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Recent investigations on the microbial ecology of oil reservoirs in a variety of locales indicated that these habitats harbor various assemblages. In this study, a cultured-independent molecular technique, Terminal Restriction Fragment Length Polymorphism (T-RFLP), was used to analyze the microbial diversity of an injection well (S12-ZHU) and three related production wells (S12-4, S12-5 and S12-19) in the ShengLi oilfield (Shandong province, China). The 16S rRNA genes were amplified by PCR with the 5'carboxy-fluorescein (5-FAM)-labelled universal forward primers (27F for bacteria and 21F for archaea) and a universal reverse primer (1495R). Then the 16S rRNA genes were digested with restriction enzymes (Hae III and Hha I) and analyzed by using an automated DNA sequencer. The Shannon-Wiener Diversity index, based on the T-RFLP profiles, indicated that the bacterial and archaeal species richness in the injection well was higher than those of the production ones. The similarity coefficient showed the microbial community similarity among the four samples was 22.4%-30.8% (Bacteria) and 20.8%-34.5% (Archaea), respectively. According to the analysis by TAP T-RFLP program, species belonging to Pseudomonas, Marinobacter and Methanosarcina as well as some uncultured archaeon were supposed to be the dominant bacteria in all four samples. Thus, this study indicates that T-RFLP is useful for analysis of the microbial diversity in petroleum reservoirs.

The aims of this work were to explore the diversity of halophilic archaea in hypersaline lakes of Inner Mongolia, China and to collect novel halophilic archaea. One hundred and sixty-five halophilic archaea were isolated from the three different types of hypersaline lakes (Erliannor, shangmatala and Xilin soda lake) in Inner Mongolia. By analysis of the restriction patterns of amplified 16S rDNA (ARDRA) with the enzyme Afa I and Hae II, respectively, the isolates were clustered into 14 genotypes, and the representatives of each genotype were randomly chosen for the determination of 16S rDNA sequence. The phylogenetic analysis revealed that all of the isolates were clustered into 10 groups: Halorubrum, Natronococcus, Natronorubrum, Haloterrigena, Halorhabdus, Halobiforma, Haloarcula, Haloferax and other two unknown groups. Dominant isolates were related to Halorubrum spp. in all three lakes. Some of the isolates studied showed less affiliation with known taxa ( <98% sequence similarity) and may represent novel taxa. Two isolates HXH33 and HSH33 showed very less affiliation with known genus ( < 93% sequence similarity) and may represent two new genera. These results suggest that diverse archaea exist in and the unknown archaea thrive in the hypersaline lakes of Inner Mongolia.

The environmental DNA was directly extracted from the sediment in Parece Vela Basin, Pacific Ocean, at a depth of 5010 m. Bacterial 16S rRNA gene library of 32 clones was generated using bacterial universal primers and 16S rDNA sequences were analyzed phylogenetically. 17 phylotypes were obtained. The library was dominated by gamma-Proteobacteria, alpha-Proteobacteria and marine uncultured bacteria. Sixty-two percent of the cloned sequences was highly related to the known bacteria in the genus Halomonas, Alcanivorax, Pseudomonas, Acinetobacter, Pseudoalteromonas (> 96% sequence similarity), while some of the cloned sequences showed less affiliation with known taxa (< 94% sequence similarity) and may represent novel taxa.

An alkaliphilic and slightly halophilic Gram-positive rod, designated strain F10, was isolated from Haoji soda lake in Inner Mongolia Autonomous Region, China. Strain F10 grew optimally in the presence of 3% (W/V) NaCl, pH 9.5 and 37 degrees C. It was facultatively anaerobic, motile with peritrichous flagella, sporulating, catalase- negative. The (G + C) content of the DNA was 40 mol%. The cell wall contained meso-DAP. Phylogenetic analyses based on 16S rDNA sequences comparisons indicate that strain F10 was a member of the genus Amphibacillus. DNA-DNA similarity of less than 30% with the described species of Amphibacillus supported the view that this organism represented a new species of the genus Amphibacillus. The name Amphibacillus haojiensis sp. nov. is proposed.