The effects of chromium on the growth and activity of a pentachlorophenol‐degrading bacterium

The effects of chromium (or chromate, as supplied by CrO3) on a pentachlorophenol-degrading Flavobacterium sp. (ATCC 53874) were examined in a liquid bacterial growth medium. Cr6+ concentrations ⩾ 5.0 μg mL−1 caused the complete inhibition of bacterial growth. The EC25, EC50, and EC75 calculated after 96 h of incubation were 0.44, 1.44, and 3.82 μg mL−1, respectively. Cr6+ caused an irreversible reduction in total cell yield during the 21-day incubation. Cr6+ also elicited an increase in the lag time recorded before there was measurable pentachlorophenol (PCP) degradation by this bacterium. There was also an increase in the overall time required for complete degradation of PCP to nondetectable levels. A similar response was noted with all PCP concentrations examined from 10 to 100 μg mL−1. However, a more pronounced response occurred at the lower PCP concentrations. The significance of these data relative to the in situ use of PCP-degrading bacteria for site bioremediation is outlined. © 1994 by John Wiley & Sons, Inc..