Characterization by denaturing gradient gel electrophoresis of bacterial communities in deep groundwater at the Kamaishi Mine, Japan

Bacterial communities in groundwater collected from five different sites at the Kamaishi Mine were investigated by using denaturing gradient gel elect rophoresis (DGGE). The bacterial cells in groundwater were collected on Mil lipore filters, and their nucleic acid was extracted by freeze-thaw cycles. A partial 16S rRNA gene was amplified by using a universal primer set by P CR. The PCR products were analyzed by DGGE. The band pattern of DGGE was es sentially identical between two samples obtained from different depths in t he same borehole (KH-1). Samples from the other sites differed from one ano ther. The partial sequences of 16S rRNA genes (about 350 base pairs) isolat ed from bands were determined and analyzed for phylogenetic position. Almos t half the sequences from two samples of the KH-1 belonged to the cluster o f spore-forming, gram-positive sulfate reducer, Desulfotomaculum. The other bands also were related to those of obligate anaerobes. This suggests that the environment in both sites of KH-1 was highly anaerobic. Although only a few sequences were retrieved from the other sites, they were phylogenetic ally distanced from known isolates.