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

EMP005Identification of indigenous bacteria in an As-highaquifer of Hetao Basin, ChinaX. Tang* 1 , T. Schwartz 2 , H. Guo 3 , S. Norra 1,41 Institute for Minerology and Geochemistry (IMG), Karlsruhe Institute ofTechnology, Karlsruhe, Germany2 Institute of Functional Interfaces, Karlsruhe Institute of Technology,Eggenstein-Leopoldshafen, Germany3 School of Water Resources & Environment, China University ofGeosciences, Beijing, China4 Institute of Geography and Geoecology, Karlsruhe Institute of Technology(KIT), Karlsruhe, GermanyEndemic arsenicosis poses a huge threat to habitant’s health in the areas withhigh arsenic concentration of Hetao Basin, China, where As concentrationsrange between 1 and 1000 μg/L. Here, a significant proportion (up to 90%)of the As occurs as As (III). From a geological, geochemical andmicrobiological viewpoint, there are many studies trying to find the sourcesof high arsenic concentration in groundwater. Recently, it is generallyaccepted that microbial activities play a critical role in the releasing ofarsenic from the sediments.Four drillings were carried out in aquifers with different As concentrationlevels in Hetao Basin. Polymerase chain reaction (PCR) and denaturinggradient gel electrophoresis (DGGE) were used to identify relevant bacteriaspecies responsible for As release in different sediments of those drillings.The sediments with indigenous bacteria were cultured with DEV-agar plates.For this experiment, 300 μg/L As (V) were added and the growingconditions were comparable to the aquifer conditions on-site.The PCR-DGGE profiles indicated that the bacteria species, which can growwell with high-As concentration under lab conditions, were very differentfrom the indigenous bacteria that were found in the raw sediments.Comparative sequence analyse for the raw sediment revealed various DNAband patterns, suggesting a population shift in different depths and differentsediments. Some bacteria, which may affect the release and mobilization ofAs in aquifer, like iron-reducing bacterium, Siderooxidans paludicola andNovosphingobium hassiacum were found in the sediments. There are manyarsenic resistant bacteria, which have isolated from the incubations. Forexample Pseudomonas sp., which is gram-negative, rod-shaped, non-motile,non-spore-forming, and noncapsulated, is a very efficient As (V) reducingbacterium. The DGGE profiles also indicated that most of indigenousbacteria species had high G+C, but most of bacteria that were incubated inlab had low G+C.EMP006Bacteria associated with coexisting macroalgae: seasonal,interspecies variation and antibiotic effectsF. Goecke Saavedra*, A. Labes, J. Wiese, J.F. ImhoffKieler Wirkstoffzentrum at the Leibniz Institute of Marine Sciences IFM-GEOMAR, FB3 - Marine Mikrobiologie, Kiel, GermanyBacteria associated with 2 macroalgae, a brown and a red macroalga,coexisting in the Kiel Fjord (Baltic Sea, Germany) were investigatedseasonally by scanning electron microscopy and cultivation methods.Significant differences between both macroalgal species with regard to theirassociated bacteria and seasonal variations were observed.166 bacterial strains were isolated from both macroalgae and classified byphylogenetic analysis of 16S rRNA gene sequences. The strains belonged to82 phylotypes according to sequence similarities of >99.0%. They affiliatedto Actinobacteria, Alphaproteobacteria, Bacilli, Betaproteobacteria,Flavobacteria, Gammaproteobacteria, and Sphingobacteria. Samples fromFucus vesiculosus revealed 43, and samples from Delesseria sanguinea 57phylotypes. Certain phylotypes are consistently found as epiphytes,suggesting their specific association to macroalgae.Culture extracts of all bacteria were tested for antimicrobial activity. Morethan 60% of the phylotypes inhibited the growth of at least onemicroorganism of a standard and an ecologically relevant test panel (Grampositiveand Gram-negative bacteria, including macroalgal pathogens andsurface associated strains, and one yeast). A higher proportion of the strainsshowed antimicrobial activity against the ecologically relevant bacteria ascompared to the standard set of microorganisms. In contrast, extracts of themacroalgae presented only a weak inhibition of test panel microbes, but ageneral growth stimulating effect on the macroalgae-associated strains.Significant activity of the associated bacteria against macroalgal pathogensand competitors and the stimulating effect of the algal host extracts indicatespecific functions and adaptations of these bacteria to algal host and viceversa.EMP007Biogeochemical mobilization of arsenic from aquifersediments in West Bengal, IndiaH. Neidhardt* 1 , D. Freikowski 2 , Z. Berner 1 , A. Biswas 3 , S. Norra 1 ,J. Winter 2 , D. Chatterjee 31 Institute of Mineralogy and Geochemistry, Karlsruhe Institute ofTechnology (KIT), Karlsruhe, Germany2 Institute for Biology for Engineers and Biotechnology of Waste WaterTreatment, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany3 Department of Chemistry, University of Kalyani, Kalyani, IndiaThe aim of this field experiment was to test the potential role ofmicroorganisms in the occurrence of As-rich groundwater, by stimulatingthe activity of indigenous microbial populations within a shallow aquifer, inWest Bengal, India. Local groundwater is of Ca-HCO 3 - -type andhydrochemical parameters indicate low redox conditions, in the range ofiron reduction.Sucrose was inserted as readily degradable organic carbon source into fivenested monitoring wells by circular pumping, thus generating concentrationsfrom 8.3 to 873 mg/L within the screened depth intervals from 12 - 44 m.For the following 14 days, field parameters were measured and watersamples were taken every second day to examine the geomicrobiologicaleffects involved in the mobilization of As. Significant changes inhydrochemical parameters have been observed soon after insertion,indicating that the microbial stimulation was successful. Sucroseconcentrations decreased continuously, while degradation products likeacetate were formed, disturbing the hydrogeochemical equilibrium in thewater-sediment-system. Formation of organic acids (like acetate anions) ledto a partial dissolution of carbonates. The absence of dissolved oxygen,nitrate and sulphate combined with a strong increase in the concentration ofdissolved Fe II (up to 36 times relative to its initial value) indicates ongoingdissimilatory Fe-reduction, which is believed by many authors to beresponsible for As mobilization (e.g. [1]). Dissolved As concentrationsshowed a considerable temporary increase of up to 49% of the initial value.Nevertheless, this increase appeared to be relatively low as compared to themobilization of other trace elements, most likely also associated with Feoxyhydroxides.Our field experiments strongly support the assumption thatthe mobilization of As is primarily influenced by the biotransformation ofFe-mineral phases [2; 3]. The dissolution of some mineral phases (e.g. Feoxyhydroxides,carbonates, etc.), and the mobilization of associated traceelements, including As, is controlled to a large extent by microbialmetabolism, which ultimately depends on the availability organic electrondonors in the groundwater environment.[1] Islam, F. S. et al (2004): Role of metal-reducing bacteria in arsenic release from Bengal deltasediments. Nature, 430, 68-71.[2] Kocar, B.D. et al (2006): Contrasting Effects of Dissimilatory Iron(III) and Arsenic(V) Reductionon Arsenic Retention and Transport. Environ. Sci. Technol., 40, 6715-6721.[3] Tufano, K.J and S. Fendorf (2008): Confounding impacts of iron reduction on arsenic retention.Environ. Sci. Technol., 42, 4777-4783.EMP008Identification of nitrifying bacteria in activated sludgeH. Stryjová*, J. WannerInstitute of Chemical Technology Prague, Department of Water Technologyand Environmental Engineering, Prague, Czech RepublicNitrogen removal is an important process in wastewater treatment system.Nitrifying bacteria have slow growth rates and are sensitive to toxic shocks,pH- and temperature swings. This is the reason why many wastewatertreatment plants (WWTPs) fail to establish stable nitrification. The microbialecology of nitrifying bacteria from Czech WWTPs was investigated usingfluorescence in situ hybridization (FISH) with 16S rRNA-targetedoligonucleotide probes. This paper is focused on detection of single cells orvarious clusters of nitrifying bacteria in activated sludge samples taken fromsewage WWTPs. Bacteria were identifying and quantifying usingepifluorescence microscopy and image analysis.spektrum | Tagungsband 2011