BACTERIAL REDUCTION OF CHROMIUM

A mixed culture was enriched from surface soil obtained from an easter n United States site highly contaminated with chromate. Growth of the culture was inhibited by a chromium concentration of 12 mg/L. Another mixed culture was enriched from subsurface soil obtained from the Hanf ord reservation, at the fringe of a chromate plume. The enrichment med ium was minimal salts solution augmented with acetate as the carbon so urce, nitrate as the terminal electron acceptor, and various levels of chromate. This mixed culture exhibited chromate tolerance, but not ch romate reduction capability, when growing anaerobically on this medium . However, this culture did exhibit chromate reduction capability when growing anaerobically on TSB. Growth of this culture was not inhibite d by a chromium concentration of 12 mg/L. Mixed cultures exhibited dec reasing diversity with increasing levels of chromate in the enrichment medium. An in situ bioremediation strategy is suggested for chromate contaminated soil and groundwater.