RAPID DEHALOGENATION OF 2,4,6-TRICHLOROPHENOL AT ALKALINE PH BY AN ANAEROBIC ENRICHMENT CULTURE

An enrichment culture, derived from the anaerobic stage of a two-step sequential anaerobic-aerobic reactor system which mineralized 2,4,6-tr ichlorophenol, stoichiometrically converted 2,4,6-trichlorophenol to 4 -chlorophenol. Dehalogenation occurred only in alkaline media (pH 8-9) at concentrations of substrate up to 1 mmol l(-1). Formate plus aceta te or trypticase could serve as electron donors. Neither vitamins nor trace elements were required in a chloride-free defined medium. The de halogenating organism was oxygen-resistant, but was not active in medi a which were oxidized with respect to resazurin indicator dye. Most pr obable number counts of the dehalogenating cultures showed that the de halogenating organisms were present in very small numbers, yet catalys ed dehalogenation at rates considerably faster than other dehalogenati ng organisms described in the literature.