INCREASED METAL TOLERANCE BY THIOBACILLUS-FERROOXIDANS (SRCO) ISOLATED FROM AMBAMATA COMPLEX ORE MINE

Two isolates of T. ferrooxidans (SRco) cultures 1 and 2 have been developed to tolerate Cd2+, Co2+, Cu2+ and Ni2+ in different conditions. Cadmium, in the form of cadmium sulphate, has been found to be most tolerated by the organisms, followed by copper, nickel and cobalt in the form of sulphate salts. Ni2+ and Co2+ are tolerated equally by the organisms, but organisms needed more time to oxidize 95% Fe2+ --> Fe3+ in presence of Co2+ as compared to Ni2+. Cu2+ is found to be most inhibitory even at low concentrations while Co2+ shows inhibitory action at higher concentration. Isolates have been developed to tolerate as high as (and show 95% iron oxidation) 1.75, 1.527, 1.254 and 1.254% (correspond to 16, 24, 21, 21 mM) cadmium, copper, nickel and cobalt, respectively.