Degradation of chlorinated phenols by a toluene enriched microbial culture

Biotransformations of several chlorinated phenols were studied in aerobic cultures enriched on glucose, methane, phenol and toluene and acclimated to 16 chlorinated compounds. The toluene enrichment culture degraded pentachlorophenol (PCP) and 2,4,6-trichlorophenol (2,4,6-TCP), while the cultures enriched on glucose, methane or phenol showed little or no activity. The phenol and toluene enriched cultures rapidly degraded 2,4-dichlorophenol (2,4-DCP) but not 2,6-DCP or 2,4,5-TCP. Degradation of chlorophenols by the toluene enriched culture did not occur endogenously but continued when wnother carbon source, acetate, was introduced. Degradation of chlorophenols proceeded after starvation and in the presence of chloramphenicol, suggesting constitutive enzymatic activity. The initial steps of PCP degradation by the toluene enriched culture involved dechlorination and hydroxylation of an ortho carbon to form tetrachlorocatechol. Tetrachloroguaiacol was identified as a minor, dead-end metabolite of PCP degradation by the toluene enriched culture.