Methanogens play important roles in the cycling processes of organic carbon, giving methane as the final product. In Vietnam, anaerobic technologies such as biogas, UASB (upflow anaerobic sludge blanket) or AF (anaerobic filter) have been applied effectively under freshwater condition, however cannot be succesfull under brackish and seawater conditions due to low activity of microbial groups incuding methanogens. In order to support anaerobic technologies under salted water conditions, in the present study effective methanogen sources were eshtablished via enrichment and isolation of pure cultures from marine sediment samples in Vietnam. Four active methanogenic consortia were obtained via enrichment procedure using marine sediment samples collected from Nhatrang and Catba with acetate or methanol as organic substrates. The enrichments were carried out in brackish water and seawater environments. PCR-DGGE analyses of the 16S rDNA gene showed that the acetate-feeded enrichment cultures were dominated by Methanosarcina species, whereas the methanol-feeded enrichment cultures were dominated by Methan percentbus species. In total, tern methanogenic strains were isolated from these consortia. Based on the PCR-DGGE analyses of the 16S rDNA gene they could be arranged into three groups, the representative strain of each 21, 23a, and 25a showed the highest identities ( or = 96 percent) of the 16S rDNA gene with Methanosarcina semeisiae, Methanolotbus profundi and Methanosarcina vacuolata. respectively. These strains represented the first methanogenes isolated from marine environment in Vietnam.
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20,970,682
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