Construction of Recombinant Bioleaching Bacteria Thiobacillus ferrooxidans with Fluoride-Resistant Activity

Thiobacillus ferrooxidans is an important bioleaching bacterium, widely used in leaching, recovery of low-grade metals and environmental bioremediation. In bio-metallurgy industry, fluoride existing in some hard rock uranium deposits in south China severely affects the bacteria viability and inhibit leaching reproduction. In this study, the flr-4 gene that has strong resistance to fluorine ion in Caenorhabditis elegans, was cloned into pET30a vector and expressed in E. coli BL21. the ability of fluoride resistance in E. coli was increased obviously. To increase the fluoride-resistance of bioleaching bacterium T. ferrooxidans strain 1 (T.f1), the flr-4 shuttle recombinant plasmid pJRD215-flr-4 was constructed and transferred into T.f1 by conjugation. pJRD215-flr-4 was stable in T.f1 with more than 70% retention after 50 generations. Recombinant T.f1 was tolerant to fluorine ions and grew well under fluoride (F^-) stress especially at F^- concentrations ranging from 10 mg/L to 60 mg/L.