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

Key steps in the isolation of total RNA are low-pH extraction (pH 5.0) andQ-Sepharose chromatography. Depletion of the rRNA content by subtractivehybridization appears to be more reliable than exonuclease treatment [1].The enriched mRNA is of high integrity (RIN > 7) and purity. We currentlyassess different methods to produce cDNA for 454 GS-FLX Titaniumpyrosequencing, in particular with regard to the proportion of rRNA to nonrRNAreads and the average read length. An increase in the average readlength is crucial for accurate functional annotation and taxonomic binning.The direct conversion of mRNA into cDNA without in vitro amplificationappears to be the most promising approach.[1] Mettel et al. (2010) Appl. Environ. Microbiol. 76: 5995-6000.EMP038Effects of elevated CO 2 on microbial communities in nearsurface environmentsS. Gwosdz* 1 , J. Frerichs 1 , J. West 2 , D. Jones 2 , M. Krüger 11 Geochemistry and Raw Materials, Federal Institute for Geosciences andNatural Resources, Hannover, Germany2 British Geological Survey, Keyworth, Nottingham, United KingdomThe reduction of potential greenhouse gas emissions is part of globalstrategies to alleviate the climate change consequences. According to theIntergovernmental Panel on Climate Change (IPCC) report of 2007, thecarbon capture and storage technique (CCS) in deep geological structures(saline aquifers, gas- and oil-fields) can provide a contribution to reduceconflicts between global energy needs and the reduction of greenhouse gasemission. Our study aims at investigating impacts of a potential CO 2 leakagefrom deep reservoirs for near-surface ecosystems. This work is integratedinto the EU funded Project RISCS (Research into Impacts and Safety in CO 2storage) and focuses on natural CO 2 seeps (adapted sites) and non adaptedtest fields like the ASGARD area in Nottingham, England. Natural CO 2seeps located in the Eastern Eifel volcanic field comprising high (90% CO 2),elevated (20%) and background CO 2 concentrations are studied. The effectsof increasing CO 2 in the soil gas content on vegetation profiles and soilchemistry showed clear differences between control and elevated CO 2 site.The overall bacterial and archaeal community size decreased by one order ofmagnitude with increasing CO 2 concentrations, while the abundance offunctional genes involved in anaerobic metabolisms (e.g. dissimilatorysulphate reductase) increased. Both, physiological investigations (activityrates) and molecular biological techniques (DGGE, sequencing) confirmedthe shift towards an anaerobic and acid tolerant community under highconcentrations of CO 2. The non adapted ASGARD area enablesinvestigation of CO 2 effects before, during and after CO 2 exposure,including analysis of adaption mechanisms of pasture and crops. For thispurpose a study of soil and gas chemistry, vegetation profiles, microbialcommunities and activities is conducted. The overall aim, combining resultsfrom both systems, is to estimate effects of CO 2 on microbial and plantcommunities, their recovery time after CO 2 exposure and the detection ofsensitive species. The combined results from both sites will help to revealeffects of CO 2 on near-surface ecosystems, to define thresholds for CO 2levels in the environment and to estimate risks and chances of CO 2 storage.EMP039Characterization of the fungal population in biofilmsJ. Zoller*, R. FischerInstitute for Applied Biosciences, Department of Microbiology, KarlsruheInstitute of Technology (KIT), Karlsruhe, GermanyIt has been recently shown that the majority of microorganisms live inbiofilms as an extremely successful way of life. Only a few microorganismshave a planktonic lifestyle. Biofilms are made of a matrix of organicmolecules (extracellular polymeric substrates - EPS) in whichmicroorganisms are embedded and which offers new habitats to otherorganisms, such as other bacteria or fungi [1]. Bacteria and fungi benefit inthis symbiotic life form of metabolic exchange, protection and geneticflexibility. By taking samples of biofilms from a municipal sewage plant, weisolated several known species from the genus Candida and Trichosporon.The most common species was Galactomyces geotrichum but alsoSaccharomyces cerevisiae and Candida tropicalis. However, sequenceanalysis of the ITS-regions amplified directly from biofilms revealed thepresence of more than 110 so far unknown fungi. Phylogenetic analysesrevealed that most of them are closely related to other species from thegenus Candida and Trichoderma. Investigations whether these fungi arebiofilm-specific are under way. Further comparable analysis betweenbiofilms in lakes, rivers the sewage plant, revealed that the fungalbiodiversity in the latter is larger. We also made fluorescence in situhybridization to analyze the distribution and interaction of fungi and bacteriain biofilms.To understand the life of fungi inside the biofilm we are currently usingFusarium oxysporum. The genome of this fungus is available and he it isreadily found in biofilms [2, 3]. We constructed a strain, which expressesdsRed in nuclei. This will enable us to distinguish this strain in biofilms andquantify the proportion of genetically modified strains in competitionexperiments.[1] Flemming, H. -C. and J. Wingender (2010): The biofilm matrix. Nature Rev. 8: 623-633.[2] Imamura, et al (2008): Fusarium and Candida biofilms on soft contact lenses: model development,influence of lense type, and susceptibility to lens car solutions. Antimicrob. Agents Chemother. 52(1):171-182.[3] Raad, I. and R. Hachem (1995): Treatment of central venous catheter-related fungemia due toFusarium oxysporum. Clin. Infect. Dis. 20(3): 709-711.EMP040Mechanisms for the detoxification of environmentalpollutants by fungiR. Sietmann*, A. Mikolasc 1 , F. SchauerInstitute of Microbiology, Applied Microbiology, Greifswald, GermanyFungi are widespread in the environment, especially in soil where they makeup a great part of the microbial biomass. There, fungi are of particularimportance as they decompose a wide range both of economically usefulproducts (food, wood, cotton) as well as environmental pollutants (gas oil,petroleum, phenols). We have focused our studies on the fungalbiotransformation of persistent and toxic pollutants such as disinfectants andbiarylic compounds (biphenyl, diphenyl ether, dibenzofuran) which consistof one or two aromatic ring systems. Disinfectants increasingly reach theenvironment due to their increasing use in households, as components ofcosmetics, and in industry, in addition to their medical applications. Most ofthe compounds investigated are persistent environmental pollutants andconsiderable effort has been devoted to study the mechanisms of theirbiodegradation and detoxification.In most cases the degradation is initiated by diverse primary oxidation andhydroxylation reactions. One mechanism for detoxification by filamentousfungi involves the formation of conjugates of the hydroxylated intermediatesand their excretion. Our results show that there are other importantdetoxification mechanisms. Thus yeasts are able to cleave the aromatic ringsystem of these compounds. The products formed are muconic acidderivatives as well as the corresponding lactones. Though the pollutants aretoxic to the yeast strains the ring cleavage products are not. Thus, theoxidation of aromatic environmental pollutants up to ring cleavagerepresents another specific detoxification mechanism.In addition the oligomerization of oxidized aromatic pollutants by radicalforming extracellular fungal enzymes and various dehalogenationmechanisms (e.g. oxidative and reductive dehalogenation, dehalogenationduring cycloisomerization of ring cleavage products, and dehalogenation byoligomerization) can all lead to a progressive detoxification of persistentenvironmental pollutants.Thus, fungi possess many bio-degradative options in addition to thoseavailable to bacteria and hence the combination of all microbialdetoxification mechanisms can contribute to clearing toxic environmentalpollutants.EMP041Environmental dissemination and accumulation ofantibiotics, human pathogens and spread of antibioticresistance genes in wastewater-irrigated soils in theM. Broszat* 1 , P. Dalkmann 2 , T. Sakinc 1 , D. Wobser 1 , P. Graumann 3 ,J. Hübner 1 , J. Siemens 2 , E. Grohmann 11 Division of Infectious Diseases, Albert-Ludwig-University, Freiburg,Germany2 Institute of Crop Science and Resource Conservation, Friedrich-Westphalian Wilhelms-University, Bonn, Germany3 Faculty for Biology, Department of Microbiology, Albert-Ludwig-University, Freiburg, GermanyWastewater reuse for irrigation is a widely used practice to alleviate watershortages. Antibiotics, pathogens and resistance determinants that arereleased in the environment by wastewater irrigation pose a potential risk tospektrum | Tagungsband 2011