4 Material und Umwelt
Filtern
Dokumenttyp
- Posterpräsentation (61) (entfernen)
Sprache
- Englisch (61) (entfernen)
Referierte Publikation
- nein (61)
Schlagworte
- Biocides (19)
- Antimicrobial resistance (9)
- Corrosion (9)
- Biofilm (7)
- Methanogens (7)
- Horizontal gene transfer HGT (6)
- Microbiology (6)
- Persistence (6)
- Resistance evolution (6)
- Archaea (5)
Organisationseinheit der BAM
- 4.1 Biologische Materialschädigung und Referenzorganismen (61) (entfernen)
Microbiologically influenced corrosion (MIC) is the deterioration of metals due to the metabolic activities of microorganisms. Microorganisms can take electrons directly from the metal surface (EMIC) thereby causing corrosion. Well known culprits of EMIC are: sulfate-reducing bacteria (SRB), acetogens and methanogens.
Our aims
- Develop a novel flow system to study MIC by methanogens to mimic industrial Environments
- Investigate the inhibitory concentrations of biocides targeting SRB on corrosive methanogenic strains
- Investigate the inhibitory effects of corrosion inhibitors on methanogens
- Compare the inhibitory concentrations to SRB
The halophilic bacterium Halomonas elongata can tolerate salt concentrations above 10% NaCl and uses the accumulation of the compatible solute ectoine as a major osmoregulatory mechanism. Ectoine can be accumalted inside the cell through import from the medium or de novo synthesis and establishes an osmotic equilibrium with the surrounding1. Ectoine also protects proteins from the effects of freezing, drying and high temperatures4 and DNA from ionizing radiation2. These features make ectoine a valuable compound for cosmetics and medical devices.
H. elongata was originally isolated from a solar salt facility, where it thrives under high salt concentrations. It was found that marine prokaryotes, which are exposed to high oxidative stress in their environment, vary glycolytic strategies5. A variation in the use of the glucose metabolic pathways is also assumed for H. elongata.
The halophilic bacterium Halomonas elongata can tolerate salt concentrations above 10% NaCl and uses the accumulation of the compatible solute ectoine as a major osmoregulatory mechanism. Ectoine can be accumalted inside the cell through import from the medium or de novo synthesis and establishes an osmotic equilibrium with the surrounding1. Ectoine also protects proteins from the effects of freezing, drying and high temperatures4 and DNA from ionizing radiation2. These features make ectoine a valuable compound for cosmetics and medical devices.
H. elongata was originally isolated from a solar salt facility, where it thrives under high salt concentrations. It was found that marine prokaryotes, which are exposed to high oxidative stress in their environment, vary glycolytic strategies5. A variation in the use of the glucose metabolic pathways is also assumed for H. elongata.
Biofilm formation on materials leads to high costs in industrial processes, as well as in medical applications. This fact has stimulated interest in the development of new materials with improved surfaces to reduce bacterial adhesion.
We present a flow chamber system to test and quantify bacterial adhesion on materials that are part of antifouling concepts. The adhesion process is standardized and can be adapted to different bacteria in subaquatic of subaerial environments. It is combined with a standardized evaluation procedure based on statistical evidence.
Microbially influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) which act upon the metal by the reactiveness of hydrogen sulfide, and by withdrawal of the available electrons in electrical contact with the metal. Methanogenic archaea are supposed to cause MIC. Because they do not produce hydrogen sulfide, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood. Precipitation of siderite (4Fe + 5HCO3 + 5H+ 4FeCO3 + CH4 + 3H2O) can lead to an insulating layer on the metal surface and lower the corrosion rate. Still, the extent of FeCO3 precipitation may be significantly influenced by environmental conditions such as pH and advective processes.
Microbially influenced corrosion (MIC) of iron is usually attributed to sulfate-reducing microorganisms (SRM) which act upon the metal by the reactiveness of hydrogen sulfide, and by withdrawal of the available electrons in electrical contact with the metal. Methanogenic archaea are supposed to cause MIC. Because they do not produce hydrogen sulfide, withdrawal of electrons may be their main corrosive mechanism; however, mechanistic details and kinetics of the overall process are poorly understood. Precipitation of siderite (4Fe + 5HCO3 + 5H+ 4FeCO3 + CH4 + 3H2O) can lead to an insulating layer on the metal surface and lower the corrosion rate. Still, the extent of FeCO3 precipitation may be significantly influenced by environmental conditions such as pH and advective processes.
Background Bacterial biofilms are regarded as the most common cause of chronic infections and are often associated with medical devices, such as implants and catheters. Bacteria growing in biofilms produce a protective, extracellular matrix, which enables them to tolerate much higher antimicrobial concentrations than free-living bacteria and survive long enough to acquire antimicrobial resistance. Preventive and therapeutic strategies against biofilm infections in clinical settings commonly involve the application of multiple antimicrobials: biocidal coatings on the biomaterials and systemically administered antibiotics. This frequent practice harbors the risk of the development of cross-resistance via shared resistance mechanisms between antimicrobials used in material coatings and administered antibiotics.
Aim Our goal is to determine how bacteria adapt to antimicrobials during biofilm formation on surfaces coated with antimicrobials, how antimicrobial resistance mutations are acquired and evolve within mature biofilms, and how population dynamics within biofilms affect the transmission of resistance mutations. Specifically, we want to identify antimicrobial-antibiotic-combinations that select for and against antibiotic resistance in biofilms by following the population dynamics of resistant and susceptible strains in competition assays.
Methodology We will grow biofilms of Pseudomonas aeruginosa on glass surfaces with and without antimicrobial coatings and expose them to antibiotics. Then we will track their physiological properties, evolutionary adaptations, and population dynamics. First, we will screen in vitro for combinations of antibiotics and antimicrobials that select for and against antibiotic resistance. Second, effective combinations will be chosen for in-depth investigations during bacterial adhesion and of mature biofilms of resistant and susceptible genotypes. Third, based on the outcome of the screen and the obtained mechanistic understanding we will choose a clinical example in which we study the relevance of our findings in biofilms grown in vivo.
Relevance Studying the biointerfacial interactions between bacterial biofilms and medical devices in terms of population dynamics as well as on single cell level during multidrug selection will help us understand how drug resistance develops and spreads in persistent biofilm infections. Based on our findings we aim to provide clinical recommendations for improved administration of antibiotics/antimicrobials in combination with medical device materials in order to mitigate against biofilm associated antimicrobial resistance.
Synchrotron XPS in the soft-X-ray regime is suitable for the detection of light elements commonly found in biological samples. Various model systems of biofilms have been developed and characterised at synchrotron- and lab-based facilities. By obtaining the chemical composition at various information depths, the vertical distribution of iodine in an artificial biofilm have been determined.
Soil microbes are exposed to different environmental stressors originating from various sources. Biocides used as material preservatives can represent environmental stressors since they are in direct contact with the environment including soil. Microorganism in soils can adapt to stress by different mechanisms; for example, by transferring mobile genetic elements via horizontal gene transfer (HGT). Here, we hypothesize that material preservatives can cause increased frequencies of HGT (i.e. altered community permissiveness) facilitating microbial community adaptation to stress. Furthermore, we hypothesize that soil microbial communities are primed by biocide exposure facilitating the response to different types of stresses. We will incubate soil mesocosms with selected biocides to investigate if these compounds promote HGT of plasmids that carry resistance genes in soil microbial communities. Subsequently, we will prime the soil microbial community with sub-inhibitory concentrations of biocides followed by exposure to toxic biocide concentrations or other types of common environmental stresses including metals, antibiotics, and salt. Using suitable control experiments, a shift in the functional response of the primed as compared to the non-primed community would indicate that biocides prime microbial communities via HGT. Together these results will elucidate the effect of biocides on HGT-mediated adaptation to environmental stressors in soil microbial communities.
Soil microbes are exposed to different environmental stressors originating from various sources. Biocides used as material preservatives can represent environmental stressors since they are in direct contact with the environment including soil. Microorganism in soils can adapt to stress by different mechanisms; for example, by transferring mobile genetic elements via horizontal gene transfer (HGT). Here, we hypothesize that material preservatives can cause increased frequencies of HGT (i.e. altered community permissiveness) facilitating microbial community adaptation to stress. Furthermore, we hypothesize that soil microbial communities are primed by biocide exposure facilitating the response to different types of stresses. We will incubate soil mesocosms with selected biocides to investigate if these compounds promote HGT of plasmids that carry resistance genes in soil microbial communities. Subsequently, we will prime the soil microbial community with sub-inhibitory concentrations of biocides followed by exposure to toxic biocide concentrations or other types of common environmental stresses including metals, antibiotics, and salt. Using suitable control experiments, a shift in the functional response of the primed as compared to the non-primed community would indicate that biocides prime microbial communities via HGT. Together these results will elucidate the effect of biocides on HGT-mediated adaptation to environmental stressors in soil microbial communities.
Soil microbes are exposed to different environmental stressors originating from various sources. Biocides used as material preservatives can represent environmental stressors since they are in direct contact with the environment including soil. Microorganism in soils can adapt to stress by different mechanisms; for example, by the evolution of resistance by de novo mutations or acquisition of resistance genes via horizontal gene transfer (HGT). Here, we hypothesize that material preservatives could enhance the evolution of biocide resistance enabling the potential for cross-resistance to antibiotics. Furthermore, we hypothesize that material preservatives can cause increased frequencies of HGT (i.e. altered community permissiveness) facilitating microbial community adaptation to stress. We will culture soil microorganism with increasing concentrations of selected biocides followed by antibiotic susceptibility determination. Moreover, we will incubate soil mesocosms with selected biocides to investigate if these compounds promote HGT of plasmids that carry resistance genes in soil microbial communities. Together these results will elucidate the potential for the evolution of biocide resistance and cross-resistance to antibiotics as well as the effect of biocides on adaptation to environmental stressors in soil microbial communities.