Effect of increasing pentachlorophenol (PCP) concentrations on bacterial populations in glycine-percolated soils

Abstract

Population changes of several bacterial groups were compared between soils percolated with glycine and amended with different amounts of pentachlorophenol (PCP). PCP retarded the increase in total viable bacteria with increasing doses of PCP. The increase was followed by a gradual decrease, but the numbers in the soil remained at the maximum level for a short time in the presence of large amounts of PCP. The numbers of Gram-negative bacteria and PCP-tolerant bacterial cells increased dramatically, being followed by a comparable decrease, although the former was always slightly larger than the latter. PCP reduced spore counts. PCP and glycine in the percolation fluid dissipated during the percolation, but the dissipation of glycine was slowed by the presence of increased amounts of PCP. Large portions of PCP were detected in the liquid at the late stage of percolation. Changes in pH suggested biochemical reactions in the percolated soil. The changes differed according to the amount of PCP.