CHARACTERIZATION OF 16S RIBOSOMAL-RNA GENES FROM OIL-FIELD MICROBIAL COMMUNITIES INDICATES THE PRESENCE OF A VARIETY OF SULFATE-REDUCING, FERMENTATIVE, AND SULFIDE-OXIDIZING BACTERIA

Oil field bacteria were characterized by cloning and sequencing of PCR -amplified 165 rRNA genes, A variety of gram-negative, sulfate-reducin g bacteria was detected (16 members of the family Desulfovibrionaceae and 8 members of the family Desulfobacteriaceae). In contrast, a much more limited number of anaerobic, fermentative, or acetogenic bacteria was found (one Clostridium sp,, one Eubacterium sp,, and one Synergis tes sp,). Potential sulfide oxidizers and/or microaerophiles (Thiomicr ospira, Arcobacter, Campylobacter, and Oceanospirillum spp.) were also detected. The first two were prominently amplified from uncultured pr oduction water DNA and represented 28 and 47% of all clones, respectiv ely. Growth on media containing sulfide as the electron donor and nitr ate as the electron acceptor and designed for the isolation of Thiomic rospira spp, gave only significant enrichment of the Campylobacter sp, , which was shown to be present in different western Canadian oil fiel ds, This newly discovered sulfide oxidizer may provide a vital link in the oil field sulfur cycle by reoxidizing sulfide formed by microbial sulfate or sulfur reduction.