Bacteriology of manganese nodules. VI. Fate of copper, nickel, cobalt, and iron during bacterial and chemical reduction of the manganese (IV)

Abstract

Copper, nickel, and cobalt entered into seawater solution while the manganese (IV) oxide matrix of marine ferromanganese nodules to which they were bound was being reduced by glucose in the presence of peptone. Negligible amounts of iron were solubilized under similar conditions. Bacillus GJ 33 significantly accelerated the reduction and solubilization of manganese (IV) oxide by chemical means and thereby also accelerated the solubilization of nickel and cobalt, and, in advanced stages, of copper. Nickel and cobalt solubilization were directly dependent on manganese (IV) oxide reduction and solubilization while copper solubilization was only partly dependent on it. Some copper in the ferromanganese nodule substance was solubilized as a result of complexing by peptone without concurrent manganese (IV) oxide reduction. The release of manganese, copper, or nickel (cobalt was not tested) could not be attributed to acid formation during glucose oxidation by manganese (IV) oxide regardless of whether the reaction was purely chemical or catalyzed by bacteria. These findings suggest that nickel and cobalt are more tightly bound to the manganese (IV) oxide matrix than copper. An adsorption experiment showed that manganese, copper and nickel could originally have entered the nodule matrix by adsorption.