Screening, identification and sulfide oxidation characteristics of a haloalkaliphilic sulfur oxidizing bacterium

Abstract:

[Background] Biogas and natural gas often contain a certain amount of hydrogen sulfide. Hydrogen sulfide is not only polluting the environment but is also harmful to humans. [Objective] In this study, a sulfur-oxidizing bacterium was screened from sodium alkali lake sediments in the Badain Jaran Desert using sodium thiosulfate as the sole energy source, and its sulfur oxidation properties were studied. [Methods] Strain BDL05 was identified by a variety of methods including Gram staining, colony morpholog, and 16S rRNA gene sequence analysis. [Results] Strain BDL05 was a Gram-negative bacterium, helical, belonging to the family of Ectothiorhodospiraceae and Thiomicrospira genus. The 16S rRNA gene sequence similarity of BDL05 to Thiomicrospira microaerophila ASL 8-2 reached 99.8%, so it was named as Thiomicrospira microscopila BDL05. The optimum pH for sodium thiosulfate was 9.3, and the optimum total sodium salt concentration was 0.8 mol/L. It had a strong ability to oxidize sodium sulfide. In the airlift reactor using sodium sulfide as the sulfur source, the yield of elemental sulfur was 94.7%, and the production rate was 3.0 mmol/(L·h). [Conclusion] This indicated that Thiomicrospira microaerophila BDL05 was a sulfur oxidizing bacteria which can be of a strong applicability in gas biological desulfurization.

Key words:Biological desulfurization, sulfur oxidizing bacteria, halophilic alkalophilic