VAAM-Jahrestagung 2011 Karlsruhe, 3.–6. April 2011

species of marine macroalgae of the German Wadden Sea and the SpanishAtlantic coast of Galicia. The presence and diversity of Roseobacters on thedifferent algae was analysed by using a Roseobacter clade-specific 16Sribosomal RNA gene-based PCR-DGGE approach. Our results revealedpresence of a variety of Roseobacter on all investigated algal species.Furthermore, we detected different compositions of Roseobacters on alldifferent macroalgae. This indicates a species specific relationship betweenthese bacteria and the algae. In addition to the use of molecular biologicalmethods, new strains affiliated to the Roseobacter-clade were isolated fromthe algae for further analysis of the relationship between the algae and thebacteria. Since production of secondary metabolites was reported previouslyfor Roseobacters obtained from macroalgae, the isolates were tested forproduction of antibiotic compounds and compared to isolates obtained fromthe water column.EMP122A simple time-resolved microdilution assay fordetermination of dynamic microbial growth inhibition bymetal nanoparticlesV.S. Schacht*, L. Neumann, N. Sahragard, V. Cheunuie-Ambe, S. Schnell,M. BungeInstitute of Applied Microbiology, Justus-Liebig-University, Giessen,GermanyEngineered metal- and metal-oxide nanoparticles are increasingly used inproducts for everyday life and comprise additives that exhibit advantageousantimicrobial properties. Once released into the environment, it is expectedthat several types of metal nanoparticles could possess adverse effects onmicrobes of exceeding environmental importance. However, existingstandard ecotoxicological methods are only of limited applicability forstudying the whole spectrum of potential nanoparticle impacts on microbiallife.Agar diffusion tests could be successfully adapted to test the microbialsusceptibility to noble metal nanoparticles (Pd, Pt) but testing Ag(0)nanoparticles led to methodological difficulties and required the addition ofdispersive and stabilizing agents such as polysorbate detergents.Nanoparticle transport, biosorption, toxic effects and microbial resistancemechanisms are subject to temporal relatedness and will thus largely affectmicrobial growth dynamics. Therefore, a common microdilution assay wasmodified to allow simultaneous cultivation and real-time analysis ofmicrobial growth inhibition. The automated assay in 96-well microtiterplates combines high temporal resolution with the analysis of manyreplicates. It comprises analysis by MATLAB which is used to numericallydetermine the maximum slope of Gompertz functions fitted to microbialgrowth curves. Test organisms including Cupriavidus necator H16, E. coli,and Pseudomonas putida exhibited different susceptibility to stabledispersions of metal and metal-oxide nanoparticles (Ag, Pd, Ni, ZnO, TiO 2,CuO, ZrO 2, CeO 2), with Ag(0) nanoparticles (D90 < 15 nm) as mosteffective against Gram-negative bacteria. Ag(0) concentrations above 0.008% (w/v) demonstrated complete and irreversible inhibition of microbialgrowth, whereas extended lag phases and partial growth inhibition wasobserved at Ag(0) concentrations between 0.001 and 0.008 %. In contrast,Bacillus spp. revealed up to ten-fold lower sensitivity against Ag(0)nanoparticles. This effect was independent from primary particle sizedistribution suggesting interference by nanoparticle reaggregation in growthmedia, or cross effects induced by Ag + ions released from the surface of thetested materials.Extending our study to complex microbial communities from activatedsludge requires the application of molecular fingerprinting methods andstate-of-the-art metabolic-pattern analysis by proton transfer reaction massspectrometry (PTR-MS). These techniques are used to follow the temporaldynamics of community structure and function and will contribute to a betterunderstanding of antimicrobial activity of metal nanoparticles and their fatein the environment.EMP123High CO 2 concentrations negativly effect methanogenesisand sulfate reduction in gas fields of the North GermanPlainJ. Frerichs* 1 , C. Gniese 2 , N. Hoth 3 , M. Krüger 11 BGR, Geomicrobiology, Hannover, Germany2 Institute of Biological Sciences, University of Mining and Technology,Freiberg, Germany3 Institute of Drilling Technology and Fluid Mining, University of Miningand Technology, Hannover, GermanyIn consequence of their global warming potential, large-scale solutions areneeded to reduce the emission of greenhouse gases such as CO 2 or CH 4 . TheCarbon Capture and Storage (CCS) technique offers one option to reduceemissions. Favourable CO 2 storage sites are depleted gas and oil fields. Ourstudy is focusing on the direct influence of high CO 2 concentrations on theautochthonous microbial population and environmental parameters in suchpotential storage sites.The investigated reservoir formation (Schneeren) is operated by Gaz deFrance Suez E&P DEUTSCHLAND GmbH. The conditions in the reservoirdiffered between the studied wells A and B in various geochemical andmicrobiological parameters. Based on these results our study included bothcultivation and molecular biological approaches.The two production fluids (wells A and B) differed in the dominatingmicrobial activity for indigenous fluids and substrate amended enrichments.Methanogenis was strongly induced after the addition of various substrateswith higher rates for fluids of well A. On the other hand were the highestinduced sulfate reduction activity detected in hydrogen amended fluids ofwell B. Results of the molecular biological analysis of the original fluidssupported the activity data for both fluids. The abundance of archaeal 16SrDNA and mrcA was several magnitudes higher in fluids of well A whereaswell B was dominated by Bacteria.Incubations with high CO 2 concentrations showed a significant decrease ofmethane and sulfide production with increasing CO 2 levels. In a second stepenrichments from the reservoir fluids and pure cultures of referenceorganisms were incubated under in situ pressure and temperature withelevated CO 2. During the short term incubation these experiment showed nodetectable sulfate reduction activity while the total cell number was stable.Further molecular based analysis revealed witch parts of the Schneerencommunity can survive high CO 2 partial pressures in the incubations. Inconclusion this study of simulated CCS operations will provide informationabout possible biogeochemical and microbiological changes during thestorage of CO 2.EMP124Microbial induced mineral precipitation and corrosion ingeothermal plantsA. Westphal*, S. Lerm, M. Alawi, H. WürdemannGerman Research Center for Geosciences, International Center forGeothermal Research, Potsdam, GermanyThe development of renewable energy sources such as geothermal energy isof increasing importance to secure a sustainable energy supply and areduction of greenhouse gas emission to the atmosphere at the same time.For an efficient and permanent reliable use of geothermal energy theinterruption of operation due to malfunction of the facility has to beprevented.Up to now only a few studies focus on microbial induced processes thatcould influence the operational reliability of geothermal plants. Ageothermally used groundwater system was investigated under microbial,geochemical, mineralogical and petrological aspects. The monitoredgroundwater system is located in the North German Basin, Germany. Tocharacterize the microbial biocenosis of a seasonal heat storage fluid andfilter samples were taken from regularly and shift as well as disturbed plantoperation and analyzed based on 16S rDNA. Among fingerprinting methods(SSCP, DGGE) for the characterization of the microbial biocenosis, FISHwill be applied for the quantification of microorganisms and thedetermination of their metabolic activity. The identification ofmicroorganisms enables the correlation to metabolic classes and providesinformation about biochemical processes in the used groundwater system.First results of analyses of the influence of the operational mode on thenumber of cells and the metabolic activity will be presented. Indicatororganisms, which can be useful for an early detection of plant failures, willbe identified, if possible.spektrum | Tagungsband 2011