TY - CONF A1 - Zubia Aranburu, Judith A1 - Cappella, Brunero A1 - Zabala Eguren, A. A1 - Buruaga Lamarain, L. A1 - Aginagalde Lopez, A. A1 - Bonse, Jörn A1 - Schwibbert, Karin T1 - Quantification of the adhesion force of E. coli on Ti via single-cell force spectroscopy N2 - Antibiotic resistance is a growing global problem which poses a massive threat to human health. Although human activity contributes to the acceleration of the process, bacteria have a self-driven stabilisation mechanism to protect themselves from such and other external threats: biofilm formation. Nonetheless, it is the adhesion of a single bacterial cell to a surface that triggers the formation of such network of biomolecules and microorganisms, as well as its hazardous consequences. The main objective of this work was to quantify the adhesion force of a single E. coli cell on a Ti substrate via the AFM-related single-cell force spectroscopy, with both the cell and the substrate material being of high clinical relevance. A set of 25 x 25 force displacement curves was acquired with a maximum force of 3.2 nN without dwell time, yielding a topography map and an adhesion force map that showed to be correlated. A mean adhesion force of 0.85 ± 0.175 nN was measured and the presence of cell appendages on the bacterial cell wall was verified through individual force-displacement curves. Bacterial viability was assessed after the measurements via live/dead staining. T2 - XL Congreso Anual de la Sociedad Española de Ingeniería Biomédica CASEIB 2022 CY - Valladolid, Spain DA - 23.11.2022 KW - Bacteria KW - Atomic force microscopy KW - Force distance curve PY - 2022 SN - 978-84-09-45972-8 SP - 217 EP - 220 AN - OPUS4-57039 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Xu, Yong A1 - Huang, Yanliang A1 - Yang, D. A1 - Kunte, Hans-Jörg A1 - De Marco, R. A1 - Wang, X. T1 - Investigation of the calcareous deposits formation controlled by interfacial pH and its effect on the hydrogen entry into AISI 4135 steel in seawater N2 - The influence of interfacial pH between AISI 4135 steel and seawater under different polarization potentials on the formation of calcareous deposits has been studied. An interfacial pH of 9.61 at −0.9 V vs. SCE using state of the art iridium oxide microelectrode was found to be the critical pH for the precipitation of magnesium hydroxide. Calcareous deposits with a double-layer structure comprising an inner-brucite layer and an outer-aragonite layer were found to form at potentials between −1.0 V and −1.2 V vs. SCE. Furthermore, the facilitation of hydrogen permeation into steel induced by the formation of calcareous deposits was verified using the Devanathan-Stachurski electrochemical test. The mechanism of calcareous deposits facilitates hydrogen permeation into steel is related to its inhibition on hydrogen recombination and escape processes. KW - Low alloy steel KW - Cathodic protection KW - Calcareous deposits KW - Hydrogen permeation PY - 2020 DO - https://doi.org/10.1016/j.ijhydene.2020.11.040 SN - 0360-3199 SP - 1 EP - 18 PB - Elsevier Ltd. AN - OPUS4-51730 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wen, Keqing A1 - Gorbushina, Anna A1 - Schwibbert, Karin A1 - Bell, Jérémy T1 - A microfluidic platform for monitoring biofilm formation in flow under defined hydrodynamic conditions N2 - Bacterial adhesion on surfaces of medical, water and food applications may lead to infections, water or food spoilage and human illness. In comparison to traditional static and macro flow chamber assays for biofilm formation studies, microfluidic chips allow in situ monitoring of biofilm formation under various flow regimes, have better environment control and smaller sample requirements. In this work, a novel microfluidic platform is developed to investigate biofilm adhesion under precisely controlled bacteria concentration, temperature, and flow conditions. This platform central unit is a single-inlet microfluidic flow cell with a 5 mm wide chamber designed and tested to achieve ultra-homogenous flow in the central area of chamber. Within this area, defined microstructures are integrated that will disturb the homogeneity of the flow, thus changing bacterial adhesion pattern. Here we present the monitoring of bacterial biofilm formation in a microfluidic chip equipped with a microstructure known as micro-trap. This feature is based on a 3D bacteria trap designed by Di Giacomo et al. and successfully used to sequester motile bacteria. At first, fluorescent particles similar in size to Escherichia coli (E. coli) are used to simulate bacteria flow inside the flow cell and at the micro-trap. The turbulences induced by the trap are analyzed by imaging and particle tracking velocimetry (PTV). Secondly, the model strain E. coli TG1, ideal and well described for biofilm studies, is used to analyze biofilm formation in the micro-trap. Therefore, a stable fluorescent strain E. coli TG1-MRE-Tn7-141 is constructed by using Tn7 transposon mutagenesis according to the method described by Schlechter et al. Sequestering of E. coli cells within the micro-trap was followed using epifluorescence microscopy. The novel microfluidic platform shows great potential for assessment of bacterial adhesion under various flow regimes. The performance of structural feature with respect to the generation of turbulences that promote or reduce bacterial adhesion can be systematically examined. The combination of flow analysis and fluorescent strain injection into the microfluidic chip shows that the micro-trap is useful for capturing bacteria at defined positions and to study how flow conditions, especially micro-turbulences, can affect biofilm formation. It represents a powerful and versatile tool for studying the relation between topography and bacteria adhesion. T2 - International Conference on Miniaturized Systems for Chemistry and Life Sciences CY - Katowice, Poland DA - 15.10.2023 KW - Biofilm KW - E. coli KW - Microfluidics KW - Velocimetry KW - Fluorescence PY - 2023 AN - OPUS4-59593 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wen, Keqing T1 - In situ analysis of biofilm formation under different flow regimes with the help of a microfluidic platform N2 - Bacteria often live in habitats characterized by fluid flow, which is ubiquitous in a diverse range of environments such as surface waters, wastewater treatment facilities, pipelines, and medical implants. Bacterial adhesion on surfaces may lead to biocorrosion and biodegradation. In comparison to traditional static and macro flow chamber assays for biofilm formation studies, microfluidic chips allow in situ monitoring of biofilm formation and biofilm related gene expression under various flow regimes. We developed a complete microfluidic platform to investigate biofilms under precisely controlled flow conditions. This platform central unit is a single-inlet microfluidic flow cell with a 5 mm wide chamber tested and analyzed by imaging tracking velocimetry (PIV) to achieve ultra-homogenous flow in the central area of the chamber. Additionally, dedicated microstructures were introduced to the chamber’s center to favor and localize bacterial adhesion and biofilm formation pattern. The flows and vortices induced by the structure were analyzed by computational fluid dynamics (CFD) and related to shape and dimension of the biofilm formed by Escherichia coli TG1. The major proteinaceous component of E. coli biofilms are extracellular amyloid fibers (curli) consisting of major (CsgA) and minor (CsgB) subunits. We used the promotor probe plasmid pRU1701 to monitor csgB-promotor activity under different flow regimes in complex and minimal medium. For comparison, csgB promotor activity in a batch liquid culture and curli production on LB and M9 agar plates were assessed. The microfluidic platform represents a powerful and versatile tool for studying biofilm in flow. The setup shows great potential for the yet not too much explored in flow monitoring of biofilm formation and related gene expression under hydrodynamic stresses. T2 - International Biodeterioration and Biodegradation Symposium (IBBS) 19 CY - Berlin, Germany DA - 09.09.2024 KW - Microfluidics KW - Biofilm KW - Escherichia coli KW - Curli PY - 2024 AN - OPUS4-61911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Usmani, Shirin T1 - Wood treated with nano metal fluorides - relations between composition, size, and durability N2 - In this study, nanoscopic particles of magnesium Fluoride (MgF2) and calcium fluoride (CaF2) also known as nano metal fluorides (NMFs), were evaluated for their potential to improve wood durability. Even though these fluorides are sparingly soluble, their synthesis in the form of nano-sized particles turns them into promising candidates for wood preservation. Their distinct property of low-water solubility is proposed to maintain long-lasting protection of treated wood by reducing the leaching of fluoride. Analytical methods were used to characterize the synthesized NMFs and their distribution in treated wood specimens. Transmission electron microscopy images showed that these fluoride particles are smaller than 10 nm. In nano metal fluoride (NMF) treated specimens, aggregates of these particles are uniformly distributed in the wood matrix as confirmed with scanning electron microscopy images and their corresponding energy-dispersive X-ray spectroscopy maps. The fluoride aggregates form a protective layer around the tracheid walls and block the bordered pits, thus reducing the possible flow path for water absorption into wood. This is reflected in the reduced swelling and increased hydrophobicity of wood treated with NMFs. The biocidal efficacy of NMFs was tested against brown-rot fungi (Coniophora puteanaand Rhodonia placenta), white-rot fungus (Trametes versicolor), and termites (Coptotermes formosanus). The fungal and termite tests were performed in accordance with the EN 113 (1996) and EN 117 (2012) standards, respectively. Prior to fungal tests, the NMF treated wood specimens were leached according to the EN 84 (1997)standard. Compared to untreated specimens, the NMF treated wood specimens have a higher resistance to decay caused by brown-rot fungi, white-rot fungus, and termites. Although all NMF treatments in wood reduce the mass loss caused by fungal decay, only the combined treatment of MgF2 and CaF2 has efficacy against both brown-rot fungi and white-rot fungus. Similarly, wood treated with the combined NMF formulation is the least susceptible to attack by C. formosanus.It is proposed that combining MgF2 and CaF2changes their overall solubility to promote the release of fluoride ions at the optimal concentration needed for biocidal efficacy against fungi and termites. In this thesis, it was proven that even after leaching, sufficient fluoride was present to protect NMF treated wood from fungal decay. This shows that NMFs are robust enough for above ground contact outdoor applications of wood, where permanent wetness cannot be avoided according to Use Class 3.2, as per the EN 335 (2013) standard. Also, they pose a low risk to human health and the environment because they are sparingly soluble. Since NMFs significantly reduce the decay of wood, the CO2 fixed in it will be retained for longer than in unpreserved wood. Overall, the novel results of this study show the potential of NMFs to increase the service life of building materials made from non-durable wood. KW - Termites KW - Nano metal fluorides KW - Solubility KW - Wood protection KW - Fungi PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-525108 DO - https://doi.org/10.18452/22553 SP - i EP - 118 PB - Humboldt-Universität zu Berlin CY - Berlin AN - OPUS4-52510 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ulbricht, Alexander T1 - Do Microbes like Additively Manufactured Aluminium? First Details of a Corrosion Test using Sulphate-Reducing Bacteria N2 - Additively manufactured metals become relevant for industrial application. Although many studies on wet corrosion of these metals have been conducted, to the authors knowledge no study seems to contain microbiological corrosion (MIC). In the presented study an experiment was conducted on PBF-LB/AlSi10Mg to test this material's susceptibility for MIC. The tested specimen were analysed using Computed Tomography before and after the MIC experiment to enable a detailed characterisation the damage on the specimens' global and local level. A global reduction of material was observed. In addition, localised damage along process inherent features of the materials microstructure was observed. T2 - Beiratssitzung TF Umwelt CY - Berlin, Germany DA - 17.03.2025 KW - Computed Tomography KW - Additive Manufacturing KW - Biocorrosion KW - Sulphate-reducing Bacteria KW - Microbially influenced corrosion PY - 2025 AN - OPUS4-62772 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ulbricht, Alexander T1 - Do Microbes like Additively Manufactured Aluminium? N2 - The use of laser-additively manufactured metallic components in the industrial sector is gaining traction, with the process now entering its application phase. Consequently, the materials are exposed to corrosive microbes, which this study examines in order to determine the implications of this exposure. Specifically, the study examines the exposure of laser powder bed fused AlSi10Mg (PBF-LB/AlSi10Mg) components to sulphate-reducing bacteria in an anaerobic environment. Is the specific PBF-LB microstructure a potential factor in determining or aiding biocorrosion? A prismatic specimen was exposed to sulphate-reducing bacteria (SRB) for two weeks. The sample was scanned by X-ray computed tomography (XCT) before and after SRB exposure. The two data sets were registered to each other (using the internal void distribution as markers, due to the corrosion of the specimen’s surface) to enable the evaluation of the corrosion damage. Virtual cuts of the 3D XCT reconstructions show a loss of volume and localised damage. The damage distribution aligns with the hatching pattern of laser exposure from laser powder bed fusion. T2 - Konferenz iCT 2026 CY - Linz, Austria DA - 10.02.2026 KW - Computed tomography KW - Biokorrosion KW - Additive manufacturing KW - PBF-LB KW - Laser powder bed fusion KW - Sulphate-reducing bacteria PY - 2026 AN - OPUS4-65570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Taghavi Kalajahi, Sara T1 - The effectiveness of cathodic protection (CP) on microbiologically influenced corrosion (MIC) control N2 - Cathodic protection (CP) is an electrochemical method, to manage corrosion in different industries, especially in buried and sub-merged environments. In those environments microorganisms are present and can affect the corrosion process and cause microbiologically influenced corrosion (MIC). Most of the industry standards recommend performing CP using -800 mV (Ag/AgCl), however, if microorganisms capable of initiating MIC are present, for instance sulfate reducing bacteria (SRB), it is recommended to use even more negative potentials. It is assumed that this will provide adequate protection of the metal. Currently there is no information or valid data in the context of CP, on the level of MIC threat and the extent to which more negative potentials can be used to provide adequate protection and not over-protection (due to hydrogen embrittlement threat). Conflicting statements can be found in the literature regarding the effectiveness of CP on MIC, from reducing biofilm attachment to increasing bacterial activity and biofilm attachment. Recently, the development and lower price of molecular microbiological methods (MMM) have opened the door for more effective studies of MIC mechanisms along with other electrochemical methods and surface analysis. In this work, the genetic functionality of biofilms formed in the laboratory under CP conditions is investigated using transcriptomics. Gene expression of SRB biofilms under different CP potentials (-800, -850 and -900 mV) will be studied; comparison with control will allow us to distinguish the specific genes that are differentially expressed, leading to a better understanding of the mechanism of CP to affect bacterial activity and diversity. Keywords - cathodic protection, microbiologically influenced corrosion, molecular microbial methods. T2 - IBBS CY - Berlin, Germany DA - 09.09.2024 KW - Microbiologically influenced corrosion PY - 2024 AN - OPUS4-61981 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Stephan, Ina A1 - Boenke, Viola A1 - Drecker, Sigrid T1 - Weiterentwicklung und Verbesserung des Konzeptes zur Begrenzung von Konservierungsmitteln für Produkte mit dem Blauen Engel N2 - Im Rahmen des Forschungsvorhabens wurde die biologische Prüfmethode der Checkliste zur stoffli-chen Bewertung im Rahmen des Aufnahmeverfahrens für weitere Topfkonservierungsmittel in den Anhang 1 zur Vergabegrundlage RAL-UZ102 „Emissionsarme Innenwandfarben“ überarbeitet. Der Test für den Einsatz von Konservierungsmitteln in seiner jetzigen Fassung besteht seit nahezu 20 Jah-ren und erfolgt ausschließlich an weißer Dispersionsfarbe für den Innenraum. Die hierbei ermittelten Höchstmengen für den Einsatz von Topfkonservierern werden z.Zt. auch auf andere Innenraumbau-produkte übertragen. Ziel war es zu klären, ob die Anforderungen an die Topfkonservierung bei Far-ben tatsächlich für andere Innenraumbauprodukte übernommen werden können. Die im Vorhaben durchgeführten Versuche deuten darauf hin, dass dies nicht ohne weiteres möglich ist. Nach Rückspra-che mit Vertretern aus der Industrie wurde das Keimspektrum für die Prüfung zudem um Hefe- und Schimmelpilze erweitert. Des Weiteren wurde eine künstliche Alterung eingeführt und überprüft, ob dies einen Einfluss auf den Gehalt an Isothiazolinonen hat. Die Konzentration von Isothialzolinonen wurde mittels Ultra-Hochleistungsflüssigkeitschromatographie kontrolliert und hinsichtlich einer Kor-relation mit dem Wachstum von Mikroorganismen ausgewertet. Da die in den Innenraumbauproduk-ten zugesetzten Isothiazolinone als Kontaktallergene bekannt sind, ist es ein Ziel des „Blauen Engel“-Umweltzeichens, die geringste erforderliche Menge an Konservierungsmittel in den Produkten zu ver-wenden, ohne die positive Auswirkung der Topfkonservierung zu gefährden. Daher sind die Optimie-rung der Leistungsstärke von Konservierungsmitteln und die Kontrolle der Hygiene im Herstellungs-prozess von zunehmender Bedeutung. Um Einblicke in den Herstellungsprozess von Farben zu gewin-nen, wurden im Rahmen des Vorhabens vier Farbwerke besichtigt, in denen weiße Innenraumfarben produziert werden, die mit dem Umweltzeichen „Blauer Engel“ ausgezeichnet sind. Gemeinsam mit den Fachleuten vor Ort wurde diskutiert, welche Maßnahmen zur Verbesserung der Werkshygiene er-griffen werden können, um den Einsatz von Topfkonservierern möglichst gering zu halten. Des Weite-ren wurde in dem Forschungsvorhaben untersucht, ob eine schnellere Bestimmung der Keimzahl in den Rohstoffen mittels quantitativer Polymerasekettenreaktion bereits im Farbwerk realisierbar ist. KW - Methode KW - Isothiazolinone KW - Gebindekonservierung KW - Bakterien KW - Schimmel KW - Wirksamkeit KW - Biozide PY - 2020 SN - 1862-4804 VL - 54 SP - 4 EP - 149 PB - Umweltbundesamt CY - Dessau AN - OPUS4-50972 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sobisch, Lydia-Yasmin T1 - Identification of Genes Involved in Susceptibility to Biocides in Sulfate-Reducing Bacteria N2 - Microbially induced corrosion (MIC) poses a significant challenge in various industries, leading to structural damage and economic losses due to the activity of microorganisms on metal surfaces. The major culprits of MIC are the sulfate-reducing bacteria (SRB). A common mitigation method is the usage of biocides to prevent MIC. However, the molecular mechanisms that determine susceptibility of SRB to biocides have been poorly understood. Our aim is to identify genes that are linked to biocide susceptibility in the model SRB strain Oleidesulfovibrio alaskensis (G20). We investigated the susceptibility of G20 towards three biocides commonly used in MIC protection: benzalkonium chloride (BAC), glutaraldehyde (GTA), and tetrakishydroxymethyl phosphonium sulphate (THPS). We determined selection of mutants in specific genes in two G20 barcoded transposon mutant libraries in the presence of these biocides and media as control along a concentration gradient up to 500 ppm. Our study investigated over 1843 genes in G20, revealing insights into their response to biocide treatments. We identified 1668 genes negatively affected by biocide treatment, while 175 genes showed improved fitness. Among the treatments leading to reduced fitness in the mutants, GTA had the highest number of solely negatively affected genes (186), followed by BAC (67) and THPS (69). There were common negative impacts on 280 genes of all four treatments (BAC, GTA, THPS, control). Notably, BAC and GTA shared 113 affected genes, BAC and THPS shared 59, and GTA and THPS shared 72. On the single gene level, mutants treated with THPS exhibited reduced fitness for the rluD gene (DDE_1447), encoding ribosomal large subunit pseudouridine synthase d, which plays a crucial role in protein biosynthesis. In the presence of BAC, mutants showed reduced fitness due to the lack of the acrB gene (DDE_0401), encoding a cationic efflux pump crucial for biocide resistance. Our findings provide leads for future research into the detailed molecular mechanisms that underlie biocide susceptibility in microorganisms responsible for MIC. Such detailed understanding will enable the development of improved MIC prevention strategies and foster a more sustainable use of biocides. T2 - International Biodeterioration and Biodegradation Symposium CY - Berlin, Germany DA - 09.09.2024 KW - Biocide Resistance KW - Transposon Mutant Libraries KW - Sulfate-Reducing Bacteria (SRB) KW - Microbially Induced Corrosion (MIC) PY - 2024 AN - OPUS4-61526 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -