THIOBACILLUS FERROOXIDANS FOR ENHANCED METAL LEACHING CAPABILITIES.

THIOBACILLUS FERROOXIDANS CATALYZES IRON (II) OXIDATION AND HEAVY METAL LEACHING FROM LOW GRADE ORES BY A COMPLEX PROCESS. BIOLOGICAL LEACHING IS A COMPOSITE OF DIRECT OXIDATION OF METALS BY THE ORGANISM AND THE OXIDIZING ACTIVITY OF FE3+ PRODUCED BY BIOLOGICAL OXIDATION OF FESO4. THE BLUE COPPER PROTEIN, RUSTICYANIN, IS THOUGHT TO BE THE INITIAL ACCEPTOR OF ELECTRONS FROM FE2+ (COX & BOXER, 1978; COX ET AL., 1978; INGLEDEW, 1982; INGLEDEW ET AL., 1977; 1978) AND OTHER METALS (DISPIRITO & TUOVIENEN, 1982; 1984). THIS PROTEIN IS, THEREFORE, A KEY INTERMEDIATE IN METAL OXIDATION AND LEACHING. COX & BOXER (UNPUBLISHED) HAVE ALSOOBTAINED EVIDENCE THAT RUSTICYANIN CATALYZES THE RATE LIMITING STEP IN METAL OXIDATION BY T.FERROOXIDANS. WE HOPE TO DEOMONSTRATE THE FEASIBILITY OF A MOLECULAR BIOLOGICAL APPROACH TO CLONING THE GENE ENCODING RUSTICYANIN. THIS REQUIRES DEVELOPMENT OF GENETIC TRANSFORMATION AND CLONING SYSTEMS IN T.FERROOXIDANS, AND A METHOD FOR SELECTING REUSTICYANIN-DEFICIENT MUTANTS. IN PARALLEL, WE WILL (I) TRANSFER ANTIBIOTIC RESISTANCE TO THE ORGANISM BY A METHOD DESCRIBED FOR OTHER THIOBACILLI (DAVIDSON & SUMMERS, 1983; HOLMES ET AL., 1983; KULPA ET AL., 1983) (IN ORDER TO UNDERSTAND TRANSFORMATION AND CLONING IN T.FERROOXIDANS), AND (II) DETERMINE THE FEASIBILITY OF SELECTING RUSTICYANIN-DEFICIENT MUTANTS. COMMERCIAL APPLICATIONS LIE IN THE ABILITY TO CONSTRUCT A SYSTEM FOR LEACHING HIGH VALUE AND STRATEGICALLY IMPORTANT METALS FROM LOW GRADE ORES THAT WOULD OTHERWISE BE ECONOMICALLY UNWORKABLE.