides KW - Antibiotics KW - Bacteria PY - 2023 AN - OPUS4-58439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - NBD-DDA: a tool to study biocide & disinfectant resistance mechanisms N2 - Quaternary ammonium compounds (QACs) are widely used as active agents in disinfectants, antiseptics, and preservatives. Despite being in use since the 1940s, there remain multiple open questions regarding their detailed mode-of-action and the mechanisms that can make bacteria less susceptible to QACs, including phenotypic heterogeneity. Goals To develop a fluorescent quaternary ammonium compound and to use it to investigate the mechanisms underlying QAC susceptibility in bacteria. Material & Methods A fluorescent quaternary ammonium compound, N-dodecyl-N,N-dimethyl-[2-[(4-nitro-2,1,3-benzoxadiazol-7-yl)amino]ethyl] azanium-iodide (NBD-DDA), was synthesized. Chemical structure and purity of NBD-DDA was confirmed by mass spectrometry and NMR spectroscopy. Antimicrobial activity against S. aureus, P. aeruginosa and E. coli was assessed by determination of minimum inhibitory concentrations and time-kill assays. Uptake, heterogeneity and efflux of NBD-DDA in wild-type and efflux-deficient mutants (ΔtolC) were determined, using flow cytometry and fluorometry. Sub-cellular localization of NBD-DDA was determined using confocal laser scanning microscopy. Results NBD-DDA was readily detected by flow cytometry and fluorescence microscopy with standard GFP/FITC-settings. NBD-DDA retained antimicrobial activity comparable to the structurally similar, widely used QAC benzalkonium chloride (BAC). Characteristic time-kill kinetics and increased tolerance of a BAC tolerant E. coli strain against NBD-DDA suggest that the mode of action of NBD-DDA is similar to that of BAC. NBD-DDA was preferentially localized to the cell envelope, which is a primary target of BAC and other QACs. Leveraging NBD-DDA‘s fluorescent properties, it was demonstrated that reduced cellular accumulation underlies BAC tolerance in a BAC tolerant E. coli strain and that NBD-DDA is subject to efflux mediated by TolC. Summary Overall, NBD-DDA’s antimicrobial activity, its fluorescent properties, and its ease of detection render it a powerful tool to study mechanisms of QAC susceptibility and mode-of-action in bacteria, both on the level of populations and single-cells. T2 - VAAM - Jahrestagung 2024 CY - Würzburg, Germany DA - 02.06.2024 KW - Biocides KW - Phenotypic heterogeneity PY - 2024 AN - OPUS4-61177 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Consequences of BAC tolerance for selection and evolution in the presence of antibiotics N2 - The exposure to antimicrobial substances drives the evolution of antimicrobial resistance. Biocides are antimicrobials used as disinfectants, antiseptics and preservatives. They find application on a large scale in the industrial and medical sector, but also in private households. In terms of mass, the worldwide use of biocides exceeds that of antibiotics. Thus, despite their important role in preventing the spread of pathogens, due to their ubiquity, biocides are suspected to be drivers of the antimicrobial resistance crisis. In our work at BAM we try to understand how biocides contribute to the emergence of AMR, what the underlying adaptation principles and mechanisms are and how they compare to those found for antibiotics. Within our group, I mainly focus on the following two questions: How does phenotypic heterogeneity in bacteria affect the ability to survive treatment with biocides? And what are the consequences of phenotypic heterogeneity for the evolution of resistance to biocides and antibiotics? I will share published and unpublished results which demonstrate that phenotypic heterogeneity can enable the survival of biocide treatment and, through this, facilitate the evolution of AMR. On the other hand, we find that adaptation to a biocide can unexpectedly impair the ability to evolve resistance against an antibiotic. T2 - FEMS summer school for postdocs 2022: Microbial Evolvability Mechanisms: Resistance, Biology, and Strategies to Defeat and Detect CY - Split, Croatia DA - 27.04.2022 KW - Disinfection KW - Biocides KW - Evolution KW - Resistance KW - Biocide tolerance PY - 2022 AN - OPUS4-54846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Persistence against benzalkonium chloride promotes rapid evolution of tolerance under periodic disinfection N2 - The exposure to antimicrobial substances drives the evolution of antimicrobial resistance (AMR). Biocides are antimicrobials used as disinfectants, antiseptics and preservatives. They find application on a large scale in the industrial and medical sector, but also in private households. In terms of mass, the worldwide use of biocides exceeds that of antibiotics. Thus, despite their important role in preventing the spread of pathogens, due to their ubiquity, biocides are suspected to be drivers of the antimicrobial resistance crisis. In our work we try to understand how biocides contribute to the emergence of AMR, what the underlying adaptation principles and mechanisms are and how they compare to those found for antibiotics. Here, I present results which demonstrate that phenotypic heterogeneity in E. coli, namely the formation of tolerant persister cells, can enable the survival of disinfection and consequentially facilitate the evolution of AMR. Using experimental evolution that selects for tolerance, we find that mutations in lipid A biosynthesis arise following periodic treatment with benzalkonium chloride (BAC), a widely used disinfectant. BAC tolerance is associated with additional, diverse mutations as well as changes in the susceptibility to antibiotics from different classes and changes in motility and biofilm formation, suggesting extensive regulatory re-wiring in the evolved clones. Remarkably, we find that fitness costs (growth rate reduction) incurred by BAC tolerance are alleviated in the presence of antibiotics. These findings demonstrate the complexity underlying the adaptation to antimicrobials and highlight the links between persistence to disinfectants and resistance evolution to antimicrobials. T2 - Bacterial Networks (BacNet22) CY - Sant Feliu de Guixols, Spanien DA - 04.09.2022 KW - Persistence KW - Biocides KW - evolution KW - disinfection KW - biocide tolerance PY - 2022 AN - OPUS4-55713 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Progress on STOP-project WP5 and WP6 at BAM N2 - An overview of the progress that has been made on testing of antimicrobial efficacy and method development in the STOP project at BAM. T2 - STOP project meeting 09/2024 CY - Bukarest, Romania DA - 18.09.2024 KW - Antimicrobial surfaces KW - ISO22196 PY - 2024 AN - OPUS4-61178 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas T1 - Phenotypic heterogeneity in disinfection: sources and consequences for antimicrobial resistance N2 - A summary of projects here at BAM which investigate the influence of phenotypic heterogeneity on the outcome of disinfection and the influence on antimicrobial resistance. This presentation was given in the Theory Seminar of the Quantitative and Theoretical Biology group of Prof. Oliver Ebenhöh at HHU Düsseldorf T2 - Theory Seminar in the Quantitative and Theoretical Biology group at HHU Düsseldorf CY - Düsseldorf, Germany DA - 24.02.2022 KW - Disinfection KW - Biocides KW - Heterogeneity KW - Resistance PY - 2022 AN - OPUS4-54442 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas A1 - Kanaris, Orestis A1 - Lewerenz, Dominique A1 - Gödt, Annett A1 - Schreiber, Frank T1 - Evolutionary implications of heterogeneous disinfectant tolerance N2 - Introduction: Effective disinfection is crucial to maintain hygiene and to prevent the spread of infections. Phenotypic heterogeneity in disinfection survival (i.e. tolerance) may result in failure of disinfection, which in turn may foster the evolution of resistance to both disinfectants and antibiotics. However, the consequences of phenotypic heterogeneity for disinfection outcome and resistance evolution are not well understood. Goal: This study investigates the impact of phenotypic heterogeneity on the survival and evolution of Escherichia coli during disinfection with six commonly used substances. Furthermore, the consequences of evolved disinfectant tolerance for antibiotic resistance evolution are studied. Materials & Methods: The extent of population heterogeneity during disinfection is derived by determining time-kill kinetics and analysis with mathematical modelling. The link between population heterogeneity and evolvability of disinfectant tolerance was assessed by laboratory evolution experiments under periodic disinfection. The ability of disinfectant tolerant strains to evolve antibiotic resistance is assessed by serial transfer experiments with increasing concentrations of different antibiotics and by whole genome sequencing. Results: Multi-modal time-kill kinetics in three of the six disinfectants suggest the presence of disinfectant-tolerant subpopulations (i.e. persister cells). Importantly, the ability and extent to evolve population-wide tolerance under periodic disinfection is related with the presence of persister cells and the level of phenotypic heterogeneity during disinfection. Interestingly, the probability of high-level resistance evolution to certain antibiotics is attenuated in disinfectant tolerant strains as compared to the sensitive ancestor. Whole-genome sequencing reveals epistatic interactions between disinfectant tolerance and antibiotic resistance mutations, preventing access to canonical evolutionary paths to resistance. Summary: Our findings suggest that phenotypic heterogeneity can facilitate disinfection survival and the evolution of population wide tolerance, which can impact future antibiotic resistance evolution. T2 - Vereinigung Allgemeiner und Angewandter Mikrobiobiologie Jahreskongress 2023 CY - Würzburg, Germany DA - 02.06.2024 KW - Biocide KW - Resistance KW - Persistence KW - Evolution KW - Herteogeneous phenotypes PY - 2024 AN - OPUS4-60244 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Nordholt, Niclas A1 - Schreiber, Frank T1 - Persistence against benzalkonium chloride promotes rapid evolution of tolerance under periodic disinfection N2 - Biocides used as disinfectants are important to prevent the transmission of pathogens, especially during the current antibiotic resistance crisis. This crisis is exacerbated by phenotypically tolerant persister subpopulations which can survive transient antibiotic treatment and facilitate resistance evolution. Despite the transient nature of disinfection, knowledge concerning persistence to disinfectants and its link to resistance evolution is currently lacking. Here, we show that E. coli displays persistence against a widely used disinfectant benzalkonium chloride (BAC). Periodic, persister-mediated failure of disinfection rapidly selects for BAC tolerance. BAC tolerance is associated with reduced cell surface charge and mutations in the novel tolerance locus lpxM. Moreover, the fitness cost incurred by BAC tolerance turned into a fitness benefit in the presence of antibiotics, suggesting a selective advantage of BAC-tolerant mutants in antibiotic environments. Our findings provide a mechanistic underpinning for the faithful application of disinfectants to prevent multi-drug-resistance evolution and to steward the efficacy of biocides and antibiotics. T2 - World Microbe Forum (ASM, FEMS) CY - Online meeting DA - 20.06.2021 KW - Persistence KW - Biocides KW - Evolution KW - Cross-resistance KW - Biocide tolerance PY - 2021 AN - OPUS4-53167 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Olbrich, Adelina-Elisa T1 - Material vs. Environment: Uncovering microbiological influenced corrosion processes on steel with single cell-ICP-ToF-MS N2 - Microbiologically influenced corrosion (MIC) is a highly unpredictable process dictated by the environment, microorganisms, and the respective electron source. Interaction pathways between cells and the metal surface remain unclear. The development of this novel single cell-inductively coupled plasma-time of flight-mass spectrometry analytical method and a MIC-specific staining procedure facilitate the investigation of steel-MIC interactions. With this it is possible to analyze the multi-elemental fingerprint of individual cells. The detection method revealed elemental selectivity for the corrosive methanogenic archaeal strain Methanobacterium-affiliated IM1. The interface between material and environmental analysis thus receives special attention, e.g., when considering MIC on solid steel. Hence, the possible uptake of individual elements from different steel samples is investigated. Results showed the cells responded at a single-cell level to the different types of supplemented elements and displayed the abilities to interact with chromium, vanadium, titanium, cobalt, and molybdenum from solid metal surfaces. The information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts, thus combining modern methods of analytical sciences with materials research. T2 - ToFcon 2022 CY - Online meeting DA - 17.11.2022 KW - Single cell KW - Microbiological influenced corrosion MIC KW - Sc-ICP-ToF-MS KW - Method development KW - Ir DNA staining approach KW - Carbon steel corrosion PY - 2022 AN - OPUS4-56355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Olbrich, Adelina-Elisa T1 - Deciphering microbiological influenced corrosion processes on steel with single cell-ICP-ToF-MS N2 - Microbiologically influenced corrosion (MIC) is a highly unpredictable process dictated by the environment, microorganisms, and the respective electron source. Interaction pathways between cells and the metal surface remain unclear. The development of this novel single cell-inductively coupled plasma-time of flight-mass spectrometry analytical method and a MIC-specific staining procedure facilitate the investigation of steel-MIC interactions. With this it is possible to analyze the multi-elemental fingerprint of individual cells. The detection method revealed elemental selectivity for the corrosive methanogenic archaeal strain Methanobacterium-affiliated IM1. The interface between material and environmental analysis thus receives special attention, e.g., when considering MIC on solid steel. Hence, the possible uptake of individual elements from different steel samples is investigated. Results showed the cells responded at a single-cell level to the different types of supplemented elements and displayed the abilities to interact with chromium, vanadium, titanium, cobalt, and molybdenum from solid metal surfaces. The information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts, thus combining modern methods of analytical sciences with materials research. References. T2 - Future WiNS CY - Berlin, Germany DA - 07.12.2022 KW - Single cell KW - Microbiological influenced corrosion MIC KW - Sc-ICP-ToF-MS KW - Method development KW - Ir DNA staining approach KW - Carbon steel corrosion PY - 2022 AN - OPUS4-56567 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Razkin Bartolomé, Malen T1 - Bacterial adhesion on fs-laser processed laser-induced periodic surface structures N2 - Bacteria are ubiquitous and colonize all types of surfaces, including those in close proximity to humans, such as skin, food, and everyday objects. This raises the question of whether their presence represents a problem to be mitigated or a potential source of benefit to be harnessed, thereby stimulating scientific inquiry into the role of surface-associated bacteria in diverse domains ranging fromhuman health to industrial biotechnology. Aim: The objective of this project is to explore the impact of modifying surface topography on bacterial adhesion behavior. By manipulating the physical characteristics of the substrate, the attachment and detachment dynamics of bacteria can potentially be modified, leading to novel strategies for controlling bacterial colonization in various applications, such as medical devices. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were tested on LIPSS-covered Fused Silica samples. T2 - 2023 Spring Meeting · , 2023 · Strasbourg CY - Strasbourg, France DA - 29.05.2023 KW - LIPSS KW - Biofilm KW - fs-laser processing PY - 2023 AN - OPUS4-58456 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Anja T1 - Bacterial adhesion on ultrashort laser processed surfaces N2 - Bacterial biofilms are multicellular communities adhering to surfaces and embedded in a self-produced extracellular matrix. Due to physiological adaptations and the protective biofilm matrix itself, biofilm cells show enhanced resistance towards antimicrobial treatment. In medical and industrial settings, biofilms on e.g. for implants or for surfaces in food-processing industry can be a fertile source of bacterial pathogens and are repeatedly associated with persisting, nosocomial and foodborne infections. As extensive usage of antibiotics and biocides can lead to the emergence of resistances, various strategies are currently developed, tested and improved to realize anti-bacterial surface properties through surface functionalization steps avoiding antibiotics. In this study, contact-less and aseptic large-area ultrashort laser scan processing is employed to generate different surface structures in the nanometer- to micrometer-scale on technical materials, i.e. titanium-alloy, steel, and polymer. The processed surfaces were characterized by optical and scanning electron microscopy and subjected to bacterial colonization studies with Escherichia coli test strains. For each material, biofilm results of the fs-laser treated surfaces are compared to that obtained on polished (non-irradiated) surfaces as a reference. Depending on the investigated surfaces, different bacterial adhesion patterns were found, suggesting an influence of geometrical size, shape and cell appendages of the bacteria and – above all – the laser-processed nanostructure of the surface itself. T2 - European Materials Research Society Spring Meeting 2021 CY - Online Meeting DA - 31.05.2021 KW - Bacterial adhesion KW - Biofilm formation KW - Ultrashort laser processing KW - Laser-induced periodic surface structures (LIPSS) PY - 2021 UR - https://www.european-mrs.com/laser-material-processing-fundamental-interactions-innovative-applications-emrs AN - OPUS4-52765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Anja T1 - Reducing Escherichia coli adhesion to PET by modulating spatial periods of laser-induced surface nanoripples N2 - Using nanofiber-like cell appendages, secreted proteins and sugars, bacteria can establish initial surface contact followed by irreversible adhesion and the formation of multicellular biofilms. Here, the stabilizing extracellular biofilm matrix together with physiological changes on the single cell level leads to an increased resilience towards harsh environmental conditions, antimicrobials, the host immune response and established cleaning procedures. Persistent microbial adhesion on e.g., medical implants, in water supply networks or food-processing industry is often associated with chronic inflammation, nosocomial and foodborne infections, enhanced biofouling and product contamination. To prevent persistent microbial colonization, antibacterial surface strategies often target the initial steps of biofilm formation and impede adhesion of single cells before a mature biofilm is being formed. While chemical coatings have been widely used, their restricted biocompatibility for eukaryotic cells and attenuated antibacterial-effects due to compound release limit their areas of application and alternative strategies focus on modified surfaces topographies to impede bacterial adhesion. In this work, we used ns-UV laser treatment (wavelength 248 nm and a pulse duration of 20 ns) to generate laser-induced periodic surface structures (LIPSS) with different submicrometric periods ranging from ~210 to ~610 nm on commercial poly(ethylene terephthalate) (PET) foils. Following structurally and chemically analyses, PET samples were subjected to bacterial colonization studies with Escherichia coli TG1, a bacterial test strain with a strong biofilm formation capacity due to the formation of nanofiber-like cell-appendages (pili). Bacterial adhesion tests revealed that E. coli repellence decisively depends on the spatial periods of the LIPSS with the strongest reduction (~91%) in cell adhesion observed for LIPSS periods of 214 nm. Scanning electron microscopy and additional biofilm studies using a pili-deficient E. coli TG1 strain revealed the importance of extracellular appendages in the bacterial repellence observed here, thus, pointing out new antibiotics-free strategies for antibacterial surfaces by impeding nanofiber-mediated bacterial adhesion. T2 - E-MRS Spring Meeting 2022 CY - Online meeting DA - 30.05.2022 KW - Laser-induced periodic surface structures (LIPSS) KW - Bacterial adhesion tests KW - Bacteria repellent surfaces KW - Polymer foils KW - E. coli PY - 2022 AN - OPUS4-54930 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Anja T1 - Laser-processing – a tool to direct biofilm formation N2 - Using nanofiber-like cell appendages, secreted proteins and sugars, bacteria can establish initial surface contact followed by irreversible adhesion and the formation of multicellular biofilms, often with enhanced resistance towards antimicrobial treatment and established cleaning procedures. On e.g. medical implants, in water supply networks or food-processing industry, biofilms can be a fertile source of bacterial pathogens and are repeatedly associated with persisting, nosocomial and foodborne infections. Nowadays, the emergence of resistances because of extensive usage of antibiotics and biocides in medicine, agriculture and private households have become one of the most important medical challenges with considerable economic consequences. In addition, aggravated biofilm eradication and prolonged cell-surface interaction can lead to increased biodeterioration and undesired modification of industrial and medical surface materials. Various strategies are currently developed, tested, and improved to realize anti-bacterial surface properties through surface functionalization steps avoiding antibiotics. In this study, contact-less and aseptic large-area short or ultrashort laser processing is employed to generate different surface structures in the nanometer- to micrometer-scale on technical materials such as titanium-alloy and polyethylene terephthalate (PET). The laser processed surfaces were subjected to bacterial colonization studies with Escherichia coli test strains and analyzed with reflected-light and epi-fluorescence microscopy. Depending on the investigated surfaces, different bacterial adhesion patterns were found, ranging from bacterial-repellent to bacterial-attractant effects. The results suggest an influence of size, shape and cell appendages of the bacteria and – above all – the laser-processed nanostructure of the surface itself, emphasizing the potential of laser-processing as a versatile tool to control bacterial surface adhesion. T2 - International Biodeterioration & Biodegradation Symposium 2021 CY - Online meeting DA - 06.09.2021 KW - Bacterial adhesion KW - Biofilm formation KW - Laser-induced periodic surface structueres (LIPPS) KW - Laser processing PY - 2021 UR - https://www.ibbs18.org/programme AN - OPUS4-53223 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Schmidt, Selina T1 - Effects of biocides on processes underlying resistance evolution N2 - Antimicrobial resistance (AMR) is a global health problem. It is well known that antibiotics can drive evolutionary processes that underlie antimicrobial resistance (AMR) evolution and spread in clinical and environmental settings. In contrast, less is known about the effects of antimicrobial substances that are used as biocides (i.e. disinfectants and preservatives) on AMR evolution and spread. Biocides are present in various settings, interacting with diverse microbial communities. Therefore, it is crucial to evaluate their role in the evolution and dissemination of antimicrobial resistance. Biocides occur in a wide range of concentrations in various environmental settings. By examining how the various concentrations affect selection mechanisms, we gain insights into potential developments related to antimicrobial resistance. The aim of this PhD thesis is to investigate the effects of biocides on processes underlying resistance evolution. Specifically, the work focused on key mechanisms for resistance spread, resistance evolution, and the effect of selection pressures on evolved resistance mechanisms. The thesis is structured around three major objectives: (i) to determine the effect of biocides on the evolution of resistance by affecting the rate of occurrence of de novo mutations, (ii) to determine the effect of biocides on the spread of resistance genes by modifying the rate of horizontal gene transfer (HGT) processes, and (iii) to investigate the selective drivers of the emergence of antimicrobial resistance in adaptive laboratory evolution (ALE) experiments. De-novo mutations are spontaneous mutations that occur at a certain rate in microorganisms. The effect of biocides at subinhibitory environmentally relevant concentrations on the mutation rate in Acinetobacer baylyi, Bacillus subtilis and Escherichia coli was assessed with the fluctuation assay. The results showed that biocides affected mutation rates in a species and substance dependent matter. The bisbiguanide chlorhexidine digluconate, the quaternary ammonium compound didecyldimethylammonium chloride, the metal copper, the pyrethroid-insecticide permethrin, and the azole-fungicide propiconazole increase mutation rates in E. coli, whereas no increases were identified for B. subtilis and A. baylyi. Horizontal gene transfer refers to diverse mechanisms that mediate the transfer of mobile genetic elements between microorganisms. This work focused on conjugation and transformation. Conjugation is a process whereby a conjugative plasmid is transferred from a donor cell to a recipient cell. Transformation is a process whereby exogenous donor DNA is taken up into a recipient cell and integrated into the recipient’s’ genome. The effects of subinhibitory environmentally relevant biocide concentrations on the conjugation rate of E. coli and the transformation rate of the naturally competent organisms A. baylyi in were assessed. The results showed that benzalkonium chloride (BAC), chlorhexidine and permethrin increased conjugation in E. coli, while none of the biocides increased transformation rates in A. baylyi. To further understand the molecular mechanisms underlying the effects on mutation and conjugation rates, I investigated the induction of the RpoS-mediated general stress and the RecA-linked SOS response upon biocide exposure. The results show a link between the general stress and the SOS response with increased rates of mutation and conjugation, but not for all biocides. One major approach to study the evolutionary response of bacteria to antimicrobials are ALE experiments with growth at subinhibitory concentrations linked to serial subculturing over many generations. Such experiments have been used to study resistance evolution to antibiotics and biocides. However, previous work showed that adaptation to biocide stress may be mediated by different evolutionary drivers. Here, I investigated the contributions of evolution for increased survival as opposed to improved growth in ALE experiments with E. coli exposed to subinhibitory BAC concentrations. Two distinct evolutionary treatments selecting for survival only or survival and growth led to specific evolutionary adaptations apparent in the phenotypes and genotypes of the evolved populations. Populations growing in the presence of BAC evolved increased fitness in the presence of BAC associated with higher resistance to BAC and cross-resistance to antibiotics, while this was not the case for populations evolving for increased survival only. Genotypic characterization by whole genome sequencing of the evolved populations revealed parallelism in mutated genes among replicate populations and distinct differences across treatments. Treatments selecting for survival and growth showed mutations in stress response related genes (hslO and tufA), while selection for survival led to mutations in genes for metabolic regulation (cyaA) and cellular structure (flagella fliJ). In summary, this thesis shows that biocides affect AMR evolution and emphasizes the importance of understanding of how biocides impact the molecular and evolutionary process that underlie AMR evolution. KW - Biocides KW - Antimicrobial resistances KW - Microbial survival mechanisms PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:188-refubium-43383-9 SP - 1 EP - 101 PB - Freie Universität CY - Berlin AN - OPUS4-60678 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Selina T1 - Antimicrobial resistance in soil microbes mediated by resistance evolution and horizontal gene transfer (HGT) N2 - Biocides are in contact with soils through direct application and passive leaching from protected materials. Consequently, soil microorganisms are exposed to biocides even though they are not their primary targets. Soil is a large reservoir of microbial diversity and has been hypothesized to be a crucial factor for the evolution and spread of antimicrobial resistance. Currently, there is little knowledge on how biocides used to protect materials affect the evolution and spread of resistance. Thus, our aim is to investigate the risk for the evolution of biocide resistance and cross-resistance to antibiotics. In addition, we aim to elucidate the affect of biocides on the spread of resistance via horizontal gene transfer (HGT). In adaptive laboratory evolution experiments we cultured selected model soil microorganism with representative biocides under selection regimes with increasing and stable biocide concentrations followed by antibiotic and biocide cross-resistance determination. Moreover, we investigate if the selected biocides affect the rates of de novo mutations and HGT of plasmids that carry resistance genes among soil microorganism. Our results show only small increases of biocide resistance during serial transfers under increasing biocide concentrations. One reason for this might be the narrow selective window for biocide resistance due to steep dose-response relationships. Furthermore, our results indicate that a stable low-level biocide regime did not select for high level cross-resistance to antibiotics and other biocides. Moreover, material preservatives affected the rates of HGT via conjugation and the mutation rates at sub-inhibitory concentrations. The results will enable future risk assessment regarding resistance evolution for biocides used as material preservatives. T2 - 4th Evo Eco PhD Meeting CY - Lutherstadt Wittenberg DA - 04.03.2020 KW - Microbiology KW - Biocides KW - Horizontal gene transfer HGT KW - Resistance evolution KW - Antimicrobial resistance PY - 2020 AN - OPUS4-51313 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Selina T1 - Biocides Used as Material Preservatives Modify Rates of de novo Mutation and Horizontal Gene Transfer in Bacteria N2 - Biocides used as material preservatives are in contact with various environments during direct application or passive leaching from protected materials. Antimicrobial resistance (AMR) is a global health problem and the environment is an important compartment for the evolution and transmission of AMR. Soil is an environment with a large reservoir of natural microbial communities and antimicrobial resistance (AMR) genes. Those natural microbial communities are frequently exposed to biocides used as material preservatives. Previous studies have shown that antibiotics, metals and pesticides affect the underlying processes of resistance evolution and spread; namely de novo mutagenesis and horizontal gene transfer by conjugation and transformation in microbial communities. However, it is unknown if active substances used in material preservatives are involved in these processes. We show that biocides used as material preservatives affect rates of mutation and conjugation in microorganism in a species- and substance-dependent manner, while rates of transformation are not directly affected. Our data highlights the importance of assessing the contribution of material preservatives on AMR evolution and spread in the environment. T2 - Microbiome Network Meeting CY - Berlin, Germany DA - 20.07.2022 KW - Biocides KW - Horizontal gene transfer KW - Mutation rate PY - 2022 AN - OPUS4-55263 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Selina T1 - Bacterial resistance evolution towards disinfectants and antimicrobial surfaces and development of a standardized test N2 - Question Disinfectants and antimicrobial surfaces (AMCs) are important tools to prevent the spread of pathogens and antimicrobial resistant bacteria. However, concerns have been raised about the possibility for the evolution and selection of resistance against disinfectants and AMCs. In turn, resistance against disinfectants and AMCs can be associated to antibiotic resistance due to cross-resistance - a single mechanism conferring resistance to a disinfectant and an antibiotic- and co-resistance - two distinct mechanisms physically linked on e.g. a plasmid. The risk for resistance and cross-resistance during use of biocides (including disinfectants and AMCs) must be evaluated during authorization according to the EU biocidal product regulation. However, to date there is a lack of standardized methods that support risk assessment during the authorization process. Methods We used adaptive laboratory evolution (ALE) experiments which are based on repeated exposure of bacteria to disinfectants or AMCs. The experiments are followed by phenotypic (antimicrobial susceptibility testing) and genotypic (whole genome sequencing) characterization of the evolved strains. The basic idea of these experiments is to expose bacteria to lethal conditions and select for mutants with increased survival. This approach is fundamentally different to other ALE experiments, which commonly select for increased growth at subinhibitory concentrations. However, selection for increased survival represents a selective pressure that more realistically reflects selection under in-use conditions of disinfectants and AMCs. Results First, we studied adaptation of E. coli during repeated disinfection with benzalkonium chloride in a suspension assay. The experiments showed a 2000-fold increase in survival within 5 exposure cycles. The adaptive changes are linked to highly parallel mutations in genes related to lipid A biosynthesis, less negative cell surface charge, reduced growth rate and increased competitive ability in the presence of certain antibiotics. We use the same approach to develop standardizable ALE experiments based upon accepted standards that are used to determine the efficacy of disinfectants (EN 13697) and antimicrobial surfaces (ISO 22196). The results highlight pronounced adaptation of different test strains towards surface disinfection (benzalkonium chloride and isopropanol) and AMCs (copper). Conclusion Bacteria can adapt with increased survival towards lethal stress imposed by disinfectants and AMCs. The adaptive ability of bacteria to disinfectants and AMCs can be determined in a standardized manner. T2 - 74. Jahrestagung der Deutschen Gesellschaft für Hygiene und Mikrobiologie [DGHM] e. V. CY - Berlin, Germany DA - 05.09.2022 KW - Antimicrobial surfaces KW - ISO22196 KW - Antimicrobial resistance KW - Round robin test PY - 2022 AN - OPUS4-56432 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Selina T1 - Biocides Used as Material Preservatives Modify Rates of De Novo Mutation And Horizontal Gene Transfer in Bacteria N2 - Antimicrobial resistance (AMR) is an important global health problem. The environment has been regocnized as an improtant compartment for the occurance, evolution and transmission of AMR. Biocides used as material preservatives are in contact with the environment and natural microbial communities through direct application and passive leaching from protected materials. It has been shown that environmental contaminants, such as antibiotics, metals and pesticides, can affect resistance evolution and spread by modifying the underlying processes of de novo mutagenesis, horizontal gene transfer and selection. However, it is unknown if material preservatives are involved in these processes and thereby can also drive AMR in the environment. Here, we investigate the effect of material preservatives on rates of de novo mutation and horizontal gene transfer (HGT) in Escherichia coli and the model soil microorganisms Acinetobacter baylyi and Bacillus subtilis. To this end, we determined the effects of material preservatives on the mutation rates and HGT with the Luria-Delbrück fluctuation assay and a conjugation assay with the broad host-range plasmid pKJK5 and a transformation assay. Our data shows that the quaternary ammonium compound DDAC, copper, the pyrethroid insecticide permethrin and the azole fungicide propiconazole significantly increase mutation rates in E. coli, whereas A. baylyi and B. subtilis are not significantly affected. Moreover, we show that the carbamate IPBC and the insecticide permethrin affect HGT in a concentration dependent manner. Investigations with reporter strains for bacterial stress response pathways show that induction of the general stress response (rpoS) and components of the SOS response (recA) underlie the effects of most biocides on mutation rates and HGT. Taken together, our data is important for assessing the contribution of biocides on AMR evolution and spread in the environment. T2 - World Microbe Forum (ASM, FEMS) CY - Online meeting DA - 20.06.2021 KW - Biocides KW - Horizontal gene transfer KW - Mutation rate PY - 2021 UR - https://www.abstractsonline.com/pp8/#!/9286/presentation/11692 AN - OPUS4-54211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Selina T1 - Effect of biocides on the evolution and spread of resistance N2 - Biocides used as material preservatives are in contact with various environments during direct application or passive leaching from protected materials. Antimicrobial resistance (AMR) is a global health problem and the environment is an important compartment for the evolution and transmission of AMR. Soil is an environment with a large reservoir of natural microbial communities and antimicrobial resistance (AMR) genes. Those natural microbial communities are frequently exposed to biocides used as material preservatives. Previous studies have shown that antibiotics, metals and pesticides affect the underlying processes of resistance evolution and spread; namely de novo mutagenesis and horizontal gene transfer by conjugation and transformation in microbial communities. However, it is unknown if active substances used in material preservatives are involved in these processes. We show that biocides used as material preservatives affect rates of mutation and conjugation in microorganism in a species- and substance-dependent manner, while rates of transformation are not directly affected. Our data highlights the importance of assessing the contribution of material preservatives on AMR evolution and spread in the environment. T2 - Microbiome Network Meeting CY - Berlin, Germany DA - 20.07.2022 KW - Biocides KW - Antimicrobial resistance KW - Horizontal gene transfer KW - Mutation rate PY - 2022 AN - OPUS4-56426 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Selina T1 - Effect of biocides on the evolution and spread of resistance N2 - Biocides used as material preservatives are in contact with various environments during direct application or passive leaching from protected materials [1]. Antimicrobial resistance (AMR) is a global health problem and the environment is an important compartment for the evolution and transmission of AMR [2,3]. Soil is an environment with a large reservoir of natural microbial communities and antimicrobial resistance (AMR) genes. Those natural microbial communities are frequently exposed to biocides used as material preservatives. Previous studies have shown that antibiotics, metals and pesticides affect the underlying processes of resistance evolution and spread; namely de novo mutagenesis and horizontal gene transfer by conjugation and transformation in microbial communities. However, it is unknown if active substances used in material preservatives are involved in these processes. We show that biocides used as material preservatives affect rates of mutation and conjugation in microorganism in a species- and substance-dependent manner, while rates of transformation are not directly affected. Our data highlights the importance of assessing the contribution of material preservatives on AMR evolution and spread in the environment. T2 - RokoCon2022 CY - Berlin, Germany DA - 29.09.2022 KW - Biocide KW - Antimicrobial resistance KW - Tolerance KW - Horizontal gene transfer KW - Mutation rate PY - 2022 AN - OPUS4-56431 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schreiber, Frank T1 - Biocide Resistance - Road to Risk Assessment N2 - This presentation details the current status of biocide resistance risk assessment and provides a roadmap for future activities. T2 - OECD, 6th Meeting of the Working Party on Biocides CY - Paris, France DA - 28.09.2022 KW - Antimicrobial resistance KW - Antimicrobial coating KW - Standardization KW - Biocides KW - Risk assessment PY - 2022 AN - OPUS4-56263 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schreiber, Frank T1 - Die Entstehung von antimikrobiellen Resistenzen durch die Verwendung von Bioziden N2 - Dieser Vortrag gibt einen Überblick über die BAM und die Aktivitäten im Bereich Biozidresistenz. T2 - Berliner Hochschule für Technik Studiengang Biotechnologie CY - Berlin, Germany DA - 05.05.2023 KW - Antimikrobielle Resistenz KW - Antmikrobielle Oberflächen KW - Standardisierung PY - 2023 AN - OPUS4-57859 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schreiber, Frank T1 - How to regulate and assess resistance risks of co-selecting agents during application and in the environment N2 - This talk deals with the question on How to regulate and assess resistance risks of co-selecting agents during application and in the environment. It shows that there the overview of worldwide activities to regulate co-selecting agents is missing. Regulations for product authorization usually consider resistance in target organisms, but there is a risk of emergence of resistance from non-target organisms as well. Moreover, pollution effects on resistance development in the environment are not explicitly covered during product authorization and few risk assessment schemes and methods available. T2 - EDAR7 - Environmental Dimension of Antimicrobial Resistance Conference 2024 CY - Montreal, Canada DA - 26.05.2024 KW - Antimicrobial resistance KW - Bacteria KW - Standardization KW - Biocides PY - 2024 AN - OPUS4-61542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schreiber, Frank T1 - Development of a laboratory method to assess resistance development of microorganisms to biocides – An update N2 - This presentation describes the development of a laboratory method to assess resistance development of microorganisms to biocides and antimicrobial surfaces. T2 - The International Biodeterioration Research Group (IBRG) autumn meeting 2022 CY - Online meeting DA - 11.10.2022 KW - Antimicrobial resistance KW - Antimicrobial coating KW - Standardization KW - Biocides KW - Risk assessment PY - 2022 AN - OPUS4-56264 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schreiber, Frank T1 - Development of a laboratory method to assess resistance development of microorganisms to biocides – An update N2 - This presentation describes our efforts at BAM towards the development of a laboratory method to assess resistance development of microorganisms to biocides. T2 - The International Biodeterioration Research Group (IBRG) spring meeting 2023 CY - Online meeting DA - 05.03.2023 KW - Antimicrobial resistance KW - Antimicrobial coating KW - Standardization KW - Biocides PY - 2023 AN - OPUS4-57858 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schreiber, Frank T1 - Development of a laboratory method to assess resistance development of microorganisms to biocides N2 - Bacteria are exposed to biocides through surface disinfection or by antimicrobial surfaces. These stressful environments provide a strong selective pressure for bacteria to adapt. Here, we describe the development of a laboratory method to assess adaption of bacteria by resistance development in response to surface disinfection and antimicrobial surfaces. T2 - OECD, 5th Meeting of the Working Party on Biocides CY - Online meeting DA - 26.05.2021 KW - Antimicrobial resistance KW - Antimicrobial coating KW - Standardization PY - 2021 AN - OPUS4-53163 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schreiber, Frank T1 - Development of a laboratory method to assess resistance development of microorganisms to biocides N2 - Bacteria are exposed to biocides through surface disinfection or by antimicrobial surfaces. These stressful environments provide a strong selective pressure for bacteria to adapt. Here, we describe the development of a laboratory method to assess adaption of bacteria by resistance development in response to surface disinfection and antimicrobial surfaces. T2 - The International Biodeterioration Research Group (IBRG) Spring Meeting 2021 CY - Online meeting DA - 28.06.2021 KW - Antimicrobial resistance KW - Antimicrobial coating KW - Standardization PY - 2021 AN - OPUS4-53164 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -