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

Dinoroseobacter shibae for our knock-out strategy [2]. The constructincluding a gentamycine resistance cassette was transformed into strainDSM 17395 and thus induced the loss of the indigenous plasmid.The plasmid knock-out mutant and the wild type strain were compared usingthe Phenotype MicroArray technology (PM; Biolog, USA). With thissystem nearly 2000 cellular phenotypes can simultaneously be tested in amicrotiter plate format. To establish PM data for P. gallaeciensis and othermembers of the Roseobacter clade, we optimized the assay conditionsregarding salt concentration, vitamins and micronutrients. We focused ourinitial experiments on plates PM 1 and 2, in which 190 different carbonsources are tested, and analyzed the respective kinetics.Comparing the metabolic activity of the mutant and the wild type strain inPM 1 and 2, we observed kinetic differences in the conversion of manysubstrates and it was revealed that the mutant was unable to metabolize fourcarbon sources. Surprisingly, rhamnose was not converted at all. Themannose metabolism showed a reduced metabolic response in case of themutant. The functional role of the 65 kb plasmid in P. gallaeciensis will beinvestigated by comparing mutant and wild type strain via biofilm assays.[1] Laus, M.C. et al. (2006): A novel polar surface polysaccharide from Rhizobium leguminosariumbinds host plant lectin. Mol. Microbiol. 59(6): 1704-13.[2] Petersen, J. et al. (2010): Origin and evolution of a novel DnaA-like plasmid replication type inRhodobacterales. Mol. Biol. Evol.: advanced access.[3] Pradella S. et al. (2004): Genome organization and localization of the pufLM genes of thephotosynthesis reaction center in phylogenetically diverse marine alphaproteobacteria. Appl. Environ.Microbiol. 70: 3360-69.[4] Wagner-Döbler, I. et al. (2010): The complete genome sequence of the algal symbiontDinoroseobacter shibae: a hitchhiker`s guide to life in the sea. ISME J. 4: 61-77.MDP020The influence of plant surface characteristics onnaturally colonizing bacterial communities of Arabidopsisthaliana leavesE. Reisberg*, U. Hildebrandt, M. Riederer, U. HentschelJulius-von-Sachs Institute for Biosciences, Botany II, Julius-Maximilians-University, Würzburg, GermanyThe phyllosphere of plants represents a suitable habitat for microorganisms.In our study we aim to characterize the role of specific plant surfacecharacteristics of A. thaliana and its natural bacterial inhabitants. Severalstudies have indicated that plant trichomes may affect microbial colonizationof the phyllosphere. In a first project, the A. thaliana ecotype Col-0 and itsgl1 mutant, devoid of trichomes on the leaf surface, were compared withregard to bacterial community diversity on their leaf surfaces. Comparativeanalyses were performed using cultivation independent denaturing gradientgel electrophoresis (DGGE). DGGE banding patterns and sequencing ofrepresentative DGGE-bands showed only minor differences between the twoplant lines suggesting that the presence of trichomes per se does not affectbacterial diversity. In a second project, we seek to investigate whether thevery-long-chain alkanes known to be present on the A. thaliana cuticle serveas a substrate for bacterial growth. Bacterial communities derived from A.thaliana ecotype Ler leaf surfaces were grown in enrichment cultures withmineral salts medium overlaid with C 16 alkane or with addition of C 22 alkaneas a sole carbon source. 16S rRNA gene sequencing and phylogeneticanalyses of bacterial isolates from the enrichment cultures classified most ofthe isolates as Rhodococcus species, which are well known alkane degradersoccuring in mineral oil contaminated environments. Our future efforts aredirected towards analyzing the capability of isolated phyllosphere bacteria tometabolize and to degrade other cuticular wax constituents.MDP021Analyzing the biofilm-forming microbiota in a biogasprocessing plant by 454-PyrosequencingF. Bengelsdorf* 1 , M. Zak 2 , U. Gerischer 3 , M. Kazda 21 Institute for Microbiology & Biotechnology, University of Ulm, Ulm,Germany2 Institute of Systematic Botany and Ecology, University of Ulm, Ulm,Germany3 Max Planck Institute for Biophysical Chemistry, Göttingen, GermanyThe resident microbiota was analyzed by 454-Pyrosequencing in amesophilic, continuously operating biogas digester supplied with foodleftovers,stale bread and liquid pig manure. Substrates like food-leftoversand stale bread possess low structure but provide a high energy potential interms of carbohydrates, proteins as well as fat. Fast fermentation on theother hand poses a high risk to overload the whole process. In fermentationexperiments at laboratory scale (4 parallels, 10 L digester) 5 g/l of straw of 2cm length was supplied as additional surfaces for biofilm formation. Theseamendments stabilized the biogas processes especially at increasing organicloading rates. With that purpose an adequate amount of straw as a biofilmcarrier was added to a fermenter (300 m 3 ) of a full-scale biogas plant. The454-Pyrosequencing study was used to compare the microbial compositionattached to the straw to them with the liquid fermenter content.Therefore, the sample A was taken from the fermenter before the straw wasadded to the process. Simultaneously, a labscale fermentation was startedand operated continuously. After 21 days of fermentation the sample B wastaken from labscale biogas experiment and sample C was taken from thefull-scale biogas plant. The fluid fermenter content form samples A, B and Cwas sieved and the microbial biomass attached to particles (A) and the straw(B and C) was removed with a sterile swap. The six samples obtained wereused for genomic DNA preparation and amplification of bacterial andarchaeal 16S rDNA.The 454-Pyrosequencing of pooled 16S rDNA products resulted in a total of101269 16S rDNA sequences. Allover 44 % belong to bacteria and 56 % tothe archaea. About 52 % of the sequences belong to the samples of the fluidfermenter content and 48 % to the samples of biofilm-forming microbiotaattached to straw or particles.MDP022The effect of forest management intensity on the diversityof wood-decaying fungi and deadwood decompositionT. Arnstadt* 1 , B. Hoppe 2 , T. Kahl 3 , D. Krüger 2 , J. Bauhus 3 , M. Hofrichter 11 Unit of Environmental Biotechnology,International Graduate School (IHI)Zittau, Zittau, Germany2 Helmholtz Center for Environmental Research (UFZ), Halle, Germany3 Institute of Silviculture, Albert-Ludwigs-University, Freiburg i.Br.,GermanyDead wood, also referred to as coarse woody debris (CWD), is a key habitatelement in all forest ecosystems and is decayed by various types oforganisms such as insects, bacteria and fungi. Among the latter, chieflyBasidiomycota (white- and brown-rot fungi) and a few Ascomycota (soft-rotfungi) are the main wood decomposers. To accomplish lignocellulosesdegradation, they actively secrete different sets of oxidative and hydrolyticbiocatalysts. Here, we report on the change in dead wood fungal diversityalong a forest management intensity gradient and its influence on wooddecay and ecosystem processes such as lignin degradation and secretion ofoxidative enzyme activities.We selected around 200 CWD locks of different decay stages and diameterin the Biodiversity Exploratories in Germany (Schorfheide-Chorin, Hainich-Dün and Schwäbische Alb). In each Exploratory are nine plots with differentmanagement intensities (unmanaged, age-class forest and selection forest).We took from all locks up to five samples. These samples were analysed forKlason Lignin and water-soluble fragments with aromatic properties (UVabsorption band at 280 nm). Also the enzyme activities of laccases andperoxidases (manganes in- and dependent) were measured.In this poster, we focus on the following questions: How do the content oflignin and water-soluble aromatic fragments of CWD as well as enzymeactivities of laccases and peroxidises in CWD vary in dependency oncolonization patterns of wood-decaying fungi and on the different decaystages?MDP023Molecular biodiversity of Mycobacterium tuberculosisisolates from patients with pulmonary tuberculosis inBulgariaV. ValchevaInstitute of Microbiology, Pathogenic Bacteria, Sofia, BulgariaIntroduction: Tuberculosis remains an important public health issue forBulgaria and other Balkan countries located in the world region withcontrasting epidemiological situation. The rate of multidrug-resistant strainsamong newly diagnosed TB patients in Bulgaria was estimated to be 10.7%that is much higher than in the neighbouring countries. The prediction ofdrug resistance by molecular tools presents a correct and rapid detection ofresistant strains for timely anti-TB therapy and constitute one of thepriorities of the national TB control program.Methods: The study set included all available DNA samples isolated inseveral provinces across Bulgaria were analyzed by various molecularspektrum | Tagungsband 2011