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

eduction was found to be the dominant redox process coupled to BTEX andPAH oxidation. Five years of repeated sampling revealed pronouncedvertical dynamics of physical-chemical and microbial gradients includingthe spreading of the contaminants with time. These dynamics can behypothesized to either enhance (via increased mixing) or hamper (bydisturbance of established sessile degrader populations) net contaminantremoval. There is serious evidence from compound specific stable isotopedata and from microbial community analysis that minor hydraulic changeshave the potential to impair key degrader populations. Now, the timescale ofthe temporal and spatial dynamics of biodegradation is focus of our currentwork. It is still poorly understood how attached microorganisms cope withthe unpredictable changes in environmental conditions and how fast they canadapt to the changing redox conditions. Recently, three sampling campaignsproved short-term dynamics for e.g. toluene, sulfate and sulfide along avertical plume cross section. While microbial patterns, i.e. total cell numbersand active biomass (ATP) lagged behind. In conclusion, severelycontaminated sites with highly specialized anaerobic degrader populationsare characterized by low resilience. Minor and short-term hydrogeochemicaldynamics were found to interfere with effective overall biodegradation, withdegraders lacking behind the associated physical-chemical changes.EMP022Niche partitioning among nitrite-oxidizing bacteriaE. Spieck*, S. Off, S. KeuterDepartment of Microbiology and Biotechnology, University of Hamburg,Hamburg, GermanyNitrification is of fundamental significance for the global nitrogen cycle andrecent discoveries of novel microorganisms refreshed the traditionaltextbook knowledge. Chemolithoautotrophic nitrite-oxidizing bacteria(NOB) perform the second step of nitrification and, in contrast to ammoniaoxidation, no archaea were identified so far to perform this reaction. NOBare phylogenetically diverse and belong to different subclasses of theProteobacteria or the deeply branching phylum Nitrospirae. An increasingdiversity of novel strains and even genera became available when the growthparameters were better adapted to natural conditions. With regard to theirultrastructure, NOB can be separated into two groups, characterized by thepresence or absence of intracytoplasmic membranes (ICM). NOB withoutICM, like Nitrospira and the new candidate genus Nitrotoga, possess anextended periplasmic space, which serve as cell compartment for the energygaining reaction. Simultaneously, Nitrospira, Nitrospina and Nitrotoga areadapted to low substrate concentrations, whereas Nitrobacter andNitrococcus containing ICM are very tolerant against nitrite. Besides nitrite,temperature has been identified as another ecophysiological factordetermining niche separation. For example, Nitrotoga was detected inpermafrost-affected soils and prefers temperatures below 20°C. The mostversatile genus Nitrospira occurs in a wide range of habitats and dominatesin geothermal springs with temperatures up to 60°C, where a coexistence ofseveral new species was found. Additionally, Nitrospira is the key organismof nitrite oxidation in engineered ecosystems like activated sludge orrecirculation aquaculture systems. Here, it has to compete for the substratewith Nitrotoga and Nitrobacter [1]. Members of Nitrospina and Nitrococcusare restricted to marine habitats and despite the aerobic nature ofnitrification, some NOB are also active under microaerophilic conditions.For example, a novel species of Nitrospina originated from the suboxic zoneof the Black Sea and the strain was co-isolated with an unknownheterotrophic gammaproteobacterium. Therefore, the whole physiologicalpotential of NOB and their interaction with accompanying bacteria remain tobe uncovered.[1] Alawi et al (2009): Environ. Microbiol. Reports 1, 184.EMP023Sequence Comparison and Gene Deletion of ThreeRedundant Oxygenase Subunits of (Chloro-) PhenolHydroxylases in Rhodococcus opacus 1CPJ.A.D. Gröning* 1 , D. Eulberg 2 , S.R. Kaschabek 1 , J.A.C. Archer 3 ,M. Schlömann 11 Group Environmental Microbiology, University of Mining and Technology,Freiberg, Germany2 NOXXON Pharma AG, Berlin, Germany3 Computational Bioscience Research Center, King Abdullah University ofScience and Technology, Thuwal, Saudi ArabiaRhodococcus opacus 1CP is a gram-positive bacterium and belongs to theclass of Actinobacteria. Strain 1CP has the ability to use a wide range of(chlorinated) aromatic compounds as sole energy and carbon sources.Phenol, 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, and 4-methylphenol are degraded via their corresponding catechols. These centralintermediates are then further catabolized by enzymes of the (modified)ortho-cleavage pathway which have been shown to differ significantly fromtheir counterparts in Proteobacteria.Three putative two-component phenol hydroxylases could be identified in R.opacus 1CP of which one (pheA(1)) was found to be located on themegaplasmid p1CP. All of them seem to play an active role in thedegradation of phenol as indicated by their expression pattern. However,protein purification proved to be extremely difficult due to a highly similarchromatographic behavior. Attempts were additionally hampered by a lowstability.Homologs of all of these phenol hydroxylases could also be found inRhodococcus jostii RHA1 by database comparison and it is remarkable thatthe RHA1-equivalent of pheA(1) is localized on pRHL1 and thus shows aplasmid location, too.To elucidate the catabolic functions of the three two-component phenolhydroxylases in R. opacus 1CP during the degradation ofchlorinated/methylated phenols the corresponding oxygenase subunits wereinactivated by gene knockout. In total seven mutants were generated andcharacterized by their growth parameters on phenol and methylphenol. Genedeletion was confirmed by DNA sequencing and by analyzing proteinexpression.EMP024Subtyping of F17- related genes in the wastewaterfrom small abattoirsS. Elmegerhi*Department of Micriobiology, Biotechnology Research Center, Tripoli,Libyan Arab JamahiriyaThe zoonotic pathogens of E.coli can survive over long periods in sewagesludge as well as on pasture land and in association water systems. Theycould be widely spread in the environment by direct land application ofsludge or by regular contamination of surface water, but limited informationis available concerning the spreading of these pathogens in sewage ofslaughterhouses. The F17 family includes F17a, F17b, F17c, F111 fimbriaeproduced by bovine E.coli strains , positive Escherichia coli isolates.A total of 88 wastewater samples were collected in wastewater treatmentplants at different stages of wastewater processing in small abattoirs, locatedin different regions in France, screened for the presence of F17 genes (F17a- A gene, F17 b- A gene, F17c-A/gafA gene and F111-A gene) bymultiplex PCR . F17 positive E. coli isolates were 47 samples , detection ofthe virulence factor F17 (F17 a- A gene, F17 b- A gene, F17c-A/gafA geneand F111-A gene) in the positive E. coli strains showed that the morefrequent genes are F17c-A/gafA gene and F111-A gene and the less frequentgene is F17 b- A gene . suggesting that they could be spread into theenvironment. Our results suggest that the diversity of the E. coli-associatedvirulence factors in the strains indicates that the environment may play animportant role in the emergence of new pathogenic E. coli strains and toincrease our knowledge of the important prevention needed in ourenvironment from the pathogenic E. coli and their mutual correlation.spektrum | Tagungsband 2011