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

tetracycline, sulfonamide and fluoroquinolone families, which are known tobe avidly applied in animal husbandry [4]. Known antibiotic resistancegenes will be monitored via quantitative real-time-PCR on transcriptional aswell as genomic levels to illuminate changes and the persistence ofresistance activity driven by the selective pressure of antibiotics present. Atthe same time 16s rDNA-based sequence analysis of manure samples arepreformed to examine microbial diversity changes. Preliminary resultsreveal variations in the biodiversity patterns of manure samples, with asignificant increase (30%) of species distribution in samples withundetectable antibiotic concentrations indicating that antibiotic levels foundin conventionally treated manure may have severe ecological consequences.Furthermore, pathogenic activity shows an invariable level of 72 % of thetotal biodiversity, independent of antibiotic-concentration. This approachwill generate an insight into the persistence of ARGs and thus allowingmanure-utilisation without the distribution of resistant strains that threatenhuman health and ecological diversity.[1] Baquero, F. et al (2008): Antibiotics and antibiotic resistance in water environments. CurrentOpinion in Biotechnology 19(3): 260-265.[2] Chee-Sanford, J. C. et al (2009): Fate and Transport of Antibiotic Residues and AntibioticResistance Genes following Land Application of Manure Waste. Journal of Environmental Quality38(3): 1086-1108.[3] Martinez, J. L. (2009): Environmental pollution by antibiotics and by antibiotic resistancedeterminants. Environmental Pollution 157(11): 2893-2902.[4] Renew, J. E. and C. H. Huang (2004): Simultaneous determination of fluoroquinolone,sulfonamide, and trimethoprim antibiotics in wastewater using tandem solid phase extraction andliquid chromatography-electrospray mass spectrometry. Journal of Chromatography A 1042(1-2):113-121.EMP116Will not be presented!EMP117Agricultural Soil Protists Assimilate Carbon fromSupplemental 13 C-CelluloseS. Schellenberger, A. Chatzinotas, V. Jaschik, D. Schlosser, H.L. Drake,S. Kolb*Department of Ecological Microbiology, University of Bayreuth, Bayreuth,GermanySoil prokaryotes are degraders of cellulose in aerated agricultural soils.Certain soil micro eukaryotes (i.e., fungi and protists) may (a) utilizecellulose and its degradation products or (b) graze on cellulose-degradingbacteria. In a preceding study, agricultural soil slurries were supplementedwith 13 C-cellulose or 12 C-cellulose (control). Dissimilation under oxicconditions yielded carbon dioxide, whereas mixed acid and butyratefermentations and ferric iron reduction were important anaerobic processesunder anoxic conditions. Actinomycetes, Planctomycetes, and a novelfamily-level taxon within the Bacteroidetes were primary consumers underoxic conditions as determined by 16S rRNA-based stable isotope probing(rRNA SIP). In contrast, Clostridiaceae and novel family-level taxa ofBacteroidetes and Actinobacteria were primary consumers under anoxicconditions. In the current study, 13 C-labeled protists were analyzed andassessed by (a) terminal fragment length polymorphism (TRFLP) analysesand (b) generating gene libraries of 18S rRNA genes using primers specificfor Eukaryotes, Chrysophyceae (Heterokontophyta), and Kinetoplastea(Kinetoplastida). Labeled OTUs were detected in oxic treatments, whereaslabeling was not apparent in anoxic treatments. Assimiliation of 13 C by soilprotists might suggest that grazing on cellulose-degrading bacteria was animportant pathway of carbon assimilation from cellulose into soil protistancommunity. However, it is unknown if detritivory or also osmotrophy, i.e.direct assimilation of cellulose and breakdown products, were protistanfeeding strategies.EMP118Reductive Dechlorination of Chlorinated Benzenes inAnaerobic Enrichment Cultures from Vietnam andGermanyD. Hoa Tran*, L. AdrianDepartment of Isotope Biogeochemistry, Helmholtz Center forEnvironmental Research (UFZ), Leipzig, GermanyChlorinated benzenes are important industrial intermediates and solvents.The intentional or accidental release causes significant concern due to thetoxicity and persistence. Among the chlorobenzenes, hexachlorobenzene(HCB) is the most persistent environmental pollutant and is listed as one ofthe 12 persistent organic pollutants in the Stockholm Convention. A secondcongener of high concern is 1,3,5-TCB which has been described as theproduct of HCB degradation under anaerobic conditions and is persistentunder aerobic and anaerobic conditions. Only marginal information isavailable on the degradation of 1,3,5-TCB by anaerobic mixed cultures.Using inocula from sediments, soils or water originating from differentlocations in both Vietnam and Germany we obtained mixed culturesdechlorinating trichlorobenzenes (TCBs) (1,2,4-TCB, 1,2,3-TCB and 1,3,5-TCBs) and HCB. HCB was reductively dechlorinated topentachlorobenzene, which was transformed to a mixture of 1,2,3,5- and1,2,4,5-tetrachlorobenzenes. The final end-products from HCB were 1,3,5-TCB, 1,3-dichlorobenzene (DCB), 1,4-DCB and monochlorobenzene(MCB). The experiments were repeated with TCBs (1,2,4- and 1,2,3-TCB)and the final end-products of these TCBs were 1,3-DCB, 1,4-DCB andmonochlorobenzene. Besides, also 1,2-DCB was produced from TCBs. Inthe pathway producing 1,3,5-TCB from HCB, only doubly flanked chlorinesubstituents were removed while in the pathway leading to 1,2-DCB, 1,3-DCB, 1,4-DCB and MCB from HCB and TCBs both doubly and singlyflanked chlorine substituents were removed. We are now maintaining thesedechlorination pattern and try to link dechlorination pathways with singlepopulations in the mixed consortia. Isolation of bacteria that remove singlyflanked chlorine substituents is essential to further understand thebiochemical reasons for the reaction specificity of different enzymes.Hölscher et al. 2010, Environ. Sci. Technol. 44: 8936-8942EMP119Investigation of biosynthesis, function and significance ofsiderophores in Phaeobacter gallaeciensisP. Beyersmann*, M. Berger, S. Thole, M. Simon, T. BrinkhoffInstitute for Chemistry and Biology of the Marine Environment (ICBM),Carl von Ossietzky University, Oldenburg, GermanyBecause of the very low solubility of Fe 3+ in the sea, iron is a limiting factorfor microorganisms, not only for phytoplankton and cyanobacteria, but alsofor heterotrophic bacteria. To be able to compete for iron, some bacteriaproduce siderophores, which are strong soluble Fe 3+ chelating ligands. Therole of siderophores is to scavenge iron from the environment and make themineral available to the cell. Representatives of the Roseobacter group(Alphaproteobacteria) are very successful in many marine habitats and showa high metabolic versatility, however, production of siderophores has notbeen reported yet for Roseobacters. In the genome of Phaeobactergallaeciensis, a representative of the Roseobacter group, we found genescoding for a putative iron-siderophore uptake system. Production ofsiderophores by P. gallaeciensis was subsequently confirmed by a chromeazurol S (CAS) assay. Construction of knock out mutants to study geneticand regulatory aspects of the siderophore biosynthesis in P. gallaeciensis isin progress. On the one hand we focus on the investigation of thebiosynthetic pathway, on the other hand we characterize the function andimportance of the siderophore for the organism. Furthermore, Phaeobactergallaeciensis produces acylated homoserine lactones (AHLs), a class ofsignalling molecules involved in bacterial quorum sensing. Quorum sensingsystems were also reported to have influence on siderophore production. Tostudy a possible correlation, we constructed an AHL-deficient mutant inorder to compare the expression of genes involved in siderophore productionin the wild-type and the mutant strain.EMP121Detection of specific epibacterial communities affiliatedto the marine Roseobacter group reflects adaptation tovarious macroalgaeM. Dogs*, T. Brinkhoff, M. SimonInstitute for Chemistry and Biology of the Marine Environment (ICBM),Carl von Ossietzky University, Oldenburg, GermanyBacteria of the Roseobacter clade are abundant and widely spread in manymarine ecosystems and were also detected on various macroalgae. Marinemacroalgae are known to be covered by a dense microbial biofilm with avariety of different species. The microbial communities are specific for eachalgal species. In order to investigate whether organisms of the Roseobacterclade are present on many different macroalgae, we sampled a variety ofspektrum | Tagungsband 2011