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

73Similar fragments develop on initially clean and sterile in situ microcosmsduring exposure in groundwater providing clear evidence for theirmicrobial origin. Microbial cell envelope fragments thus contributesignificantly to SOM formation. The results provide a simple explanationfor the development of the small, nano-scale patchy organic materialsobserved in soil electron micrographs. They suggest that microstructuresof microbial cells and of small plant debris provide the moleculararchitecture of SOM adsorbed to particle surfaces. This origin andmacromolecular architecture of SOM is consistent with most observationson SOM, e.g. the abundance of microbial-derived biomarkers, the low C/Nratio, the water repellency and the stabilisation of microbial biomass [6].The specific molecular architecture determines carbon mineralisation andbalances as well as the fate of pesticides and environmental contaminants.These conclusions were confirmed by studies [7,8] on the biodegradationof isotope labeled 2,4-D and ibuprofen in soil which quantified thecontribution of microbial residues to the NER in soil. The amount of labelfound in biomolecules indicated that virtually all of the NER of thecompounds are derived from microbial biomass.Miltner, A., Richnow, H.H., Kopinke, F.-D. and M. Kästner. Assimilation of CO2 by soil microorganismsand transformation into soil organic matter. Organic Geochemistry, 35 (2004), p. 1015 - 1024.Kindler, R., Miltner, A., Richnow, H.H. and M. Kästner. Fate of gram-negative bacterial biomass in soils -survival of cells, carbon balance and persistence of the lux gene as genetic label. Soil Biology andBiochemistry, 38 (2006), p. 2860-2870.Lueders, T., Kindler, R., Miltner, A., Friedrich, M.W. and M. Kaestner. Bacterial micropredators and fungidistinctively active in a soil food web. Applied and Environmental Microbiology, 72 (2006), p. 5342-5348.Kindler. R., Miltner, A., Richnow, H.H. and M. Kästner. Fate of microbial biomass compounds (fatty acids)in soil and their contribution to soil organic matter. Organic Geochemistry, 40 (2009), p. 29-37.Miltner, A., Kindler. R., Richnow, H.H. and M. Kästner. Fate of microbial biomass-derived amino acids insoil and their contribution to soil organic matter. Organic Geochemistry, 40 (2009) p. 978-985.Miltner A., Bombach P., Schmidt-Brücken B. and M. Kästner. SOM genesis - Microbial biomass asignificant source. Biogeochemistry, in revision.Nowak, K., Miltner, A., Gehre, M., Schäffer, A. and M. Kästner. Formation and Fate of “Bound” Residuesfrom Microbial Biomass during Biodegradation of 2,4-D in Soil. Environ. Sci. Technol, 45 (2011), p. 1127-1132.Nowak, K.M., Girardi, C., Miltner, A., Gehre, M., Schäffer, A., Kästner, M. (2011). Formation and fate ofbiogenic “non-extractable” residues during the biodegradation of 13C6-ibuprofen in soil. EnvironmentalPollution, submitted.Acknowledgement- This study was financially supported by the Helmholtz Centre for EnvironmentalResearch UFZ, by the German Research Council (DFG, Kä 887/1) and by the European Commission(ModelPROBE, contract number 213161).EMV5-FGWhat keeps microorganisms from eating emergingcontaminants? - A study on the corrosion inhibitorbenzotriazoleB. Morasch*, S.B. HaderleinUniversity of Tuebingen, Center for Applied Geoscience (ZAG),Tuebingen, GermanyNumerous anthropogenic contaminants are continuously released intofreshwater systems where they are typically present in the g/L range orbelow. These emerging contaminants might be seen as one of the mostwidespread environmental problems we are facing today. The corrosioninhibitor benzotriazole (BT) is a high production volume chemical withmany industrial and domestic applications which is almost ubiquitouslypresent in the aquatic environment. Although sharing structural similaritieswith certain biomolecules, neither in sewage sludge nor in oligotrophicfreshwater systems microorganisms seem to efficiently degrade BT. Forthe first time, an aerobic culture could be enriched and maintained thatcouples biodegradation of BT with growth. Using the enrichment culture,the biodegradation of BT was studied in further detail and inhibitoryeffects of BT on the degradation of other carbon sources were observed.BT affected biodegradation of other compounds when present atconcentrations as low as 20 mg/L. N-methylaniline could be identified as atransformation product of BT based on GC-MS analysis. Althoughreported to have toxic effects towards microorganisms, N-methylanilinewas a less efficient inhibitor of substrate utilization than BT. Ourhypothesis is that not the damage to cellular structures or the inhibition ofcell functioning in general is responsible for the inhibitory effect of BT butthat the compound acts on specific enzymes. In the context of sustainablewater quality it is important to come to a better understanding of theinhibitory influence of BT and other emerging contaminants on microbialactivities in the environment.EMV6-FGPhenoxyacetic acids - what soil microbes can handle etherlinkagesin soil?Y. Liu 1,2 , S.-J. Liu 2 , H.L. Drake 1 , M. Horn* 11 University of Bayreuth, Ecological Microbiology, Bayreuth, Germany2 Chinese Academy of Sciences, State Key Laboratory of MicrobialResources, Institute of Microbiology, Beijing, China4-Chloro-2-methyl-phenoxyacetic acid (MCPA) is one of the best sellingherbicides utilized for wheat and lawn control world wide. MCPA ischaracterized by an ether-bond between a substituted phenol and an aceticacid residue, and subject to aerobic microbial degradation in soil. Previousfindings indicated that Beta- and Gammaproteobacteria are associatedwith MCPA degradation in soils. Degradation is initiated by oxygenasecatalyzedcleavage of a glyoxylate residue. Thus, degradation occurs inaerated surface soil and macropores generated by earthworms (i.e., burrowwalls). To resolve active MCPA degraders and mine for new oxygenaseencoding genes associated with MCPA degradation in bulk and earthwormaffected soil, 16S rRNA stable isotope probing (SIP) coupled to structuralgene DNA SIP and quantitative PCR was performed. Soil columns weresupplemented with [U 13 C]-MCPA at application level concentrations (i.e.,20 g MCPA g DW -1 ) in the presence of earthworms. [U 12 C]-MCPAtreatments served as controls. MCPA was degraded within 27 days ofincubation. Total 16S rRNA analysis revealed 90 active family-level taxa,33 of which were not affiliated with known families, indicatingphylogenetic novelty in bulk soil and drilosphere. 21 and 19 major activetaxa occurred in the drilosphere and bulk soil, respectively. 12 of thosetaxa assimilated MCPA-13C and were affiliated with Alpha-, Beta-,Gammaproteobacteria, Actinobacteria, and Firmicutes.Sphingomonadaceae and Bradyrhizobiaceae of the Alphaproteobacteriadominated MCPA-assimilating bacteria, indicating that those taxa weremajor MCPA degraders bulk and earthworm affected soil. In oxicmicrocosms of bulk soil and burrow wall material supplemented with highconcentrations of [U- 13 C] MCPA (300 g g DW -1 ), Sphingomonadaceaerelatedtaxa dominated MCPA consumers, while Betaproteobacteria(Burkholderiaceae-, Comamonadaceae-, and Oxalobacteraceae-relatedtaxa) dominated MCPA consumers in cast microcosms. Structural geneSIP in such microcosms indicated that MCPA degraders host tfdA-like,cadA and r/sdpA encoding oxygenase genes. Based on 84% proteinsequence identity, 49, 6, and 17 operational taxonomic units (OTUs) ofwere detected in total, including many hitherto unknown genes. Most ofthe detected genes affiliated with oxygenase genes fromAlphaproteobacteria. 8, 6, and 4 OTUs of tfdA-like, cadA and r/sdpAgenes, respectively, were MCPA-[ 13 C] labeled. Quantitative PCR (qPCR)revealed that copy numbers of such oxygenase genes increased duringMCPA degradation in soil microcosms, and the expression of tfdA-like andr/sdpA genes was stimulated by MCPA, indicating that diverse oxygenaseencodinggenes were involved in MCPA degradation. The combined dataindicate that (i) Alphaproteobacteria rather than Betaproteobacteria aremajor MCPA degrades in certain soils and (ii) new oxygenases areassociated with MCPA degradation.EMV7-FGA new function for an old yellow enzyme: dearomatizingnaphthoyl-CoA reductase, a key enzyme in anaerobicnaphthalene degradationC. Eberlein* 1 , H. Mouttaki 2 , R. Meckenstock 2 , M. Boll 11 University of Leipzig, Institute of Biochemistry, Leipzig, Germany2 Helmholtz Center Munich, German Research Center for EnvironmentalHealth, Institute of Groundwater Ecology, Munich, GermanyPolyaromatic hydrocarbons (PAH) are harmful to the environment andhuman health; they are highly persistent due to the high resonance energyof the ring system and to the low bioavailability. Only little is known aboutenzymes involved in the anaerobic metabolism of PAHs. The initialactivation of naphthalene is considered to proceed by carboxylationyielding 2-naphthoic acid 1,2 , which is then activated to 2-naphthoyl-CoAby a specific ligase. Initial evidence was obtained that this keyintermediate is dearomatized by reduction 3,4 . Using extracts from thesulphate reducing, naphthalene degrading enrichment culture N47 thetime-, protein- and electron donor dependent reduction of 5,6,7,8-tetrahydronaphthoyl-CoA (THNCoA) was demonstrated. This activity (5.1± 1.2 nmol min -1 mg -1 ) was sufficiently high for the growth rate of cells;surprisingly it was not oxygen sensitive and not dependent on ATPhydrolysis. Protein purification/characterization including massspectrometric analysis of tryptic digests revealed that the 2-naphthoyl-CoAreductase (NCR) is a member of the old yellow enzyme (OYE)-family.UV/vis spectra supported the existence of a flavin cofactor and FeSclusters.The newly identified enzyme represents the prototype of a novelclass of aryl-CoA reductases.1 Musat 2009 Env Microbiol 11:209-192 Bergmann 2011 Arch Microbiol 4:241-2503 Annweiler 2002 Appl Env Microbiol 68:852-858.4 Selesi 2010 J Bac 192:295-306EMP1-FGChallenging Microbial Infallibility: Investigations on theBiodegradability of Cyclic PeptidesM. Perzborn*, C. Syldatk, J. RudatKarlsruhe Institute of Technology, IBLT, Section II: Technical Biology,Karlsruhe, GermanyDiketopiperazines (DKPs) are the smallest possible cyclic peptidescomposed of two -amino acids. They are abundant natural compoundsproduced by a variety of microorganisms as secondary metabolites, e.g. asquorum sensing molecules [1]. Moreover DKPs occur as degradationproducts e.g. of aminopenicillin antibiotics [2] which are under discussionBIOspektrum | Tagungsband 2012