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

74as health problem due to the allergenic potential of these exceptional stablecompounds.Although their abundance in nature, little is known about thebiodegradation of this substance class and only for few strains hydrolysisof DKPs is reported. In this study we present different approaches toidentify potential DKP degrading strains and enzymes, testing eight DKPssynthesized from proteinogenic amino acids and three from nonproteinogenicamino acids (e.g. sarcosine) as substrates:- Despite peptidase activity against some DKPs has been reported sometime ago [3] tested activities could not be confirmed in our lab. Furtherexperiments with additional peptidases indicate peptidase stability for allused DKPs.- Recently certain cyclic amidases (hydantoinases) have been shown toalso cleave dihydropyrimidine derivatives which are structurally related toDKPs [4]. We could demonstrate degradation of different DKPs by threestrains exhibiting such cyclic amidase activity. Whether the responsibleenzymes are the same is subject of further investigations.- Paenibacillus chibensis (DSM 329) and Streptomyces flavovirens (DSM40062) have been described to hydrolyze the aspartame derivativecyclo(L-Asp-L-Phe) [5]. In our studies this activity appeared to besubstrate inducible in S. flavovirens but not in P. chibensis. Moreover wedetected the degradation of an additional substrate cyclo(L-Asp-L-Asp) byP. chibensis while no other of the tested DKPs was hydrolyzed by one ofthese strains.- Two bacterial strains isolated during this study were shown toenantioselectively cleave racemic cyclo(DL-Ala-DL-Ala). We coulddemonstrate that the cyclo(D-Ala-D-Ala) isomer was not attacked by bothstrains which were identified as Microbacterium sp. and Paenibacillus sp.by 16S rDNA sequence analysis.1. M.B. Martins, I. Carvalho, Tetrahedron63(2007), p. 9923.2. A. Lamm, I. Gozlan, A. Rotstein, D. Avisar, J Env Sci Health Part A44(2009), p. 1512.3. T. Ishiyama, J Biochem17(1933), p. 287.4. U. Engel, C. Syldatk, J. Rudat, Appl Microbiol Biotechnol, published online Nov 27th, 2011.5. EP 0 220 028 - B1 (1990) AJINOMOTO CO.EMP2-FGEthylbenzene - Isotope fractionation measurements as a tool tocharacterize aerobic and anaerobic biodegradationC. Dorer* 1 , A.J.M. Stams 2 , H.H. Richnow 1 , C. Vogt 11 Helmholtz Centre for Environmental Research - UFZ, Department ofIsotope Biogeochemistry, Leipzig, Germany2 Wageningen University, Laboratory of Microbiology, Wageningen,NetherlandsBTEX compounds (benzene, toluene, ethylbenzene and xylenes) arecommon pollutants in our environment released from spillings of gasoline.As hydrocarbons are chemically inert compounds they need to be activatedto start degradation processes. For long time only molecular oxygen ashighly reactive cosubstrate was known to initiate biological decompositionof these compounds. In the last years biochemically completely differentmechanisms for initial attack under anoxic conditions were elucidated.Two of them are relevant for ethylbenzene degradation: fumarate additionand oxygen-independent hydroxylation. The better we know whichbiodegradation process prevails the better it is possible to make reliablepredictions for remediation measures.Here we present isotope fractionation measurements of carbon andhydrogen as a tool to characterize the biodegradation processes ofethylbenzene and a cheap means for monitoring the transformation atcontaminated sites. Different reaction mechanisms are reflected bydifferent isotope effects (the result of different reaction rates of moleculescontaining the light or the heavy isotope). By this way the initial step ofvarious degradation pathways can be differed by determining the singleand combined fractionation behaviour of carbon and hydrogen.Investigated ethylbenzene dehydrogenase catalysed reactions by nitratereducingtest organisms (Aromatoleum aromaticum, Georgfuchsiatoluolica and Azoarcus sp.) show a pronounced hydrogen fractionationcontrasting to aerobic transformation via hydroxylation of the side-chain orthe ring (investigated for Pseudomonas putida and an enrichment culturedominated by an Acidovorax-related species, respecively. Furthermoremasking effects can be excluded by looking at two elements at the sametime.Altogether the newly gained isotopic enrichment factors from various labcultures will be useful for application at field sites and will complete thepicture of isotope effects for BTEX compounds.EMP3-FGChloroethenes in a historical context: From recalcitrance tocomplete mineralizationS. Mungenast*, I. Kranzioch, I. Kranzioch, K.R. Schmidt, A. TiehmDVGW-Water Technology Center (TZW), Department of EnvironmentalBiotechnology, Karlsruhe, GermanyChloroethenes were identified as common contaminants in groundwater asearly as the 1970s (1). Their extensive use as degreasing or dry cleaningsolvents and synthetic feed stocks until today has led to groundwatercontamination world wide. They are included in the USEPA’s list ofprimary regulated drinking water contaminants (2), because of their toxicand carcinogenic effects on human health.Common consensus until 1980 was that chlorinated ethenes(Tetrachloroethene (=Perchloroethene, PCE); Trichloroethene (TCE); thethree dichloroethenes isomers (cDCE, tDCE, 1,1DCE) and vinyl chloride(VC)) were recalcitrant to biodegradation. This opinion was supported bythe fact that these compounds were thought to be only of anthropogenicorigin. In addition to that only little importance was assigned to biologicalprocesses in groundwater before the 1980s (1).After several studies on the fate of PCE and TCE in anaerobicgroundwater and the accumulation of cDCE or VC as possibletransformation products, it was clear at the end of the 1980s that microbialreductive dechlorination can take place in anaerobic, chloroethenecontaminated aquifers. From that time on researchers all over the worldaddressed biological degradation of chloroethenes under different redoxconditionsand with a wide range of auxiliary substrates. Today thecommon opinion is that chloroethenes with higher chlorine content (PCE,TCE) can be degraded more easily under anaerobic conditions serving aselectron acceptors and chloroethenes with lower chlorine content (DCE,VC) can be degraded more easily under aerobic conditions serving aselectron donors (3).Here we want to report recent findings on reductive dechlorination, onaerobic metabolism (cometabolic and productive) of lower chlorinatedethenes and on first results indicating that aerobic productivebiodegradation of TCE is possible.(1) P. M. Bradley, Bioremediation Journal72003, p. 81.(2) Code of Federal Regulations Title 40, Pt.141.50 (2002 ed).(3) A. Tiehm and K. R. Schmidt, Current Opinion in Biotechnology22(2011), p. 415.(4) The authors kindly acknowledge financial support by BMWi (AiF project no. 16224 N).EMP4-FGSoil microbial communities involved in carbon cycling duringleaf litter degradation of annual and perennial plantsS. Wallisch* 1,2 , W. Heller 3 , S. Stich 3 , F. Fleischmann 4 , M. Schloter 2,51 Helmholtz Zentrum München, environmental genomics, Oberschleissheim,Germany2 Technische Universitaet Muenchen, Chair of Soil Ecology, Neuherberg,Germany3 HelmholtzZentrum Muenchen – German Research Center for EnvironmentalHealth, Institute of Biochemical Plant Pathology, Research Group of PlantAbiotic Stress, Neuherberg, Germany4 Technische Universität München, Phytopathology of Woody Plants,Freising, Germany5 HelmholtzZentrum Muenchen, Research Unit Environmental Genomics,Neuherberg, GermanyMicrobial degradation of plant litter materials provides the primaryresources for organic matter formation in soil. The aim of this study was toenlighten the role of bacterial colonisation on leaf litter fragments and toinvestigate shifts in microbial diversity during leaf litter degradation in thecontext of carbon cycling.Therefore, we compared two different litter types: (I)Zea maysas annualand (II)Fagus sylvaticaas perennial model plant. Leafs were sewed intonylon bags and incubated for up to eight (Z. mays) and thirty (F. sylvatica)weeks, respectively, in the soil. The state of degradation was determinedby the loss of dry weight. For molecular analyses 16S rRNA genes weredetected by two different fingerprinting techniques, terminal restrictionfragment length polymorphism (T-RFLP) and enterobacterial repetitiveintergenic consensus sequences (ERIC). To get a deeper insight whichbacterial communities are involved in litter degradation next generationsequencing using a 454 platform was performed. Additionally, the amountof sugars, amino sugars and phenols was analysed.First results of the experiment with litter of the annual plant showed aconsistent pattern of microbial community shifts. T-RFLP, ERIC andsequencing results reflected concordantly changes of the bacterialcommunity over time. Summarizing, microbial diversity increased duringleaf litter degradation and bacterial strains related to carbon cycling suchasActinomycetesandMyxococcalescould be identified. Further analyseswill reveal how microbial diversity develops on perennial leaf litter.Different results are expected as the litter ofF. sylvaticacontains higheramounts of persistent substances as lignin and celluloses compared toZeamays.EMP5-FGBenzotriazole derivatives: biodegradation patterns with threedifferent activated sludge biocenosesB. Herzog* 1 , H. Lemmer 2 , H. Horn 1 and E. Müller 11 Institute of Water Quality Control, TU München, Garching, Germany2 Bavarian Environment Agency, Munich, GermanyThe compounds benzotriazole (BT), 5-methylbenzotriazole (5-TTri) and 4-methylbenzotriazole (4-TTri) are polar micropollutants widely used asBIOspektrum | Tagungsband 2012