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

groups. Multiple isolates were available for all major phylotypes. While 16SrRNA gene sequences were identical for the members of each 16S rRNAphylotype, the tree of the concatenated sequences of 9 housekeeping genesindicated a significant genomic divergence between the different strains.Based on the frequency of sequence divergence the isolatedSphingomonadaceae represent a clonal population. Based on its frequency,homologous recombination rather than mutation is the dominant forcedriving the divergence of the Sphingomonadaceae. Most significantly,MLSA revealed a distinct population substructure among individualphylotypes, suggesting different selection pressure between subclusters andthe existence of distinct evolutionary units despite the identical or verysimilar 16S rRNA gene sequences.Phenotypic clustering based on Biolog tests showed that the genotypicsubpopulations as detected by MLSA did not exhibit distinct substrateutilization patterns. Evidently, niche separation by adapation to differentgrowth substrates does not contribute towards genetic separation during theevolution of these freshwater Sphingomonadaceae.MDP013Spatial and temporal distribution of marine Bacteroidetessubgroups in contrasting water massesC. Bennke*, B. Fuchs, R. AmannDepartment of Molecular Ecology, Max Planck Institute for MarineMicrobiology, Bremen, GermanyMembers of the bacterial phylum Bacteroidetes are an important componentof marine picoplankton and play a key role in organic matter degradation. Inthis study we analysed the spatial and temporal distribution of marineBacteroidetes in samples taken during a cruise in September 2006 - from theArctic Circle towards the Azores alongside the 30° W meridian and insamples taken during the spring diatom bloom 2009 at the long-termecological research station Helgoland, Kabeltonne. Ten newly definedBacteroidetes subgroups were analysed by fluorescence in situ hybridisation(FISH) with specific oligonucleotide probes. Generally, members of thesubgroups affiliated to the class Flavobacteria were more abundant in alloceanic provinces examined than those belonging to the classesSphingobacteria and Cytophagia. In the North Atlantic Ocean thedistribution of several bacteroidetal subgroups indicated a specialisation forpolar, temperate or subtropical oceanic provinces. For example, one of thesubgroups affiliated to the DE2 clade occurred almost exclusively in thecold, nutrient-rich polar waters (DE2-805: 26.4 ± 1.0 x 10² cells ml -1 ),whereas another closely related subgroup was found preferentially in thewarm subtropical regions (DE2-873: 14.3 ± 1.7 x 10² cells ml -1 ). Similar tothe DE2-805 subgroup the Sphingobacteria A group was solely present inthe nutrient-rich polar waters. There, it was observed that they can survive inthe phycosphere of nanophytoplankton cells. During the spring diatombloom at Helgoland the same bacteroidetal clades were generally present athigher abundances (0.13-5.20%), than in the North Atlantic Ocean (0.01-0.37%). For example, the DE2-805 subgroup achieved abundances up to 5%in early April 2009; whereas, the DE2-873 subgroup reached abundances of0.19%. The Sphingobacteria clade SPC, which could not be detected in theNorth Atlantic Ocean showed abundances up to 0.13% during the Helgolandspring bloom. For most of the analysed Bacteroidetes clades distinctsuccession patters were revealed. Apparently, these subgroups possessdifferent spatial as well as temporal niches. We found hints that closelyrelated clades could represent different ecotypes with divergent lifestyles.MDP014Metalworking fluids reveal high unexpected diversemicrobial communitiesN. Lodders*, P. KämpferInstitute for Applied Microbiology, Justus-Liebig-University, Gießen,GermanyMetalworking fluids (MWF) are widely used in metalworking industries forcooling and lubrication during e.g. drilling, cutting and grinding. It isestimated that worldwide about 2 x 10 10 liters of MWF are used annually.Workers are exposed to MWF aerosols, which can cause health problemsand can lead to illnesses such as hypersensitivity pneumonitis or asthma.Several microorganisms have been detected in MWF, mainly Pseudomonasor Mycobacterium species, which could be causative agents for healthproblems. Additionally, representatives of genera such as Citrobacter,Ochrobactrum, Klebsiella, Neisseria and Salmonella could be identified. Sofar, the microbial diversity of in-use MWF was described as quite low. Onlyfew genera and species were found in each MWF sample.In order to analyse the microbial diversity more systematically, ten samplesof water based metal working fluids (MWF) were taken from five differentcompanies, where MWF are used as coolants and lubricants in machining.Analysis of colony forming units (CFU), total cell counts (TCC), isolation ofstrains, cultivation-independent analysis of clones and 16S rRNA genesequencing were carried out.The results show that the number of CFU ranges from 0 to 1.3 x 10 8 CFU /ml MWF emulsion (R2A medium, Oxoid LTD, England ), TCC were ashigh as 1.6 x 10 8 TCC / ml MWF emulsion. 37 strains from MWF wereisolated and their 16S rRNA genes were sequenced. Additionally, the 16SrRNA genes for 380 clones were sequenced (500 to 900 bp), and from 183clones the approximately full 16S rRNA genes were sequenced (1300 to1450 bp). A total of 56 different genera could be detected, the number ofdifferent genera within one MWF sample varied between 5 and 21. Of these56 genera, only 11 were detected by isolation and cultivation-independentmethods, 9 genera were detected only by isolation and 36 genera weredeteced only with cultivation-independent methods.It could be shown, that MWFs harbour a high, previously unknownmicrobial diversity. Dominating genera were e.g. Clostridium, Desemzia,Leucobacter, Pseudomonas, Serratia and Wautersiella. The usage time ofthe MWF (1 week to 23 months of use before sampling) does not seem tohave an impact on the microbial diversity within the MWF although mineraloil based MWF showed generally a higher diversity than MWF based onsynthetic oil.MDP015Diversity of nitrite-oxidizing bacteria in WWTPs:Selective enrichment of a novel lineage II Nitrospira in coculturewith NitrotogaB. Nowka* 1 , S. Off 1 , S. Lücker 2 , H. Daims 2 , E. Spieck 11 Department ofMicrobiology and Biotechnology, University of Hamburg,Hamburg, Germany2 Department of Microbial Ecology, University of Vienna, Vienna, AustriaIn wastewater treatment plants (WWTPs) the population structure of nitriteoxidizingbacteria (NOB) inhabiting activated sludge is complex. In mostWWTPs the genus Nitrospira represents the dominant NOB and twolineages have been found in this habitat yet. Until now only N. defluvii(lineage I) has been highly enriched from activated sludge but no Nitrospiraof lineage II. The only isolated representative of lineage II, N. moscoviensis,originates from a heating system and grows optimal at 39 °C. Other recentfindings demonstrate the presence of close relatives of the novel nitriteoxidizer Nitrotoga arctica - previously found in permafrost soil - inwastewater, where it coexists with Nitrospira. In consideration thatNitrotoga prefers low temperatures and low nitrite concentrations, andNitrospira has a broad temperature tolerance and favors also low nitriteconcentrations, the competition between these NOB has to be elucidated interms of changing conditions in WWTPs. For deeper insights into thephysiological differences between Nitrotoga and Nitrospira we performedvarious enrichments of these NOB. In this study we cultivated a novellineage II Nitrospira in co-culture with the previously discovered Nitrotogalikebacterium HAM-1 at 10 °C. First physiological experiments suggestedthat the novel Nitrospira of lineage II has lower growth temperature (about22 °C) and lower nitrite concentration preferences than N. defluvii, whichgrows optimal at a temperature of 32 °C. The culture was further studied bymarker gene phylogenies of 16S rRNA genes and genes coding for the betasubunit of the nitrite oxidoreductase (nxrB) as well as FISH probes forlineage-specific detection. Additionally, an increasing diversity ofNitrospira was detected by analyzing further enrichments and it was shownthat members of lineage I, which previously were found only in activatedsludge, are also present in different habitats like desert soils, archaic cavesystems and permafrost-affected soils. These results might help to explorephysiological differences of Nitrospira within the same 16S rRNA lineagefor a better understanding of the population dynamics in natural andengineered systems.spektrum | Tagungsband 2011