VAAM-Jahrestagung 2012 18.–21. März in Tübingen

172where lowest concentrations were recorded. Methane oxidation ratesmostly followed this pattern. Experiments simulating the mixing offreshwater methanotrophic bacteria from the river with the saline waters ofthe Laptev Sea indicate that at salinities above 5 PSU their function asbiofilter ends.OTP158Inhibition of the anaerobic degradation of ethylene glycol bybenzotriazolesD. Ilieva*, B. Morasch, S. HaderleinUniversity of Tübingen, Center for Applied Geoscience (ZAG),Environmental Mineralogy & Chemistry, Tübingen, Germany1H-benzotriazole and its methylated derivative tolyltriazole belong to themost frequently used corrosion inhibitors in borehole heat exchangersystems.In case of a leakage, a local groundwater contamination mightoccur where ethylene glycol-based heat transfer fluid containing corrosioninhibitors enter the aquifer down to a depth of 150 meters. Microcosmexperiments with sediment inoculum showed that the two corrosioninhibitors are resistant to biodegradation under sulfate-, nitrate- and ironreducingconditions. This study describes the inhibitory effect ofbenzotriazoles on ethylene glycol degradation under nitrate- and sulfatereducingconditions.Experiments were conducted using a sediment inoculum from a depth of60 meters, which was sampled during the installation of a borehole heatexchanger system. The biodegradation of ethylene glycol (5 mM) wasassessed as the sole carbon source and in the presence of (50 M) of eachof the benzotriazoles. Microcosm experiments were performed in triplicateat 12°C and room temperature (RT).In the absence of benzotriazoles more than 98 % of the initial ethyleneglycol was degraded within eight days by the denitrifying bacteria. In thepresence of the two corrosion inhibitors the degradation of ethylene glycolproceeded at a lower rate and 98 % of the substrate were not degradeduntil 15 days of incubation. Under sulfate-reducing conditions 50-100% ofthe initial ethylene glycol concentration was utilized within 138 days ofincubation in the absence of benzotriazoles. The presence of 1H-Benzotriazole caused inhibition of the biodegradation of ethylene glycol atlower temperatures. In the presence of tolyltriazole the effect on theethylene glycol degradation was variable, which might be explained by theheterogeneous distribution of microorganisms in the inoculum.These findings indicate that benzotriazoles may not only threatengroundwater quality due to their own toxicities but in addition inhibit thebiodegradation of other organic compounds.PSV001The unusual cell architecture of I. hospitalis and consequencesfor its energy metabolismL. Kreuter* 1 , S. Daxer 1 , U. Küper 1 , F. Mayer 2 , V. Müller 2 , R. Rachel 3 ,H. Huber 11 Universität Regensburg, Lehrstuhl für Mikrobiologie, Regensburg, Germany2 Goethe-Universität, Institut für Molekulare Biowissenschaften, Frankfurt/Main, Germany3 Universiät Regensburg, Zentrum für Elektronenmikroskopie der Fakultät fürBiologie und Vorklinische Medizin, Regensburg, GermanyThe members of the genus Ignicoccus belong to the phylum of theCrenarchaeota. They obtain energy chemolithoautotrophically by thereduction of elemental sulfur with molecular hydrogen as electron donor(1). All described Ignicoccus species exhibit a unique cell architecture thatdiffers from all other Archaea known so far. The cell envelope consists oftwo membranes enclosing a huge inter-membrane compartment (IMC).Surprisingly, it was shown for I. hospitalis that the outermost membranecontains the H 2:sulphur oxidoreductase as well as the ATP synthase. Thus,I. hospitalis is the first organism with an energized outermost membraneand ATP synthesis within the IMC. DAPI staining and EM analysesshowed that DNA and ribosomes are localized in the cytoplasm, leading tothe conclusion that energy conservation is separated from informationprocessing and protein biosynthesis (2). In addition, we were able todemonstrate that the acetyl-CoA synthetase that activates acetate to acetyl-CoA is associated to the outermost membrane. This is the first energyconsumingprocess proven to take place in the inter-membranecompartment.To further investigate the energy metabolism under these extraordinaryconditions, we are working on the purification and characterization of thecomplete ATP synthase complex of I. hospitalis. This includes studies onthe stability of the enzyme complex, its molecular composition, and itsbehaviour against inhibitors. The findings of these experiments also willshed light on the nature of the intimate association between I. hospitalisand Nanoarchaeum equitans (3). It is known that N. equitans receivesamino acids and lipids from its host. At present, it is still unclear if theenergy metabolism of N. equitans is dependent on I. hospitalis, too.Finally, a re-examination of the nomenclature of the differentcompartments and the two membranes of I. hospitalis will be discussed.(1) Paper W. et al. 2007 Int. J. Syst. Evol. Microbiol. 57:803-808(2) Kueper U. et al. 2010 PNAS 107: 3152-3156(3) Jahn U. et al. 2008 J. Bacteriol. 190: 1743-1750(4) This project is supported by a grant from the DFGPSV002Function and specificity of the dual flagellar sytem inShewanella putrefaciens CN-32S. Bubendorfer* 1 , S. Held 1 , N. Windel 1 , A. Paulick 1 , A. Klingl 2 , K. Thormann 11 Max-Planck-Institut für terrestrische Mikrobiologie, Ecophysiology, Marburg,Germany2 Philipps-Universität Marburg, Cell Biology, Marburg, GermanyBacteria move towards favorable conditions by rotating helicalproteinaceous filaments, called flagella. The motor part of this intricatebacterial nanomachine incorporates stator units that exert torque on thefilament using gradients of H + - or Na + -ions. Stator units and the rotorcomponent FliM can be dynamically exchanged during function. Previousstudies have shown that a large number of microorganisms harbor dualflagellar systems. However, little is known about function and regulationof dual flagellar systems in many species.The -proteobacterium Shewanella putrefaciens CN-32 possesses acomplete secondary flagellar system along with a corresponding statorunit. In contrast to most secondary flagellar systems that have been studiedso far, expression already occurs during planktonic growth in complexmedia and leads to the formation of a subpopulation with one or moreadditional flagella at random positions in addition to the primary polarsystem. We used physiological and phenotypic characterizations of definedmutants in concert with fluorescent microscopy on labeled components ofthe two different systems, the stator proteins PomB and MotB, the rotorcomponents FliM 1 and FliM 2,and the auxiliary motor components MotXand MotY, to determine localization and function of the proteins in theflagellar motors.Our results demonstrate that the polar flagellum is driven by a Na + -dependent FliM 1/PomAB/MotX/MotY flagellar motor, while thesecondary motor is rotated by a H + -dependent FliM 2/MotAB motor. Thereis strong evidence that these components are highly specific for theircorresponding motor and are unlikely to be extensively swapped or sharedbetween the two flagellar systems under planktonic conditions. The resultshave implications for the specificity and dynamics of flagellar motorcomponents.PSV003Pyruvate formate-lyase Controls Formate Translocation bythe FocA ChannelC. Doberenz* 1 , L. Beyer 1 , D. Falke 1 , M. Zorn 2 , B. Thiemer 1 , G. Sawers 11 Martin-Luther-University Halle, Biology/Microbiology AG Sawers, Halle,Germany2 Martin-Luther-University Halle, Pharmacy AG Sinz, Halle, GermanyFormate is one of the major products of mixed-acid fermentation inEnterobacteria such as Escherichia coli and is an important electron donorfor many anaerobes. During fermentation in E. coli up to one third of thecarbon derived from glucose is metabolized to formate. The final step iscatalyzed by the cytoplasmic enzyme pyruvate formate-lyase (PflB), whichcatalyses the homolytic cleavage of pyruvate to acetyl-CoA and formate.PflB is a glycyl-radical enzyme that is converted from an inactive to anactive form by the radical-SAM enzyme PflA 1 .Because accumulation of formate inside the cell can lead to acidification ofthe cytoplasm a mechanism to regulate its intracellular level must exist.FocA is a bidirectional formate channel protein that belongs to the familyof formate-nitrite transporters (FNT) 2 . Its gene, focA, is co-transcribed withthat encoding PflB. Although several structures of FocA have beenpublished recently 3 , there is still no clear mechanistic understanding ofhow formate import and export by FocA is controlled. Because synthesisof FocA and PflB is highly coordinated this suggested that PflB might playa key role in controlling formate translocation across the cytoplasmicmembrane. In initial experiments we could show a FocA-dependentinteraction of PflB with the cytoplasmic membrane. The specificity of theFocA-PflB interaction could be subsequently confirmed using a variety ofin vivo and in vitro experimental approaches. Our findings indicate that itis the inactive form of PflB that interacts with FocA. Based on thesefindings we developed an assay to test our model for PflB-controlledgating of formate transport by FocA in vivo.1 Sawers RG & Clark DP (2004) Fermentative pyruvate and acetyl CoA metabolism. Chapter 3.5.3. EcoSal -Escherichia coli and Salmonella: Cellular and Molecular Biology (Curtiss R III, (Editor in Chief) ASMPress, Washington, DC.2 Suppmann B & Sawers G (1994) Isolation and characterization of hypophosphite-resistant mutants ofEscherichia coli: identification of the FocA protein, encoded by the pfl operon, as a putative formatetransporter. Mol Microbiol 11: 965-982.3 Wang et al., (2009) Structure of the formate transporter FocA reveals a pentameric aquaporin-like channel.Nature vol. 462 (7272) pp. 467-472;Waight et al., (2010) Structure and mechanism of a pentameric formate channel. Nat Struct Mol Biol 17, 31-37.;Lü et al., (2011) pH-Dependent Gating in a FocA Formate Channel. Science vol. 332 (6027) pp. 352-354BIOspektrum | Tagungsband 2012