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

Results: The change from heterotrophic growth in the dark tophotoheterotrophic growth in the light was accompanied by a strong buttransient activation of a broad stress response to cope with the formation ofharmful singlet oxygen during photophosphorylation, an immediatedownregulation of photosynthesis-related genes, fine-tuning of theexpression of electron transport chain components and upregulation of thetranscriptional and translational apparatus. Furthermore, our data indicatethat D. shibae might use the 3-hydroxypropionate cycle for CO2fixation.Analysis of the transcriptome dynamics after the switch from lightto dark demonstrates that only few genes are directly regulated in responseto light and other signals such as singlet oxygen concentration, electronflow, redox status and energy charge of the cell must be involved in theregulation of the processes accompanying AAP. This study provides the firstanalysis of AAP on the level of transcriptome dynamics. Our data allow theformulation of testable hypotheses about the mechanisms involved in theregulation of this important biological process.EMP097Fine scale depth monitoring of aerobic vs. anaerobictoluene degradation potentials over a redox gradient in acontaminated aquiferM. Larentis*, K. Hoermann, T. LuedersInstitue of Groundwater Ecology, Helmholtz Center, Munich, GermanyMicroorganisms are important driving forces for degradation of hydrocarbonpollutants in groundwater environments. However, BTEX contaminants canbe utilized as carbon and energy source under different hydrogeological andredox settings. It was previously shown that the distribution of anaerobictoluene degraders as traced via functional marker genes and that of typicaliron- and sulphate-reducing groups is highly correlated to zones of increasedanaerobic degradation at the lower fringe of an actual contaminant plume[1].Here, we proceeded in order to elucidate the respective contribution ofaerobic and anaerobic processes to net contaminant removal at the upperplume fringe, situated at an aerobic/anaerobic redox gradient. Geneticmonitoring strategies based on the fingerprinting and sequencing ofribosomal gene amplicons were applied. Well-defined small-scaledistribution patterns of typical aerobic and anaerobic degrader lineages wererevealed. Via catabolic gene-targeted qPCR, we provide first interestinginsights into pronounced quantitative configurations of aerobic andanaerobic toluene degraders over the redox gradient above the BTEX plume.An unexpected stratification of toluene oxygenase (tmoA) genes wasobserved with respect to oxygen availability. Surprisingly, this marker wasfound at maximal depth-resolved abundance in plume zones considered asabsolutely reduced, such as the plume core, and not at the plume fringe. Thismay point towards unusual ecological controls of these putative aerobiccontaminant degraders. In ongoing m-RNA analyses, we want to proveweather this localisation of presumed aerobic degraders could substantiatean importance of aerobic degradation without oxygen, as has been proposedalso for other processes of hydrocarbon turnover in anaerobic environments[2]. This knowledge may provide a powerful tool to monitor the real stateand capacity of natural attenuation and bioremediation in contaminated fieldsites.[1] Winderl et al (2008): Appl Environ Microbiol 74, 792.[2] Ettwig et al (2010): Nature 464, 543.EMP098Raman spectroscopy for the detection of molecularchanges induced in bacteria by various heavy metalsV. Ciobota* 1 , E.-M. Burkhardt 2 , P. Rösch 1 , K. Küsel 2 , J. Popp 1,31 Intitute of Physical Chemistry, Friedrich-Schiller-University, Jena,Germany2 Institute of Ecology, Friedrich-Schiller-University, Jena, Germany3 Institute of Photonic Technology, Jena, GermanyInvestigations focused on the diversity of microbial community in differentheavy metals contaminated sites indicate that Acidiphilium species are acommon presence in this type of environment [1]. To gain a betterunderstanding of the role played by these organisms in the remediationprocess and their resistance mechanisms towards different toxic metals, astudy focused on the changes induced by various heavy metals inmicroorganisms is required.For the investigation of the biochemical changes induced by various heavymetals in microorganisms, Raman spectroscopy was used. Compared withother spectroscopic approaches, the advantages of this micro-Ramanspectroscopic technique represent its non-invasive character, minimalsample preparation, and the fact that only one bacterial cell is required torecord the fingerprint Raman spectrum which provides information aboutthe chemical composition of the investigated microorganism. Variousstudies demonstrate that Raman spectroscopy in combination with differentchemometrical methods, e.g. HCA, LDA, SVM or ANN, can besuccessfully applied in bacterial identification [2; 3]. However, an importantfactor which could hinder the bacterial identification by means of Ramanspectroscopy represents the accumulation of storage materials within thecells. A number of microorganisms are known to produce various polymersas carbon and energy storage molecules. By far, the most commoncompound produced by bacteria is polyhydroxybutyrate (PHB). Since thispolymer can be accumulated in high amounts within the bacterial cells, it isexpected that the Raman signals from the above mentioned substancepartially or totally overlap the bands from others cell components.A. cryptum JF-5, a dissimilatory Fe- and Cr reducing bacterium whichproduce large amount of PHB, was investigated with respect to the influenceof chromium, copper, cadmium and nickel on the biochemical compositionof the cells. The changes induced by the heavy metals in the chemicalcompositions of the microorganisms can be correlated to the type andamount of toxic substances present in the environment. The obtained resultssuggest that various resistance strategies are used by the investigatedbacterium to adapt to the environmental conditions.Acknowledgement: We gratefully acknowledge financial support from theDeutsche Forschungsgemeinschaft (Graduiertenkolleg „Alteration andelement mobility at the microbe-mineral interface”) as well as the TMC(Microplex).[1] Dopsonet, M. al (2003): Microbiol. 149, 1959.[2] Kirschner, C. (2001) Microbiol 39, 1763.[3] Harz, M. (2009): Cytometry, 75A, 104.EMP099Sequence analysis of pxmABC, a pmoCAB homologuewith yet unknown function, from rice rhizosphere soilS. Yoon*, W. LiesackDepartment for Biogeochemistry, Max Planck Institute for TerrestrialMicrobiology, Marburg, GermanyMethanotrophs are a group of bacteria that utilize methane for energy andcarbon source. pMMO, one of the two enzymes that mediate the first step inmethane metabolism, was previously known to be encoded by pmoCAB as isits homologue, ammonia monooxygenase (encoded by amoCAB). Recently,several genome sequencing projects have identified novel pmo-like genesarranged in ABC orientation in strains of Methylomonas, Methylobacter, andMethylomicrobium. Named pxm, these genes have also been identified fromfreshwater sediment and Methylomonas methanica S1. Interestingly,sequences of these genes diverge significantly from any previously-knownPmo/Amo and their functional role remains yet elusive.To examine their evolutionary and ecological context, we have identifiedand analyzed pxmA genes in rice rhizosphere soil. Using newly developedprimer sets, a clone library was generated by nested PCR that specificallyamplified partial pxmA sequences of ~450 bp. Our pxmA sequence data werecombined with those deposited in the GenBank/EMBL database for furtheranalyses.All pxmA sequences were highly conserved with no indels despite the factthat different sets of primers and PCR techniques were applied for theacquisition of the sequences. Approximately 70 pxmA sequences wereplaced into five different clusters in a phylogenetic tree including oneentirely novel cluster with ~60% of clones grouped within, indicating thateither previous primer sets were incomprehensive or that composition ofpxmA genes in soil and aquatic environment may differ. dN/dS value forclusters ranged between 0.0192 to 0.136, strongly indicating that these pxmgenes have significant functional role. Their relatively uniform codon usagepatterns may indicate that their hosts are phylogenetically very closelyrelated and thus be confined to type Ia methanotrophs. From the sequenceinformation, we speculate that these genes may provide insight into the linkbetween methane and nitrogen metabolism and thus, we expect to extendthis work to confirm this hypothesis by investigating their functional rolefrom both biological and ecological standpoints.spektrum | Tagungsband 2011