Physical enrichment and physiological activities of bacterial candidate division OP3
Wang, J. (2010). Physical enrichment and physiological activities of bacterial candidate division OP3. MSc Thesis. Erasmus Mundus Master of Science in Marine Biodiversity and Conservation (EMBC): Bremen. 55 pp.
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Document type: Dissertation
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| Abstract |
A limonene-degrading, methanogenic enrichment was formerly characterized and cells belonging to the bacterial candidate division OP3 were found in the clone library as well as in CARD-FISH studies. In this study, molecular approaches were confirmed to specifically target OP3 cells including PCR, mono-labeled FISH and CARD-FISH, and the enrichment community structure was quantified by CARD-FISH. An anaerobic density gradient centrifugation protocol was established based on Percoll, and a partition was enriched in OP3 cells to 89% from 21% in the enrichment culture. The physiological potentials were studied from both enrichment and partitions, acetate formation was observed from limonene, formate (lysed first to hydrogen and CO2), hydrogen and CO2. Methanogenesis was found to happen from acetate, or hydrogen plus CO2. The differences of those reactions in the partitions enabled an algebraic model that solved the physiology of each group, based on the quantitative determination of maximum turnover rate of hydrogen, formate and acetate. The model solution showed that OP3 group cells were most likely carrying out acetogenesis based on hydrogen and CO2, but also possessed the ability of lysing formate to hydrogen and CO2. The other groups physiological potentials yielded a better understanding of the limonene degradation and methanogenesis process: Deltaproteobacteria and Syntrophomonas degraded limonene to acetate, possibly also to hydrogen and formate; Syntrophomonas and OP3 were able to convert hydrogen to acetate, OP3 lysed formate to hydrogen and Bacteriodetes were able to reverse this reaction, and Deltaproteobacteria converted formate to acetate; hydrogen and CO2 as well as acetate were utilized by Archaea to produce methane. Further studies will attempt to isolate OP3 cells in order to understand the limonene degrading syntrophic community, and to explore genomic information for evidence for acetogenesis of OP3. |
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