Cadmium, nickel and vanadium accumulation by three strains of marine bacteria

ABSTRACT

Three marine bacteria, Pseudomonas putida PTCC 1664, Bacillus cereus PTTC 1665 and Pseudomonas pseudoalkaligenes PTCC 1666 isolated from the East Anzali wetland sediments of the Caspian Sea, were resistant to heavy metals of Cadmium [Cd], Nickel [Ni] and Vanadium [V]. Pseudomonas pseudoalkaligenes PTCC 1666 was found to be resistant to all 3 metals Ni, Cd, V. Heavy metal uptake was determined in both the biomass and supernatant by the Atomic Absorption Spectrophotometer [AAS]. These bacteria showed enhanced absorption and growth in the presence of Cd and Ni at 80-100 mg/l and V at 40 mg/l concentrations. The high uptake of Cd, Ni and V was directly proportional to their respective concentrations, 5-100 mg/l for Cd and Ni and 5 - 40 mg/l for V. The maximum amount of heavy metal uptake occurred during stationary phase when cells were incubated at 30[degree]C for 72h. The results revealed that these bacteria accumulated approximately 40-50% Cd, 5-6% Ni and 10-12% V. Bacterial cells Immobilized in alginate gel showed more efficiency in biosorbing heavy metals than free cells [80%]. Scanning Electron Microscopy [SEM] results indicated that the marine bacteria were capable of accumulating several metals, showing that the isolated bacterial strains can be used as potential candidates for bioremediation, with respect to Cd, Ni and V removal from aqueous effluents