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

[1] Klijn, A. et al (2006): Appl. Eviron. Microbiol. 72 (11): 7401-5.[2] Guglielmetti, S. (2008): Appl. Environ. Microbiol. 74 (15): 4695-702.SIP017Impact of diet on the gut microbiota of the cockroachShelfordella lateralisC. Schauer*, C. Thompson, A. BruneMax Planck Institute for Terrestrial Microbiology, Marburg, GermanyThe dietary requirements of termites and cockroaches are distinctlydifferent. While termites consume a highly specialized diet of lignocellulosethat is digested with the help of a specialized gut microbiota, cockroachesare omnivorous and opportunistic feeders. Our analysis of the bacterialcommunity in the hindgut of Shelfordella lateralis, revealed a diverse gutmicrobial community that comprised many lineages clustering withsequences from termite gut, reflecting the close phylogenetic relationshipbetween cockroaches and termites. It is not clear, however, whether thehindgut community is also influenced by diet. Here we examine the effectsof different diets on the colonic gut microbiota of Shelfordella lateralis. Thecockroaches were fed one of four diets: chicken food (balanced), soy(protein-rich), bran, and bran-cellulose (fibre-rich). Although colon weightwas significantly greater in cockroaches that were fed a high fibre diet, therewere no significant effects of diet on volatile fatty acid concentrations ormethane production. Analysis of bacterial community structure by terminalrestriction-fragmentlength polymorphism and 454 pyrosequencing of 16SrRNA genes revealed a high individual variability but little impact of diet.Each cockroach seems to maintain a core gut microbiota that is insensitive todietary shifts.SIP018A gene of the multidrug and toxic compound extrusion(mate) family in the ectomycorrhizal fungus TricholomavaccinumI. Schlunk*, E. KotheDepartment of Microbial Phytopathology, Friedrich-Schiller-University,Jena, GermanyAll over the world fungi can be found in different habitats and in interactionwith a multiplicity of organisms. This widespread distribution and thecontact to other organisms have a lot of advantages but also bear the risk ofhaving contact to antagonistic defense mechanisms including toxiccompounds. To prevent their cells from these substances a lot of facilitiesare given. One possibility is the extrusion via multidrug transporters. Theseproteins can transport toxic substances out of the cell and save the cells fromdamages. Because of the high number of transporters in the membrane onlya part of these proteins is well investigated yet. A new familiy of multidrugtransporters are the proteins from the multidrug and toxic compoundextrusion (MATE) family. For some orthologes in human, bacteria andplants their role in detoxification is understood. They can transport e.g.chemotherapeutics, antibiotics and secondary plant metabolites. In fungionly ERC1 (ethionine conferring resistance) from S. cerevisiae is describedas being responsible for accumulation of ethionine when it is overexpressedin the cell. Like most fungi yeast has two MATE paraloges. Both strainswere used for heterologues expression experiments with a MATE gene fromthe ectomycorrhizal fungus Tricholoma vaccinum, mte1. It could be shown,that Mte1 is responsible for the detoxification of different compounds asmetals, xenobiotics, dyes and secondary plant metabolites.SIP019Effect of associated Pseudomonas bacteria and theirsecondary metabolites on the resistance of black alderagainst pathogenic Phytophthora alniT.L.H. Pham 1 , I. Zaspel* 21 Institute for Ecology, University of Technology, Berlin, Germany2 Federal Research Institute for Rural Areas, Forestry and Fisheries (vTI,Institute of Forest Genetics, Waldsieversdorf, GermanySince two decades, Phytophthora alni (Oomycetes) causes the disease ofalder (Alnus spp.) decline in Europe and has been posing a serious threat toyoung, adult riparian and forest alder stands. The disease is distributed bymobile zoospores in water systems and thus could establish itself in wholeCentral Europe within short time. In Germany, the pathogen is present in themost riparian and forest alder stands. An effective control against P. alni iscurrently not available. However, a stagnating disease progress can beobserved in some areas in the meantime. Beside climatic and genetic factors,it is assumed that the native soil microflora contributes to the regulation ofthe pathogen and disease decline.Our Phytophthora alni isolates, grown on different culture media, wereassociated regularly with bacteria, which have been isolated and identifiedas Pseudomonas veronii-like strain PAZ1 and Pseudomonas sp. PAZ43. Invitroand in-vivo plant tests as well as antagonist tests clearly revealed thatthese Pseudomonas strains and their secondary metabolites support thegrowth of alder roots and inhibit the growth of P. alni, respectively. Thetreatment of plantlets resulted in a distinct promotion of root and shootgrowth under sterile conditions and a slower infection course by thepathogen although differences between the alder clones existed. Undergreenhouse conditions, the infection of plants was reduced by the half afterthe cultivation time of 12 months. This study demonstrated the positiveeffects of associated Pseudomonas and their metabolites on the promotion ofconstitutive resistance of black alder against P. alni. Because of that, we areespecially interested on these Pseudomonas strains and their metabolites.The structure of secondary metabolites of associated Pseudomonas strainshas been elucidated by means of LC-ESI-Q-TOF-MS and -MS/MS as wellas H/D-Exchange-MS/MS and -Pseudo-MS 3 . About 50 cycliclipodepsipeptides (with 9 or 8 amino acids) were found from Pseudomonasveronii-like strain PAZ1. More than 50 % of them have been detected for thefirst time and belong to the group of the antibiotic active main CLP viscosin.37 cyclic lipodepsipeptides were found from Pseudomonas sp. PAZ43. 30 ofthem belong to the group of novel cyclic lipodepsidecapeptides with 3-hydroxydecanoic acid as lipid moiety.SIP020A natural prodrug-mechanism in secondary metabolismD. Reimer*, H.B. BodeInstitute for Molecular Bio Science, Goethe-University, Frankfurt am Main,GermanyBacteria of the genus Xenorhabdus live in symbiosis with entomopathogenicnematodes of the genus Steinernema and are pathogenic against numerousinsect larvae. By producing insect-toxic proteins and other unknown factorsthe insect larvae is killed within 24h post-infection [1-3]. As there have beenhints that secondary metabolites produced by the bacterium are eitherinvolved in the pathogenesis against the insect or play an important role inthe symbiosis towards the nematode [4], we investigated the biosynthesis ofsecondary metabolites produced by these bacteria with a special focus onnon-ribosomal peptide synthetases (NRPS) and polyketide synthesis (PKS).Xenocoumacin-1 (XCN-1), a potent antibiotic and antifungal compound andthe only weakly active XCN-2 are the main antibiotics produced byXenorhabdus nematophila [5].During our effort to understand the xenocoumacin biosynthesis, we couldidentify and characterize four new derivatives and the correspondingbiosynthesis gene cluster. Additionally, we confirmed that XCN-2 is derivedfrom XCN-1, representing a novel mechanism for pyrrolidine ring formation[6]. Additionally, deletion of xcnG encoding a bifunctional protein with apeptidase and transmembrane domains led to a complete loss of XCNproduction. Instead, five new compounds, extended XCN derivatives with aD-Asn and a fatty acid, named prexenocoumacins (PreXCN) were produced.Encouraged by these results, we postulated the following model: PreXCN,which are not active and act as a prodrug for XCN are formed inside thecytoplasm. While exported into the periplasm by XcnG, all PreXCN arecleaved into the active XCN-1, which kills competing bacteria. As X.nematophila itself is sensitive to XCN-1 [7], XCN-1 is converted into XCN-2.spektrum | Tagungsband 2011