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

exudation will influence the composition of the microbial community. Inthis study we investigated the community composition and genetic capacityof the rice rhizospheric microbial community. Therefore, rice plants (Oryzasativa) were grown in the greenhouse and rhizospheric soil samples werecollected from replicate plants at five different time points during thedifferent growth stages. Changes in the microbial community weremonitored using Bacteria- und Archaea-specific terminal restrictionfragment length polymorphism analysis (T-RFLP) of the 16S rRNA gene,followed by cloning and sequencing. The genetic potential of the soilmicrobial community was analyzed using the GeoChip microarray. GeoChipis a high throughput tool for studying microbial community structure linkingto ecosystem processes and changes, that includes 28 000 probes covering57 000 gene variants from 292 functional gene families involving carbon,nitrogen, phosphorus and sulfur cycles, energy metabolism, metal resistanceas well as methanogenesis. Using the advantage of the functional gene arrayGeoChip to investigate the structure, diversity and metabolic activity of themicrobial community and the ability of T-RFLP analysis to profile themicrobial community, we will be able to get a precise overview of theimpact of root exudation during the growth stages on the microbialcommunity located in the rhizosphere of irrigated rice plantsMDP009Extracellular bacterial chitinases from marineenvironmentsT. Staufenberger* 1 , V. Klokman 2 , A. Gärtner 3 , H. Heindl 1 , J. Wiese 3 ,A. Labes 1 , J.F. Imhoff 31 Kieler Wirkstoff-Zentrum, Kiel, Germany2 Department of Marine Sciences, UNC Chapel Hill, Chapel Hill, USA3 Leibniz Institute of Marine Sciences, Marine Microbiology, Kiel, GermanyChitin production in marine environments is enormous. Estimates for only asingle genus of zooplankton (copepods) are exceeding billions of tons peryear [2]. Due to these large amounts of chitin produced in marineenvironments, its degradation via chitinases is an extremely important stepin nutrient cycling [4]. Chitinases mainly hydrolyse the beta-1,4-glycosidicbond between the chitin subunits and are members of the glycosidehydrolase (GH) superfamily [1]. Most of the bacterial chitinases belong tothe GH 18 family [3].In this work, 145 bacterial strains from the Baltic and the Mediterraneanshallow and deep sea were investigated. The strains were screened for theirgenetic and physiological capability to degrade chitin. Within 53 strains aglycoside hydrolase family 18 A gene fragment was detected. Thephylogenetic analysis revealed a broad distribution of chitinolyticmicroorganisms in the bacterial domain of life from different marinehabitats. However, our findings show that only 17.8 % of the bacteriapossessing the GH18 A gene fragment were able to degrade untreated chitin.Degradation of chitin was observed in 28 of the isolated strains. 12 isolatesexcreted a detectable extracellular chitinase.[1] Henrissat, B. and G. Davies (1997): 7:637-644.[2] Keyhani, N.O. and S. Roseman (1999): BBA-General Subjects 1473:108-122.[3] LeCleir, G.R. et al (2004): Applied and environmental microbiology 70:6977-6983.[4] Poulicek, M. and C. Jeuniaux (1991): Biochemical Systematics and Ecology 19:385-394.MDP010Microbial communities on indwelling urinary tractcathetersM. Burghartz*, D. Zwerschke, M. JahnInstitute for Microbiology, University of Technology, Braunschweig,GermanyCatheter associated urinary tract infections (CAUTI) are diagnosed formillions of patients per years. They constitute 40 % of all nosocomial,mostly asymptomatic infections. Usually, after four weeks biofilm formationoccurs on every catheter.Multiple microbial species have been identified from catheter biofilms byusing culture-dependent techniques. The most frequently found species areEnterobacteriaceae besides Pseudomonas aeruginosa and the Gram positiveStapylococci and Enterococci. But as known from other environmentalanalyses many more different species can be detected via the cultureindependent methodology than isolated.Aim of this work is the identification of microorganisms from urinary tractcatheter biofilms by using culture-independent methods. To determine thestructure of the microbial community PCR-SSCP using universal 16S rRNAgene primers was performed.A total number of 91 catheters were analysed. The communities consist ofvarious Gram positive as well as Gram negative bacteria. Preliminary resultsshowed that in catheters used for the first time on patients as well as infollow-up catheters the Lactobacillales and the Enterocacteriales weredominant. The populations did not shift significantly except for the absenceof Pseudomonadales in the secondary catheters. Further obligat anaerobicbacteria could be detected (e.g. Peptoniphilus harei). The most frequentbacteria were E. faecalis, Aerococcus urinae and P. mirabilis.Elucidation of the precise microbial community structure may enhance theopportunities for new directed antibiotic therapies or for the development ofnovel antimicrobial surfaces.MDP011Microbial diversity and changes in communitycomposition in lab-scale biogas reactors depending ondifferent substratesK. Kampmann* 1 , I. Kramer 1 , M. Schmidt 2 , W. Zerr 2 , S. Ratering 1 ,S. Schnell 11 Institute of Applied Microbiology, Justus-Liebig-University, Gießen,Germany2 Hessian State Office Laboratory,Bad Hersfeld, GermanyProduction of biogas from agricultural resources involves a diversecommunity of different microorganisms. However, little is known aboutwhich species play key roles for the degradation of certain substrates inbiogas plants. This knowledge could help to improve fermentation processesand enhance biogas formation by optimizing the conditions for these keyorganisms. Therefore lab-scale biogas reactors with volumes of 20 and 200liters were set up. Reactors were started with a mixture of 70 % cow manureand 30 % pig manure to which different substrates like casein, starch andcellulose were added. First, a clone library was constructed in order toidentify the most important groups of Bacteria in the basis feedstock forfurther analyses. These turned out to be Bacteroidetes and Firmicutes.Additionally, two subgroups of Firmicutes were investigated separately:Lactobacillales and Clostridia Cluster XIVa as well as Bacteria in generaland methanogenic Archaea. Changes in the corresponding microbialcommunities were investigated with the help of SSCP (Single StrandConformation Polymorphism) analyses. DNA fragments from predominantSSCP-bands were cloned and taxa identified by sequencing. Furthermore,quantifications of all microbial groups of interest were carried out by realtimePCR.First results of SSCP analyses showed two dominant species ofmethanogenic Archaea for casein, starch and whipping cream as substratesfor biogas production. DNA sequences found in these SSCP gels belongedto the genera Methanospirillum and Methanobrevibacter that are unable todegrade acetate. Corresponding SSCP band patterns did not show distinctchanges with different substrates. Copy numbers of the mcrA gene encodingthe methyl-CoM reductase calculated by real-time PCR resulted in about 10 8per g dry matter (dm).For Firmicutes and Bacteroidetes, six to seven and four to seven dominantspecies, respectively, could be observed depending on the substrate. In realtimePCR analyses, copy numbers of the corresponding 16S-rRNA genefragments of about 10 9 per g dm for Firmicutes and 10 10 per g dm forBacteroidetes could be observed. In order to distinguish between presenceand activity of the microorganisms, RNA-based analyses will follow.MDP012Population structure of aquatic SphingomonadaceaeH. Chen*, M. Jogler, J. OvermannMicrobial Ecology and Diversity Research, German Collection ofMicroorganisms and Cell Cultures (DSMZ), Braunschweig, GermanyThe role of recombination, adaptation and selection in shaping bacterialdiversity was assessed using aquatic members of the Sphingomonadaceae(Alphaproteobacteria) as a model group. Our multilocus sequence analysis(MLSA) targets a set of 9 housekeeping genes (atpD, dnaK, EF-G, EF-Tu,gap, groEL, gyrB, recA, rpoB) in Sphingomonadaceae and was used toelucidate the population structure and the significance of recombinationevents in this group. The new MLSA primers were designed based on allavailable genome sequences of 5 strains of Sphingomonadaceae and 2strains of the closest phylogenetically related genus Erythrobacter. A totalof 95 strains of Sphingomonadaceae were isolated from Starnberger See andWalchensee, and subjected to the novel MLSA approach. Based on theirrRNA gene sequences, these strains fall into three different phylogeneticspektrum | Tagungsband 2011