Isolation and identification of a thermophilic anaerobic bacterium

Abstract:

Abstract: [Objective] To find new microbial resources from a high-temperature oil reservoir.[Methods] Strain HL-3 was isolated by Hungate Anaerobic Technique from oil reservoir water sampled from Dagang oilfield, China. Through physiological, biochemical and phylogenetic analysis, the strain HL-3 was classified. [Results] Cells were Gram-positive. The temperature range for growth was 40℃－75℃ (optimum at 60℃) and the pH range was 5.0－8.0 (optimum at 6.5). The isolate could grow in the presence of 0%-3.2% NaCl (optimum at 0.25% ). Glucose, ribose, mannose, xylose and cellobiose could be metabolized. Metabolites of glucose were ethanol, acetate, CO2 and trace amount of propionate and butanol. The G+C content of DNA was 33.9mol%. Based on 16S rRNA studies，strain HL-3 was most close to T. uzonensis DSM 18761T(EF530067) with 98.8% similarity and to T. sulfurigignens DSM 17917T (AF234164) with the 98.1% similarity. Strain HL-3 tolerated to high sulfite (0.1mol/L) ions and extremely high concentration of thiosulfate (0.8 mol/L). When the concentration of thiosulfate was higher than 0.075 mol/L, the cell would generate S element granular. The presence of H2S gas was detected inside of space at the top of serum bottle. Strain HL-3 together with T. uzonensis DSM 18761T differed greatly in toleration of thiosulfate and sulfite. The toleration of strain HL-3 to thiosulfate and sulfite was most close to T. sulfurigignens DSM 17917T (AF234164). In addition, strain HL-3 to metabolite thiosulfate and sulfite was also similar with T. sulfurigignens DSM 17917T (AF234164). However, it differs largely from both of them to metabolize glucose.[Conclusion] Therefore, strain HL-3 may be a new spieces of the Thermoanaerobacter, and the definitive classification positioning is still awaiting for further verified with the method of determination of whole-genome DNA–DNA similarity[1].