Uptake of cadmium by marine bacteria

Abstract

THE UPTAKE of metals by microorganisms has been well established (TORNABENE and EDWARDS, 1972; COPd'E, 1975; BEVERIDGE and KOVAL, 1981). In the case of cadmium, the metal content of bacterial cells could reach 40% of the dry weight (MACASKIE, DEAN, CHEETHAM, JAKEMAN and SKARNULIS, 1987). The transport of cadmium was investigated in Staphylococcus aureus (TYNECKA, GOS and ZAJAC_., 1981a,b) and Bacillus subtilis (LAD. DAGA, BESSEN and SILVER, 1985) and has been demonstrated to occur via the energy dependent manganese transport system. LADDAGA and SILVER (1985) have shown that the accumulation of cadmium was also energy dependent in Escherichia coil In some cases, a lower cadmium uptake could be linked to the higher resistance of the strain to cadmium. This has been shown for Staphylococcus aureus (TYNECKA, GOS and ZAJAC, 1981a; WlTrE, GREEN, MISRA and SILVER, 1986) and Bacillus subtilis (LADDAGA, BESSEN and SILVER, 1985; MAHLER, LEVINSON, WANG and HALVORSON, 1986). This resistance could be either a chromosomal (LADDAGA, BESSEN and SILVER, 1985; BURKE and PFISTER, 1986) or a plasmid encoded characteristic (TYNECKA, GOS and ZAJAC, 1981a,b; HoRrrsu, YAMAMOTO, WACHI, KAWAI and FUKUCHL 1986). The uptake of cadmium, transport through the cell membranes, toxic effects and the mechanisms of detoxification have been described for Gram positive and Gram negative bacteria, but little has yet been done on marine (i.e., sodium dependent) bacteria. The purpose of this paper is to describe the uptake of cadmium by marine bacteria in relation to their metabolic activity and their resistance to this metal.