hide
Free keywords:
anaerobic methane oxidation; geomicrobiology; subsurface microbiology; sulfate-methane transition zone
Abstract:
The microbial diversity of sulfate-reducingand methanogenic subsurface sediments of theBenguela Upwelling System was analyzed using 16SrRNA gene-directed molecular methods. Communitiesmediating anaerobic oxidation of methane (AOM) in thesulfate-methane transition zone (SMTZ) were also tar-geted. Denaturing gradient gel electrophoresis (DGGE)of DNA extracted from sediment samples showed thepresence of complex bacterial communities in the sedi-ment zones above and below the SMTZ, whereas only 3DGGE-defined populations were detected in theSMTZ. Sequencing of excised DNA fragments revealedthe presence of bacterial populations related to sulfate-reducing bacteria (SRB) and those distantly related tothe Haloanaerobiumphylum. One of the populationsdetected at the SMTZ was closely related to SRB and tobacterial populations detected at mud volcanoes in theBlack Sea. Comparative analysis of sequences from aclone library made with genomic DNA from the SMTZand primers specific for archaeal 16S rRNA genes re-vealed members of 5 different lineages, including un-usual crenarchaeal ribosomal RNA sequences. None ofthe archaeal sequences, however, was related to groupspreviously implicated in anaerobic methane oxidation.
