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

223SMP040amoA-based consensus phylogeny of ammonia-oxidizingarchaea and deep sequencing of amoA genes from soils of fourdifferent geographic regionsM. Pester* 1 , T. Rattei 2 , S. Flechl 1 , A. Gröngröft 3 , A. Richter 4 , J. Overmann 5 ,B. Reinhold-Hurek 6 , A. Loy 1 , M. Wagner 11 University of Vienna, Department of Microbial Ecology, Vienna, Austria2 University of Vienna, Department of Computational Systems Biology, Vienna,Austria3 University of Hamburg, Institute of Soil Science, Hamburg, Germany4 University of Vienna, Department of Chemical Ecology and EcosystemResearch, Vienna, Austria5 Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen undZellkulturen, Braunschweig, Germany6 University of Bremen, Department of Microbe-Plant Interactions, Bremen,GermanyAmmonia-oxidizing archaea (AOA) play an important role in nitrificationand many studies exploit their amoA genes as marker for their diversityand abundance. We present an archaeal amoA consensus phylogeny basedon all publicly available sequences (status June 2010) and provideevidence for the diversification of AOA into four previously recognizedclusters and one newly identified major cluster. These clusters, for whichwe suggest a new nomenclature, harbored 83 AOA species-level OTUs(using an inferred species threshold of 85% amoA identity). 454pyrosequencing of amoA amplicons from 16 soils sampled in Austria,Costa Rica, Greenland, and Namibia revealed that only 2% of retrievedsequences had no database representative on the species-level andrepresented 30-37 additional species-level OTUs. With the exception of anacidic soil from which mostly amoA amplicons of the Nitrosotalea clusterwere retrieved, all soils were dominated by amoA amplicons from theNitrososphaera cluster (also called group I.1b), indicating that thepreviously reported AOA from the Nitrosopumilus cluster (also calledgroup I.1a) are absent or represent minor populations in soils. AOArichness estimates on the species level ranged from 8-83 co-existing AOAsper soil. Presence/absence of amoA OTUs (97% identity level) correlatedwith geographic location, indicating that besides contemporaryenvironmental conditions also dispersal limitation across differentcontinents and/or historical environmental conditions might influenceAOA biogeography in soils.SMP041Organic propagation of olive nursery plants using Pantoeaeucrina strain AG9M.D.C. Montero-Calasanz* 1,2 , C. Santamaría 2 , A. Daza 2 , E. Lang 1 , H.-P. Klenk 1 , M. Camacho 21 Leibniz Institute DSMZ- Deutsche Sammlung von Mikroorganism undZellKulturen GmbH , Department of Microbiology, Braunschweig, Germany2 IFAPA Centro Las Torres-Tomejil. Junta de Andalucia., Department ofNatural Resources and Organic Production, Alcala del Rio (Sevilla). SPAIN.,SpainThe demand for organic olive oil is increasing exponentially each year(MARM, 2010). However, nowadays there is not a commercial methodthat can replace the use of a synthetic hormone in organic propagation ofolive nursery plants.The goal of this work is the development of an organic olive propagationmethod based on the use of the strain AG9 (Pantoea eucrina), previouslycharacterized as a Plant Growth Promoting Rhizobacteria (PGPR). Thisstrain has been used in monoxenic model systems showing both, higherrooting induction and root elongation than negative controls, in mung beanand canola assays. Moreover, this bacterium has been tested in four olivecultivars, under nursery conditions, displaying higher or similareffectiveness than the hormonal treatments. These results underwrite theworth of this method.On the other hand, by means of Confocal Laser Scanning Microscope(CLSM) and GFP tagged bacterial cells, it was confirmed that this strain isable to colonize the plant roots permanently as an endophyte and topromote the plant growth a long-term.MARM. Anuario de Estadística. Ministerio de Medio Ambiente, MedioRural y Marino. Gorbierno de Espana (2010).SMP042Temperature effects of geothermal energy use on themicrobial community in subsurface environmentsF. Hegler* 1 , T. Lüders 1 , G. Bisch 2 , P. Blum 3 , C. Griebler 11 Helmholtz Zentrum München, Institute of Groundwater Ecology, Neuherberg,Germany2 University of Stuttgart, VEGAS - Institut für Wasser- undUmweltsystemmodellierung, Stuttgart, Germany3 Karlsruhe Institute of Technology (KIT), Institute for Applied Geosciences,Karlsruhe, GermanyGeothermal energy use has boomed in the last years. In winter, theexploitation of geothermal energy can be used to heat buildings and insummer to cool them. Especially geothermal heat exchangers up to 100 mdepth are installed frequently. Although geothermal energy use is acceptedas being environmentally friendly, several aspects need to be considered inan evaluation of its use. While complications during drilling (e.g. leadingto cracks in houses) or during the operation of geothermal heat systems(e.g. leakage of anti-freezing agents to the aquifer) are caused bymisjudgment or accidents, other effects cannot be avoided.Generally, temperature in the subsurface deeper than 15 m is constant overthe year. Geothermal heat exchangers may decrease or increase thetemperature locally. Therefore, in our study we focus on the effects oftemperature changes on the subsurface environment adjacent togeothermal heat exchangers. Temperature shifts influence the viscosity anddensity of water but also the solubility of liquids, solids, gases andgenerally the geochemical equilibrium. Not only may geochemicalequilibria shift but also the microbial communities and fauna may beinfluenced by temperature. While temperature effects on the microbialcommunity for open, nearer surface geothermal systems are documented[1,2] the current project aims to evaluate possible shifts induced bygeothermal heat exchangers.With this study we are presenting first results for the effect of changingtemperatures on the microbial community in a usually constanttemperature environment such as the subsurface.1. Brielmann, H., et al., Oberflächennahe Geothermie und ihre potentiellen Auswirkungen aufGrundwasserökologie. Grundwasser, 2011.16: p. 77-91.2. Brielmann, H., et al., Effects of thermal energy discharge on shallow groundwater ecosystems.FEMS Microbiology Ecology, 2009.68: p. 273-286.SMP043Microbial carbon decomposition under anoxic conditions inpermafrost-affected soil of the Qinghai-Xizang PlateauS. Yang*, D. WagnerAlfred Wegener Institute for Polar and Marine Research,Geomicrobiology, Potsdam, GermanyThe Qinghai-Xizang Plateau (QXP) in high Asia is the third permafrostunit outside polar regions, about 54.3% of it is covered by permafrost,retaining 23% SOM of Chinese soils or 2.5% of the global pool (Wang etal., 2002). Affected by India and Asian monsoon, the plateau differs intemperature and moisture gradients along the monsoon routes, making thefate of SOM within QXP soil more complicated. The SOM turnover ismainly driven by microbial communities which decompose permafrostSOM via a sequence of microbial processes to CH 4 under anaerobicconditions (methanogenesis), which is a rather strong greenhouse gas. Inresponse to climate warming, QXP permafrost degradation has beenenhanced over the past decades, the methane turnover via methanogens istherefore our focus from the view of global change research. Aninterdisciplinary project is conducted along the two different monsoongradients to link thein-situ methane flux with temporal and spatialvariations of permafrost soil carbon (e.g. ST, SM, SRP, SOMs, TOC, pH)and dynamics of methanogenic consortia. Attention will be paid on theanaerobic carbon decomposition, dynamics of archaeal communities andtheir reaction to global change by using methane producing rate analysisand a diverse molecular biotechniques including DGGE and t-RFLPfingerprints, cloning, FISH and real-time PCR to quantitatively andqualitatively investigate the diversity, abundance and the changes of thecomposition of archaeal communities. On this basis, it is expected to beable to improve our understanding about the potential anoxicdecomposition of permafrost SOMs under different the climate gradientsand its future development under global warming.Wang G.X., Ju Q., Cheng G.D., and Lai Y.M.. 2002. Soil organic carbon pool of grassland soils onthe Qinghai-Tibetan Plateau and its global implication. Science of The Total Environment,291(1-3):207-217.BIOspektrum | Tagungsband 2012