关键词: 嗜酸性氧化亚铁硫杆菌, 亚铁氧化酶基因, 热稳定性

Abstract: Acidithiobacillus ferrooxidans is an important mineral-bioleaching bacterium with ferrous ion or reducible sulfide as the energy substance. Ferrous oxidase plays a key role in the ferrous ion oxidation process. In this study, four strains (YHC, 721, 737 and 745) were isolated from different mines showed more than 98% nucleotide sequence with the 16S rDNA of A. ferrooxidans. Ferrous oxidase activity assays indicated that strains YHC and 737 had similar activity, which were obviously higher than that of strains 721 and 745. Four ferrous oxidase-encoding genes from these Acidithiobacillus strains were amplified by PCR, sequenced and compared with reference sequences in GenBank. Three bases showed difference and accounted for the only divergence at position 73, Val for strains YHC and 737 and Ala for strains 721 and 745. When substituted Val with Ala by using the site-directed mutagenesis, the mutant enzymes showed decreased thermostability and shorter half-life. As results, the ferrous oxidase had reduced functional duration and less enzyme activity.

Key words: Acidithiobacillus ferrooxidans, ferrous oxidase gene, heat stability