International Journal of Chemical Engineering Research

We successfully isolated two novel gram-negative aerobic chemolithotrophic sulfur-oxidizing bacterium, designated strain NICI1 and strain NICI2, from mine ores growing under acidophilic conditions. Strain NICI2 oxidized elemental sulfur, thiosulfate, and sulfide to sulfate under oxic conditions and cause to reduce pH. Strain NICI1 was able to oxidize the Fe⁺⁺ to Fe⁺⁺⁺. The rate of oxidation of elemental iron and sulfur from NICI1and NICI2 were higher than those of Thiobacillus ferrooxidans DSM583 and Acidithiobacillus thiooxidans DSM622 as standard strains respedtively. Further isolation 16S23S rRNA intergenic spacer gene sequence analysis revealed that newly isolated strains NICI1 and NICI2 were affiliated with members of the genus Acidithiobacillus. These results demonstrated that NICI1 was Acidithiobacillus ferrooxidans and NICI2 was Acidithiobacillus thiooxidans (Genbank accession number of 16S-23S intergenic spacer rRNA gene fragment of NICI1 and NICI2 are AM404268 and AM404265 respectively). NICI1 and NICI2 were capable to extract the copper. Therefore the amount of copper extraction of these bacteria were measured in shaking flasks and showed that the efficiency of copper extraction in these bacteria were higher than standard strains. According to results obtained from this study, the newly indigenous NICI1 and NICI2 can be a promising candidate for industrial application in copper extraction (Bioleaching).