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

EMP100Microbiological water quality including pathogenicbacteria and parasites along the river RhineB. Hambsch* 1 , M. Hügler 1 , W. Hoogenboezem 2 , J. Meyer 3 , H.-P. Rohns 4 ,S. Schneider 5 , F. Wirtz 61 Department of Microbiology, Water Technology Center (WTZ), Karlsruhe,Germany2 Het Water Laboratorium, Haarlem, Netherlands3 Lake Constance Water Supply, Sipplingen, Germany4 Stadtwerke Dusseldorf, Dusseldorf, Germany5 Hessenwasser GmbH & Co. KG, Darmstadt, Germany6 IAWR, Cologne, GermanyThe European water framework directive 2000/60/EG aims to protect waterand to promote water use based on a long-term protection of water resourcesby using ecological and chemical parameters.The commission Biologists within the International Association of theWaterworks in the river Rhine catchment area (IAWR) concluded that theseparameters are not sufficient to describe the quality of a water body.Especially microbiological aspects are totally missing, but are mostimportant for hygienic aspects of recreational activities and safe drinkingwater production. Therefore it was decided to do a survey to investigate theriver water quality by health related microbiological parameters.The microbiological parameters included on one hand fecal indicators (E.coli, coliform bacteria, enterococci, Clostridium perfringens and somaticcoliphages) and on the other hand pathogenic microorganisms, namelythermotolerant Campylobacter and the parasites Cryptosporidium andGiardia. Samples were taken at two dates in summer 2009 at three differentsampling points from Rhine-km 0 up to Rhine-km 865.The results of this monitoring program will be presented and discussed. Thenumbers of the bacterial fecal indicators as well as those of the somaticcoliphages increased in direction of the flow of the river Rhine. Thepathogenic parasites Cryptosporidium and Giardia were detectable in therange of 1 to 20 cysts in samples of 100 L. The pathogenic Campylobacterwere not detected. The most probable reason was the high water temperature(>25°C) during the sampling dates. Since the survival rate of Campylobacterbacteria is higher at lower temperature, further sampling at lower watertemperatures would be needed.In summary, it seems important to add microbiological parameters into aframework directive for the protection of water.indicate that (i) denitrifiers and dissimilatory nitrate reducers in theearthworm gut are soil derived, (ii) these functional groups are selectivelyactivated and likely compete for inorganic nitrogen during gut passage, and(iii) feeding guilds affect this selective activation.EMP102Co-regulation of multidrug resistance and pathogenicityin the plant pathogen Erwinia amylovoraG. Schweizer*, N. Al-Karablieh, M.S. Ullrich, H. WeingartSchool of Engineering and Science, Jacobs University, Bremen, GermanyErwinia amylovora is the causative agent of the plant disease fire blight,with economic importance on apple and pear. During pathogenesis, thebacterium is exposed to a variety of plant antimicrobials. The bacterialmultidrug efflux system AcrAB-TolC, which mediates resistance towardstructurally unrelated compounds, was shown to confer resistance to thesephytoalexins. While investigating AcrAB-TolC in E. amylovora, a linkagebetween multidrug efflux and pathogenicity has been discovered: a tolCdeficientmutant was impaired in multiplication in plant tissue and did notcause characteristic symptoms of fire blight on apple. Moreover, SDS-PAGE analysis of extracellular proteins showed that a hrp-associatedvirulence protein is no longer secreted by the tolC mutant.A link between antibiotic resistance and pathogenicity was also found inother enterobacteria, e.g. Salmonella enterica. An intact AcrAB-TolCsystem is required for the colonization, and persistence, of these bacteria inthe host. Mutants lacking acrB, or tolC showed decreased expression ofmajor operons and proteins involved in the pathogenic process. Members ofthe AraC/XylS family of regulators, e.g. marA, soxS, rob and ramA, havebeen shown to activate expression of RND efflux pumps inEnterobacteriaceae. Furthermore, overexpression of ramA in Salmonellaenterica lead to decreased expression of virulence genes suggesting that theregulation of multidrug efflux systems and expression of virulence genesshow considerable overlap.This project aims to identify similar regulators in E. amylovora. A BLASTsearch was used to identify homologous sequences in the available genomesequences. Overexpression of the homologous genes will be used toinvestigate the influence of the regulators on multidrug resistance by usingMIC assays and on virulence by determination of in planta growth.EMP101Activation of nitrous oxide-producing nitrate reducersduring gut passage through earthworms of differentfeeding guildsP.S. Depkat-Jakob*, M. Hilgarth, J. Gebelein, M.A. Horn, H.L. DrakeDepartment of Ecological Microbiology, University of Bayreuth, Bayreuth,GermanyNitrous oxide (N 2O) is emitted by the earthworm, and the anoxic conditionsof the gut might stimulate ingested nitrate-reducing soil bacteria linked tothis emission. Thus, denitrifiers and dissimilatory nitrate reducers in theearthworm gut of three different feeding guilds (epigeic [Lumbricusrubellus], anecic [Lumbricus terrestris], and endogeic [Aporrectodeacaliginosa]) were investigated. NarG (encodes for a subunit of nitratereductase) and nosZ (encodes for a subunit of N 2O reductase) were detectedin the earthworm gut and surrounding soils at both gene and transcriptlevels. NarG transcripts related to nitrate dissimilators were detected in gutcontents. NirS (encodes for a nitrite reductase) was examined at gene levelin gut and soil of L. terrestris. Gut-derived sequences of all three genesdisplayed high similarity to soil bacteria and soil-derived sequences. GutderivednarG sequences and terminal restriction fragments (TRFs) weremainly affiliated with gram positive organisms at both gene and transcriptlevels. Most transcripts were closely related to Mycobacterium-affiliatedsequences. Sequences related to Gram negative bacteria were dominant inmineral soil. nosZ sequences and TRFs at both gene and gene expressionlevels belonged mostly to Alphaproteobacteria, with high similarity toBradyrhizobium japonicum and uncultured soil bacteria. Differencesbetween gut-derived and mineral soil-derived sequences were large at thetranscript level but minimal at the gene level. Feeding guilds affected thedetected nosZ community at the gene level and to an even greater extent atthe transcript level. Feeding guilds also affected the detected narGsequences at the gene level but had minimal impact on narG expression.Most nirS sequences were affiliated with those related to Bradyrhizobium,Rhodanobacter, and uncultured soil bacteria. These collective observationsEMP103Long-term investigations of natural remediationprocesses: adaptation of microbial wetland communitiestowards high loads of petrochemical aromaticcompoundsI. Fetzer* 1 , A. Chatzinotas 1 , C. Härtig 1 , H. Harms 1 , B. Kiesel 1 ,S. Kleinsteuber 1 , S. Müller 1 , J. Rakoczy 2 , H.-H. Richnow 2 , D. Schlosser 1 ,C. Vogt 21 Department of Environmental Microbiology, Helmholtz Center forEnvironmental Research (UFZ), Leipzig, Germany2 Department of Isotope Biogeochemistry, Helmholtz Center forEnvironmental Research (USZ), Leipzig, GermanyWithin a long term project on compartment transfer (CoTra Project) at aformer refinery site near Leuna (Germany) a semi-natural wetland was setup to investigate natural microbial degradation processes of petrochemicalaromatic compounds (7 mg/l MTBE, 23 mg/l BTEX) under controlled,semi-natural conditions. The wetland (5m x 2.3m x 1.1m) is split into aplanted (Carex spp.) and an unplanted section. Contaminated groundwaterfrom the area is introduced at 11 l/h (~24d residence time). Saturation of>75% of the aromatic compound inflow concentration was reached alreadyafter one week. After 19 weeks the system became fully saturated andanoxic in the deeper layers, indicating the onset of microbial degradationprocesses. Sediment-bound bacterial biomass was generally higher inplanted section. Flow cytometry analysis revealed high annual bacterialcommunity dynamics. Beside bacteria, also fungi and phages obviouslyseem to play an important role in the system. No differences of pollutantremoval rates between planted and unplanted section were detectable duringthe first season, but started to differ significantly after the following secondseason (~20% for MTBE and BTEX for unplanted; >60% for planted).However, pollutant breakdown efficiency of both strips strongly changedwith season and temperature. In general, degradation processes werestrongly enhanced by deep-going plant roots and soil-water transition layers,probably due to oxygen transport into deeper section and creation ofspektrum | Tagungsband 2011