Isolation and selection of sulfur-oxidizing bacteria for the treatment of sulfur-containing hazardous wastes

A total of 75 microorganisms were obtained from high-sulfur content environmental samples using different sulfur sources. Fifty-four of them had the ability to oxidize sulfur at 1% (w/v) in liquid culture, however only three of them AZCT-M125-5, AZCT-M125-6, and AZCT-M125-7 were able to grow autotrophycally using elemental sulfur at concentrations higher than 1 % and up to 9 % (w/v) as energy source. They produce more than 300 mg sulfate/L. Also, these microbial cultures were able to produce sulfate within pH 3 to 7. Analysis based on 16S rRNA gene sequences indicated that microbial cultures AZCT-M125-5 and AZCT-M125-6 were closely related to Acidithiobacillus thiooxidans while identification of AZCT-M125-7 was not possible. According to the results, these three microorganisms can be excellent candidates for the future development of alternative biotechnological processes for the treatment of hazardous wastes containing sulfur.