4 Material und Umwelt
Filtern
Dokumenttyp
- Zeitschriftenartikel (84)
- Vortrag (73)
- Posterpräsentation (62)
- Beitrag zu einem Tagungsband (9)
- Dissertation (3)
- Buchkapitel (2)
- Sonstiges (2)
- Forschungsbericht (2)
- Beitrag zu einem Sammelband (1)
- Video (1)
Sprache
- Englisch (239) (entfernen)
Schlagworte
- Biocides (45)
- Antimicrobial resistance (34)
- Bacteria (22)
- Biofilms (22)
- Corrosion (20)
- MIC (18)
- Evolution (13)
- Methanogens (13)
- Microbiologically influenced corrosion (13)
- Biofilm (12)
- Disinfection (11)
- E. coli (11)
- NAP-XPS (11)
- Antimicrobial coating (10)
- Biocide (9)
- Persistence (9)
- Resistance (9)
- Archaea (8)
- Ectoine (8)
- Microbiology (8)
- Standardization (8)
- Horizontal gene transfer HGT (7)
- Laser-induced periodic surface structures (LIPSS) (7)
- Resistance evolution (7)
- Antibiotics (6)
- Bacterial adhesion (6)
- Biocide tolerance (6)
- Horizontal gene transfer (6)
- Termites (6)
- Tolerance (6)
- Wood protection (6)
- Alginate (5)
- Cross-resistance (5)
- Environmental Simulation (5)
- Heterogeneity (5)
- Korrosion (5)
- Methanogen (5)
- Mutation rate (5)
- Risk assessment (5)
- Sc-ICP-ToF-MS (5)
- Single cell analysis (5)
- XPS (5)
- Anobium punctatum (4)
- Antimicrobials (4)
- Biocorrosion (4)
- Biofilm formation (4)
- Carbon steel (4)
- Corrosion products (4)
- Glutaraldehyde (4)
- Method development (4)
- NanoSIMS (4)
- Polyethylene (4)
- Tineola bisselliella (4)
- Antimicrobial (3)
- Antimicrobial surfaces (3)
- Carbon steel corrosion (3)
- Environmental simulation (3)
- FIB/SEM (3)
- Flow Model (3)
- Halomonas elongata (3)
- Immunity (3)
- Ir DNA staining approach (3)
- LIPSS (3)
- Laser processing (3)
- Metabolism (3)
- Methanogen-induced microbiologically influenced corrosion (3)
- Microbiological influenced corrosion MIC (3)
- Modelling (3)
- Modelling studies (3)
- Nanoparticles (3)
- Osmoadaptation (3)
- Phenotypic diversity (3)
- SC-ICP-ToF-MS (3)
- Single cell (3)
- Sulfate reducing bacteria (3)
- Termite (3)
- Wastewater (3)
- Wood Protection (3)
- Anoxia (2)
- Antagonism (2)
- Antibiotic resisitance (2)
- Apanteles carpatus (2)
- Bacterial adhesion tests (2)
- Bacterial attachment (2)
- Baryscapus tineivorus (2)
- Biodiversity (2)
- Biofilm growth (2)
- Bioinformatics (2)
- Biological pest control (2)
- Biotechnology (2)
- Brown-rot fungi (2)
- Compatible solute (2)
- Condensed Matter Physics (2)
- Corynetes caeruleus (2)
- Cultural heritage (2)
- DNA (2)
- Degradation (2)
- Desinfectant (2)
- Disinfectants (2)
- E.coli (2)
- Energy Engineering and Power Technology (2)
- Environmental condition (2)
- Flow system (2)
- Fuel Technology (2)
- HAXPES (2)
- Halomonas CRISPR Ectoine (2)
- Halophile (2)
- Hi-Tension (2)
- Insect biotechnology (2)
- Iron (2)
- Isoptera (2)
- Keratin (2)
- Korynetes caeruleus (2)
- Leaching (2)
- Life history data (2)
- Microbiologically influenced corrosion (MIC) (2)
- Microorganism (2)
- Mikrobiell beeinflusste Korrosion (2)
- Model (2)
- Nitrogen (2)
- Nosema ceranae (2)
- Optics (2)
- Osmia bicornis (2)
- Persister cells (2)
- Pollutants (2)
- Pseudomonas aeruginosa (2)
- Reactive oxygen species (2)
- Renewable Energy, Sustainability and the Environment (2)
- Risk assesment (2)
- Shale (2)
- Social (2)
- UV-irradiation (2)
- Wild bees (2)
- 2D nanomaterials (1)
- 3D printing (1)
- A-DNA conformation (1)
- AMR (1)
- Academia (1)
- Acidobacteria (1)
- Agarose (1)
- Alkylating agents (1)
- Amphiphilic polymer (1)
- Anaerobic pathways (1)
- Analytical standards (1)
- Anti-microbial effects (1)
- Antiadhesive surfaces (1)
- Antibacterial (1)
- Antibacterial polymer (1)
- Antibacterial surfaces (1)
- Antibiotic (1)
- Antibiotic resistance (1)
- Antifouling (1)
- Antimicrobial Resistance (1)
- Antimicrobial resistances (1)
- Antimicrobial test (1)
- Antiseptic agents (1)
- Artificial weathering (1)
- Aspergillus (1)
- Aspergillus flavus (1)
- Atomic and Molecular Physics and Optics (1)
- Atomic force microscopy (1)
- Automated analysis (1)
- BODIPY (1)
- Bacillus subtilis (1)
- Bacteria repellent surfaces (1)
- Bacteria-repellent surfaces (1)
- Bacterial cell cycle (1)
- Bacterial growth (1)
- Bacterial second messenger (1)
- Bankia sp (1)
- Basidiomycetes (1)
- Bee diseases (1)
- Bee health (1)
- Beneficial microbes (1)
- Biodeterioration (1)
- Biodeterioration and biodegradation (1)
- Biofilm quantification (1)
- Biofouling (1)
- Bioilm (1)
- Bioinformatics virology viruses software (1)
- Biokorrosion (1)
- Biological Control (1)
- Biological control (1)
- Biomimetic (1)
- Biosynthesis (1)
- Biphasic growth (1)
- C-di-GMP (1)
- COST Action (1)
- COST action CA15114 AMICI (1)
- CRISPR dCas9 (1)
- Calcareous deposits (1)
- Cast iron (1)
- Cathodic protection (1)
- Cell appendages (1)
- Cell studies (1)
- Cell-envelope (1)
- Cellulose synthase (1)
- Chemicals (1)
- Cleridae (1)
- Coleoptera (1)
- Conditioning layer (1)
- Coniophora puteana (1)
- Conjugate (1)
- Conjugation (1)
- Contamination (1)
- Controlled atmosphere (1)
- Coptotermes (1)
- Core microbiome (1)
- Corrosion product (1)
- Cribellate spiders (1)
- Cross-feeding (1)
- Cryo XPS (1)
- CuNPs (1)
- Cultural Heritage (1)
- Cupriavidus campinensis (1)
- DNA barcode (1)
- DSM 5009 (1)
- Decomposition point (1)
- Degradable polymer (1)
- Denitrification (1)
- Desert ecology (1)
- Deterioration (1)
- Dielectric heating (1)
- Dietary adaptation (1)
- Diffractive gratings (1)
- Direct laser writing (1)
- Disinfection Fuel (1)
- Disposal (1)
- Diversity (1)
- Drywood termite (1)
- Durability (1)
- Dye (1)
- E$volution (1)
- Ecology (1)
- Efficacy (1)
- Efflux (1)
- Electronic (1)
- Environment (1)
- Environmental conditions (1)
- Environmental simulations (1)
- Essential oils (1)
- Exocrine gland (1)
- Experimental evolution (1)
- External (1)
- Extremophile (1)
- F pili (1)
- Femtosecond laser processing (1)
- Fenton-like reaction (1)
- Flow chamber system (1)
- Flow-System (1)
- Flow-system (1)
- Fluorescence (1)
- Fluorescence spectroscopy (1)
- Fluoride (1)
- Fluoride nanoparticles (1)
- Fluorides (1)
- Fluorolytic sol-gel synthesis (1)
- Fluorolytic sol−gel (1)
- Food fermentation (1)
- Food safety (1)
- Force distance curve (1)
- Fuel sorption (1)
- Functionalized graphene (1)
- Fungal decay (1)
- Fungi (1)
- Fungicidal property (1)
- Fungiculture (1)
- Fungus (1)
- Fusarium (1)
- Gas storage (1)
- Gene expression (1)
- Genome sequence (1)
- Geological formation (1)
- Geology (1)
- Graphene (1)
- Graphene–bacteria interaction (1)
- Growth-rate homeostasis (1)
- Gut symbionts (1)
- HI-Tension (1)
- Halogenation (1)
- Halophilic (1)
- Halophilic bacteria (1)
- Healthcare (1)
- Herteogeneous phenotypes (1)
- High density polyethylene (1)
- High salinity (1)
- Holzschutzmittel (1)
- Hospital premises (1)
- Hydrogen (1)
- Hydrogen permeation (1)
- Hydrogen storage (1)
- Hydrogenasen (1)
- Hydrophobic interaction (1)
- Hylotrupes bajulus (1)
- Hylotrupes bajulus, Anobium punctatum, natural durability, tropical wood, native wood. (1)
- Hyperarid (1)
- Hypopharynx (1)
- IPM in museums (1)
- IR spectroscopy (1)
- ISO22196 (1)
- Implants (1)
- In situ (1)
- Industrial applications (1)
- Infections (1)
- Initial attachment (1)
- Insect evolution (1)
- Insecticide (1)
- Interdisciplinarity (1)
- Interdisciplinary (1)
- Iodine (1)
- Ionic liquid (1)
- Ionizing radiation (1)
- Issues (1)
- Laboratory breeding (1)
- Labrum (1)
- Lake Cadagno (1)
- Laser structuring (1)
- Laser-induced nanostructures (1)
- Laser-induced pariodic surface structures (1)
- Laser-induced periodic surface structueres (LIPPS) (1)
- Laser-modified surface (1)
- Library pests (1)
- Lifetime (1)
- Lightning talk (1)
- Limnoria spp (1)
- Low alloy steel (1)
- MDG ICP-ToF-MS (1)
- MIC Island (1)
- MIC projekt (1)
- Marek's virus (1)
- Marine borers (1)
- Material degradation (1)
- Materials (1)
- Mechanosensitive channel (1)
- Melting point (1)
- Melting temperature (1)
- Metabolic engineering (1)
- Metabolic flux analysis (1)
- Metabolic modeling (1)
- Metabolomics (1)
- Metal organic frameworks (1)
- Metal reducing bacteria (1)
- Metalls (1)
- Methane (1)
- Methanogenesis (1)
- Microbial (1)
- Microbial adhesions (1)
- Microbial community modelling (1)
- Microbial simulation, (1)
- Microbial survival mechanisms (1)
- Microbially Induced Corrosion (1)
- Microbiologically Influrenced Corrosion (MIC) (1)
- Microdroplet generator (1)
- Microfluidics (1)
- Micromonospora aurantiaca (1)
- Micropatterning (1)
- Microwaves (1)
- Migration (1)
- Mircobially influcenced corrosion (1)
- Modeling (1)
- Modified mycotoxins (1)
- Moisture (1)
- Moisture performance (1)
- Molecular (1)
- Molecular clock (1)
- MscS (1)
- Mud volcanoe fluids (1)
- Multi-resistant bacteria (1)
- Multiple lines of evidence (1)
- Multiport (1)
- Museum Pests (1)
- Museum insect pest (1)
- Museum pests (1)
- Mussel-inspired coating (1)
- Mussel-inspired materials (1)
- Mycotoxin (1)
- Mycotoxins (1)
- Nano Particles (1)
- Nano characterization (1)
- Nano metal fluorides (1)
- Nanobiocide (1)
- Nanocoating (1)
- Nanorods (1)
- Natural durability (1)
- Natural products discovery (1)
- Near ambient pressure XPS (1)
- Near ambient x-ray photoelectron spectroscopy (1)
- Next generation sequencing (1)
- Nitrous oxide (1)
- Nonvolatile (1)
- Nuclear waste disposal (1)
- Oil and gas industry (1)
- Oil and gas reservoir (1)
- Oilfield (1)
- One-step ionic liquids synthesis (1)
- Optical and Magnetic Materials (1)
- Osmophobic effect (1)
- Osmotic shock (1)
- Osteogenesis (1)
- P. Fluorescens (1)
- PE-HD (1)
- Paper sizings (1)
- Particle synthesis (1)
- Pathogen spillover (1)
- Pathogen transmission (1)
- Performance (1)
- Permeability (1)
- Persian historical recipes (1)
- Persian manuscripts (1)
- Pest control (1)
- Phenotypic heterogeneity (1)
- Phenotypic variation (1)
- Photodynamic therapy (1)
- Photonics (1)
- Physical and optical characteristics (1)
- Plastic degradation (1)
- Polydopamine (1)
- Polyethylene terephthalate (1)
- Polyglycerol (1)
- Polyioinic liquid (1)
- Polymer foils (1)
- Polymer-based products (1)
- Poster presentation (1)
- Preferential binding (1)
- Preferential exclusion (1)
- Proteome (1)
- Pseudomonas (1)
- Pseudomonas fluorescens (1)
- Pseudomonas veronii (1)
- Ptinidae (1)
- Quasispecies (1)
- RNA-Sequencing (1)
- Radio waves (1)
- Reactor conditions (1)
- Resistance model (1)
- Rhizopus (1)
- Rhizopus and Aspergillus oryzae (1)
- Rhodonia placenta (1)
- Round robin test (1)
- Ruthenium (1)
- SEM (1)
- SEM micrography (1)
- SEM wood characterization (1)
- SEM-EDS (1)
- SIMS (1)
- SRB (1)
- Selection (1)
- Self-assembled monolayer (1)
- Sensors (1)
- Silica and polystyrene nanoparticles (1)
- Silver (1)
- Single cell microbiology (1)
- Sizing (1)
- Social immunity (1)
- Social insects (1)
- Software (1)
- Soil contact (1)
- Soldier (1)
- Solitary bees (1)
- Solubility (1)
- Solute excretion (1)
- Spectral imaging (1)
- Stainless steel (1)
- Stakeholder (1)
- Standardisation (1)
- Standardized test and quantification procedure (1)
- Structural color (1)
- Superhydrophilic surface (1)
- Superhydrophobic surface (1)
- Suppression (1)
- Surface functionalization (1)
- Survival rates (1)
- Symbiosis (1)
- Synchrotron-XPS (1)
- Synergy (1)
- Synthetic metabolism (1)
- Teredo sp (1)
- Termite control (1)
- Termite-associated microbes (1)
- Termitoidae (1)
- Thermodynamic (1)
- Thioimidazolium (1)
- ToF SIMS (1)
- ToF-SIMS (1)
- Touch surfaces (1)
- Trait-based ecology (1)
- Transcriptomics (1)
- Ultrashort laser processing (1)
- Ultrastructure (1)
- Velocimetry (1)
- Virology (1)
- Virulence (1)
- Viruses (1)
- Water (1)
- Water atmosphere (1)
- Water stable isotope analysis (1)
- Water uptake (1)
- White-rot fungi (1)
- Wood Modification (1)
- X-ray spectroscopic techniques (1)
- X-ray tomographic (1)
- XANES (1)
- Xestobium rufovillosum (1)
- Zearalenone (1)
- Zearalenone sulfate (1)
- a-zearalenol (1)
- biocide tolerance (1)
- disinfection (1)
- dsDAN monolayer (1)
- evolution (1)
- fs-laser processing (1)
- heterogeneity (1)
- iChip (1)
- pH probe (1)
- underexplored phyla (1)
Organisationseinheit der BAM
- 4.1 Biologische Materialschädigung und Referenzorganismen (239) (entfernen)
Paper des Monats
- ja (6)
Eingeladener Vortrag
- nein (73)
Question:
Biocides are in contact with soils through direct application and passive leaching from protected materials. Consequently, soil microorganisms are exposed to toxic 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).
Methods:
In laboratory evolution experiments we culture selected model soil microorganism with representative biocides followed by antibiotic cross-resistance determination and genome sequencing. Moreover, we investigate if the selected biocides affect the HGT frequency of plasmids that carry resistance genes among soil microorganism and the consequences for survival of the affected populations.
Results:
Our initial results show only small increases of biocide resistance during serial transfers in the presence of biocides. One reason for this might be the narrow selective window for biocide resistance due to steep dose-response relationships. Furthermore, we will present results from ongoing experiments on the effects of material preservatives on HGT frequencies facilitating microbial community adaptation to stress.
Conclusions:
The results will enable future risk assessment regarding resistance evolution for biocides used as material preservatives.
Microbiologically influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) in offshore industries, such as the oil and gas pipelines, due to the high concentrations of sulfate in the seawater. SRM act upon the metal by the reactiveness of hydrogen sulfide (HS-), and by withdrawal of the available electrons (Fe --> Fe2+ + 2e-; E° = -0.47 V) in electrical contact with the metal (EMIC). However, methanogenic archaea can also cause MIC. Because they do not produce HS-, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood.
To investigate the corrosion potential of methanogens, we studied the EMIC methanogenic strains isolated from marine sediments (Methanobacterium-affiliated strain IM1) and crude oil tanks (Methanococcus maripaludis Mic1c10), in an in-house developed flow-through cell to simulate a fluctuating environment. A co-culture of M. maripaludis and D. alaskensis was also established to study the effect of syntrophic growth on metal corrosion that may occur in industrial pipelines. Results indicate that the rates of iron corrosion due to coupled methanogenesis (up to 0.4 mm/yr) are higher to that caused by the marine SRM Desulfovibrio alaskensis (0.15 mm/yr). Surface analyses of the metal showed severe pitting with high methane production. Genomic analysis of the EMIC methanogen M. maripaludis Mic1c10 will provide an insight on the mechanisms of MIC. Such knowledge and deeper understanding also from an electrokinetic point of view may not only provide further models in microbial electrophysiology, but also contribute to mitigation strategies in MIC
Question:
Biocides are in contact with soils through direct application and passive leaching from protected materials. Consequently, soil microorganisms are exposed to toxic 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).
Methods:
In laboratory evolution experiments we culture selected model soil microorganism with representative biocides followed by antibiotic cross-resistance determination and genome sequencing. Moreover, we investigate if the selected biocides affect the HGT frequency of plasmids that carry resistance genes among soil microorganism and the consequences for survival of the affected populations.
Results:
Our initial results show only small increases of biocide resistance during serial transfers in the presence of biocides. One reason for this might be the narrow selective window for biocide resistance due to steep dose-response relationships. Furthermore, we will present results from ongoing experiments on the effects of material preservatives on HGT frequencies facilitating microbial community adaptation to stress.
Conclusions:
The results will enable future risk assessment regarding resistance evolution for biocides used as material preservatives.
Questions:
Biocides are in contact with soils through direct application and passive leaching from protected materials. Consequently, soil microorganisms are exposed to toxic 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).
Methods:
In laboratory evolution experiments we culture selected model soil microorganism with representative biocides followed by antibiotic cross-resistance determination and genome sequencing. Moreover, we investigate if the selected biocides affect the HGT frequency of plasmids that carry resistance genes among soil microorganism and the consequences for survival of the affected populations.
Results:
Our initial results show only small increases of biocide resistance during serial transfers in the presence of biocides. One reason for this might be the narrow selective window for biocide resistance due to steep dose-response relationships. Furthermore, we will present results from ongoing experiments on the effects of material preservatives on HGT frequencies facilitating microbial community adaptation to stress.
Conclusions:
The results will enable future risk assessment regarding resistance evolution for biocides used as material preservatives.
The container of high-level radioactive waste (HLRW) being in deep geological disposal, the backfill material is needed to serve as the second defense for HLRW and the highly compacted bentonite is generally selected. As the time goes, the underground water will infiltrate the backfill, causing the corrosion of materials for the building of containers in the formed electrolyte. Carbon steel, titanium and its alloy are the potential candidate materials for the fabrication of HLRW containers.
The current investigation aims at assessing the safety of HLRW container in deep geological disposal for hundreds of thousands of years and facilitating the material selection for future Container fabrication by estimating their corrosion behavior in compacted bentonite with a series of moisture content at different temperatures through electrochemical methods including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PC) measurements. The corrosion rates were estimated for a carbon steel, a pure titanium and a titanium alloy in compacted Gaomiaozi Bentonite infiltrated with simulated underground water in Beishan area of China over an expected disposal period up to 106 years respectively, showing that titanium and its alloy are more reliable materials for building HLRW containers than carbon steel.
An understanding of the interactions of 2D nanomaterials with pathogens is of vital importance to developing and controlling their antimicrobial properties. In this work, the interaction of functionalized graphene with tunable hydrophobicity and bacteria is investigated. Poly-(ethylene glycol)-block-(poly-N-isopropylacrylamide) copolymer (PEG-b-PNIPAM) with the triazine joint point was attached to the graphene Surface by a nitrene [2 + 1] cycloaddition reaction. By thermally switching between hydrophobic and hydrophilic states, functionalized graphene sheets were able to bind to bacteria. Bacteria were eventually disrupted when the functionality was switched to the hydrophobic state. On the basis of measuring the different microscopy methods and a live/dead viability assay, it was found that Escherichia coli (E. coli) bacteria are more susceptible to hydrophobic interactions than B. cereus bacteria, under the same conditions. Our investigations confirm that hydrophobic interaction is one of the main driving forces at the presented graphene/bacteria interfaces and promotes the antibacterial activity of graphene derivatives significantly.
In this study, femtosecond laser-induced sub-micrometer structures are generated to modify polyethylene (PE) surface topographies. These surfaces were subjected to bacterial colonization studies with Escherichia coli and Staphylococcus aureus as test strains. The results reveal that the nanostructures do not influence S. aureus coverage, while the adhesion of E. coli is reduced.
Bacterial samples are typically freeze dried or cryo-prepared prior to XPS analysis to allow for measurements in ultra-high vacuum (UHV). The sample environment in the near-ambient pressure (NAP) XPS instrument EnviroESCA allows for measurements in up to 15 mbar water vapor, thus, sample preparation is no longer restricted to UHV-compatible techniques. For instance, biofilms grown in medium can be transferred directly from the medium to the measurements chamber, maintaining a humid environment throughout the measurements. Considering the complexity of bacterial samples, sample preparation must be carefully considered in order to obtain meaningful and reproducible results.
In this talk, various strategies for sample preparation of bacteria and biofilms for NAP-XPS measurements will be discussed. Model systems of planktonic bacteria, artificial biofilms resembling the exopolysaccharide matrix and biofilms have been characterised in various conditions. The stability and homogeneity of the samples was assessed by monitoring the C1s core level peak at different sample locations. The quality of the XPS-spectra is also influenced by the gas environment, which will be exemplified by core level spectra of P. Fluorescens acquired in air, water vapor and ultra-high vacuum.
Introduction: Biofilms are regarded as a common cause of chronic infections on medical devices. Preventive and therapeutic strategies against biofilm infections commonly involve applications of multiple antimicrobial substances: antimicrobial coatings on the implanted biomaterials in combination with systemically administered antibiotics. While this practice of combination therapy harbours the risk of developing cross-resistance, it might also provide the possibility to implement specific antimicrobial-antibiotic combinations (AACs) that can slow down the selection of antibiotic resistant strains.
Hypothesis and aims: Specific AACs can exert combinatorial effects on the growth of susceptible and antibiotic-resistant Pseudomonas aeruginosa that either suppress or increase their individual effects.
Our aim is to identify AACs with antagonistic or synergistic effects on pseudomonal biofilms and to understand their impact on selection of resistant strains. Specifically, we want to identify AACs that select for and against antibiotic resistance during biofilm formation.
Methodology: We screened for AACs that cause antagonistic or synergistic effects on planktonic P. aeruginosa.
To study the effect of antimicrobial-antibiotic exposure on resistance selection in bacterial biofilms, we will grow resistant and sensitive strains on PDMS surfaces with and without antimicrobial coatings and expose them to antibiotics.
Results: Several combinations with synergistic or antagonistic interaction on the growth rate of P. aeruginosa were detected. We observed a strong antagonism when combining the antimicrobial substance chlorhexidine with the carbapenem drug meropenem. A meropenem-resistant mutant showed a selection advantage in low concentrations of chlorhexidine combined with a sub-inhibitory concentration of meropenem over the wild-type. No antagonistic effect was observed for the same combination when E. coli was exposed to chlorhexidine and meropenem, suggesting a non-chemical basis for the observed effect on P. aeruginosa.
Conclusion: Gaining a better understanding about resistance selection during biofilm formation on biomedical surfaces will enable us to mitigate against biofilm-associated antimicrobial resistance.
Tempeh is a common food in Indonesia, produced by fungal fermentation of soybeans using Rhizopus sp., as well as Aspergillus oryzae, for inoculation. Analogously, for economic reasons, mixtures of maize and soybeans are used for the production of so-called tempeh-like products. For maize, a contamination with the mycoestrogen zearalenone (ZEN) has been frequently reported. ZEN is a mycotoxin which is known to be metabolized by Rhizopus and Aspergillus species. Consequently, this study focused on the ZEN transformation during tempeh fermentation. Five fungal strains of the genera Rhizopus and Aspergillus, isolated from fresh Indonesian tempeh and authentic Indonesian inocula, were utilized for tempeh manufacturing from a maize/soybean mixture (30:70) at laboratory-scale. Furthermore, comparable tempeh-like products obtained from Indonesian markets were analyzed. Results from the HPLC-MS/MS analyses show that ZEN is intensely transformed into its metabolites alpha-zearalenol (alpha-ZEL), ZEN-14-sulfate, alpha-ZEL-sulfate, ZEN-14-glucoside, and ZEN-16-glucoside in tempeh production. alpha-ZEL, being significantly more toxic than ZEN, was the main metabolite in most of the Rhizopus incubations, while in Aspergillus oryzae fermentations ZEN-14-sulfate was predominantly formed. Additionally, two of the 14 authentic samples were contaminated with ZEN, alpha-ZEL and ZEN-14-sulfate, and in two further samples, ZEN and alpha-ZEL, were determined. Consequently, tempeh fermentation of ZEN-contaminated maize/soybean mixture may lead to toxification of the food item by formation of the reductive ZEN metabolite, alpha-ZEL, under model as well as authentic conditions.