INFLUENCE OF PRESERVATION SUBSTRATE ON IRON OXIDATION ABILITY OF VARIOUS THIOBACILLUS-FERROOXIDANS ISOLATES

Iron oxidation abilities of 11 isolates were compared after their pres ervation on ferrous sulphate and polymetallic sulfide concentrate cont aining 2.5 g l(-1) Cu and 45 g l(-1) Zn respectively in the leached so lution. The fastest growing cultures, Tf CD-2, grown on ferrous substr ate showed the shortest iron oxidation period of 35 h as compared to 4 7 h by Tf LIG preserved on polymetallic concentrate for six months und er ambient conditions, for > 95% iron oxidation. All the isolates exce pt Tf LIG showed reduction in iron oxidation rate from 16.8 to 125.4 m g l(-1) h(-1) while Tf LIG showed an increase of 44.5 mg l(-1) h(-1) i n iron oxidation rate when grown on polymetallic concentrate. Pattern of iron oxidation varied with each isolate when preserved on either of the substrates. Considering the pattern and overall iron oxidation ra te, Tf CD-2 and Tf HW-1 could be the isolates of choice due to highest iron oxidation rate exponentially exhibited even after 75% of substra te was utilised.