TY - JOUR A1 - Braetz, S. A1 - Nordholt, Niclas A1 - Nerlich, A. A1 - Schreiber, Frank A1 - Tedin, K. A1 - Fulde, M. T1 - TisB enables antibiotic tolerance in Salmonella by preventing prophage induction through ATP depletion N2 - Antibiotic persistence comprises drug-tolerant bacteria that can survive treatment with antibacterial agents, despite lacking classical genetic resistance mechanisms. Therefore, persisters are clinically relevant because they can lead to treatment failures and chronic infections. Additionally, antibiotic persistence facilitates the evolution of resistance through genetic mutations. Persisters are triggered by a lack of nutrients, bacterial toxins, low ATP levels, or other stress responses that shut down bacterial metabolism. However, the involvement of prophages, viruses that integrate into bacterial chromosomes, is less well understood. In this study, we tested a tisAB deletion in Salmonella Typhimurium and examined persister cell formation following treatment with the DNA-damaging drug ciprofloxacin. TisB is a bacterial toxin that increases the influx of protons across the inner bacterial membrane into the cytosol, causing ATP depletion. We demonstrate that the deletion of tisAB increases prophage induction and bacterial killing, leading to a reduced persister cell fraction. The tisAB mutant is unable to down regulate its ATP concentration after exposure to ciprofloxacin, which in turn allows for stronger binding of RecA to single-stranded DNA, the activator of both the SOS response and prophage induction. KW - Antimicrobial resistance KW - Bacterial survival mechanisms KW - Escherichia coli KW - Salmonella typhimurium PY - 2025 DO - https://doi.org/10.1371/journal.ppat.1013498 IS - 9 SP - 1 EP - 23 AN - OPUS4-64642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Valentin, Jules D. P. A1 - Altenried, Stefanie A1 - Varadarajan, Adithi R. A1 - Ahrens, Christian H. A1 - Schreiber, Frank A1 - Webb, Jeremy S. A1 - van der Mei, Henny C. A1 - Ren, Qun T1 - Identification of Potential Antimicrobial Targets of Pseudomonas aeruginosa Biofilms through a Novel Screening Approach N2 - Pseudomonas aeruginosa is an opportunistic pathogen of considerable medical importance, owing to its pronounced antibiotic tolerance and association with cystic fibrosis and other life-threatening diseases. The aim of this study was to highlight the genes responsible for P. aeruginosa biofilm tolerance to antibiotics and thereby identify potential new targets for the development of drugs against biofilm-related infections. By developing a novel screening approach and utilizing a public P. aeruginosa transposon insertion library, several biofilm-relevant genes were identified. The Pf phage gene (PA0720) and flagellin gene (fliC) conferred biofilm-specific tolerance to gentamicin. Compared with the reference biofilms, the biofilms formed by PA0720 and fliC mutants were completely eliminated with a 4-fold-lower gentamicin concentration. Furthermore, the mreC, pprB, coxC, and PA3785 genes were demonstrated to play major roles in enhancing biofilm tolerance to gentamicin. The analysis of biofilm-relevant genes performed in this study provides important novel insights into the understanding of P. aeruginosa antibiotic tolerance, which will facilitate the detection of antibiotic resistance and the development of antibiofilm strategies against P. aeruginosa. KW - Antimicrobial resistance KW - Bacteria KW - Biofilms KW - Pseudomonas aeruginosa PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-570205 DO - https://doi.org/10.1128/spectrum.03099-22 SP - 1 EP - 5 PB - ASM Journals AN - OPUS4-57020 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schreiber, Frank A1 - Zimmermann, M. A1 - Escrig, S. A1 - Lavik, G. A1 - Kuypers, M.M.M. A1 - Meibom, A. A1 - Ackermann, M. T1 - Substrate and electron donor limitation induce phenotypic heterogeneity in different metabolic activities in a green sulphur bacterium N2 - Populations of genetically identical cells can display marked variation in phenotypic traits; such variation is termed phenotypic heterogeneity. Here, we investigate the effect of substrate and electron donor limitation on phenotypic heterogeneity in N2 and CO2 fixation in the green sulphur bacterium Chlorobium phaeobacteroides. We grew populations in chemostats and batch cultures and used stable isotope labelling combined with nanometer‐scale secondary ion mass spectrometry (NanoSIMS) to quantify phenotypic heterogeneity. Experiments in H2S (i.e. electron donor) limited chemostats show that varying levels of NH4+ limitation induce heterogeneity in N2 fixation. Comparison of phenotypic heterogeneity between chemostats and batch (unlimited for H2S) populations indicates that electron donor limitation drives heterogeneity in N2 and CO2 fixation. Our results demonstrate that phenotypic heterogeneity in a certain metabolic activity can be driven by different modes of limitation and that heterogeneity can emerge in different metabolic processes upon the same mode of limitation. In conclusion, our data suggest that limitation is a general driver of phenotypic heterogeneity in microbial populations. KW - NanoSIMS KW - Phenotypic heterogeneity PY - 2018 UR - https://onlinelibrary.wiley.com/doi/abs/10.1111/1758-2229.12616 DO - https://doi.org/10.1111/1758-2229.12616 SN - 1758-2229 VL - 10 IS - 2 SP - 179 EP - 183 PB - John Wiley & Sons Ltd AN - OPUS4-44596 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Block, S. A1 - Boß, K.-H. A1 - Frobese, D.-H. A1 - Pape, H. A1 - Gösslinghoff, L. A1 - Grossepieper, T. A1 - Kasper, R. A1 - Kirchner, W. A1 - Kollmann, P. A1 - Kröger, P. A1 - Ringlstetter, P. A1 - Kuska, T. A1 - Mattejat, K. A1 - Niehüser, H. A1 - Pfeiffer, F. A1 - Pötzsch, Klaus-Michael A1 - Jochems, Frank A1 - Schäfer, H. A1 - Vogt, W. A1 - Zankl, C. A1 - Ludzay, J. T1 - Empfehlungen zur Vermeidung von Überdrücken an Tankfahrzeugen bei Untenbefüllung N2 - Das Risiko von Überdrücken bei der Untenbefüllung von Tankfahrzeugen hat zu Vorfällen mit zum Teil erheblichen Sach- und Personenschäden geführt und ist ein nicht auszuschließendes Gefährdungspotential für Menschen, Umwelt, Anlagen und Transportmittel. Zur weiteren Verbesserung des Managements dieses Risikos und seiner potentiellen Auswirkungen hat der MWV die DGMK gebeten, das Thema in einem Projekt zu bearbeiten, um mögliche Sicherungsdefizite aufzudecken und Lösungsmöglichkeiten aufzuzeigen. Als Forschungsstelle wurde die Physikalisch-Technische Bundesanstalt (PTB) ausgewählt, die das DGMK-Projekt 727 „Überdrucksicherung an Tankfahrzeugen“ gemeinsam mit Vertretern von Tankfahrzeug- und Armaturenherstellern, Mineralölindustrie sowie der Bundesanstalt für Materialforschung und -prüfung (BAM) bearbeitet hat. In Messungen an zwei Füllstellen wurden reale Druck-, Temperatur- und Volumenstromverhältnisse für die Beladung eines Tankfahrzeugs aufgenommen. Es wurde festgestellt, dass es in einem Tankfahrzeug, in dem keine zusätzlichen Druckverluste wie z. B. durch Vereisungen im Inneren der Kippventil-Flammendurchschlagsicherungs-Armatur auftreten, zu keinem unzulässig hohen Druckaufbau in einer Tankwagenkammer kommen kann. Zusätzlich erfolgten Versuche in einer Kältekammer, um die Möglichkeit und die Randbedingungen einer Vereisung des Kippventils und der Flammendurchschlagsicherung zu ermitteln. Mit diesen Ergebnissen sind Szenarien erarbeitet worden, die bekannte Überdruckschadensereignisse erklären können. Aus einer Gefährdungsbeurteilung heraus wurden Maßnahmen beschrieben, wie zukünftig solche Überdruckschäden an Tankfahrzeugen vermieden werden können. Aufbauend auf den Ergebnissen des Projektes hat die Projektbegleitung diese und weitere Maßnahmen hinsichtlich ihrer Umsetzbarkeit diskutiert und die vorliegende Empfehlung zur Vermeidung von Überdrücken an Tankfahrzeugen bei Untenbefüllung erarbeitet. KW - Untenbefüllung KW - Tankfahrzeuge KW - Überdruck KW - Mineralöl KW - Sicherheitsventile PY - 2012 VL - 727 IS - 3 SP - 1-4 EP - Anl. 1-3 AN - OPUS4-27921 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bauer, L.J. A1 - Wieder, Frank A1 - Truong, V. A1 - Förste, F. A1 - Wagener, Y. A1 - Jonas, A. A1 - Praetz, S: A1 - Schlesiger, C. A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Kanngießer, B. A1 - Zaslansky, P. A1 - Mantouvalou, I. T1 - Absorption Correction for 3D Elemental Distributions of Dental Composite Materials Using Laboratory Confocal Micro-X-ray Fluorescence Spectroscopy N2 - Confocal micro-X-ray fluorescence (micro-XRF) spectroscopy facilitates three-dimensional (3D) elemental imaging of heterogeneous samples in the micrometer range. Laboratory setups using X-ray tube excitation render the method accessible for diverse research fields but interpretation of results and quantification remain challenging. The attenuation of X-rays in composites depends on the photon energy as well as on the composition and density of the material. For confocal micro-XRF, attenuation severely impacts elemental distribution information, as the signal from deeper layers is distorted by superficial layers. Absorption correction and quantification of fluorescence measurements in heterogeneous composite samples have so far not been reported. Here, an absorption correction approach for confocal micro-XRF combining density information from microcomputed tomography (micro-CT) data with laboratory X-ray absorption spectroscopy (XAS) and synchrotron transmission measurements is presented. The energy dependency of the probing volume is considered during the correction. The methodology is demonstrated on a model composite sample consisting of a bovine tooth with a clinically used restoration material. KW - Micro X-ray fluorescence spectroscopy KW - Dental composite materials KW - Computed tomography KW - Absorption correction PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601630 DO - https://doi.org/10.1021/acs.analchem.4c00116 SN - 0003-2700 SN - 1520-6882 VL - 96 IS - 21 SP - 8441 EP - 8449 PB - American Chemical Society Publications CY - Washington, DC AN - OPUS4-60163 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -