Anaerobic formation of α-hexachlorocyclohexane from γ-hexachlorocyclohexane in soil and by Escherichia coli

Abstract

In two soil types small amounts of α-hexachlorocyclohexane were formed from γ-hexachlorocyclohexane under submerged conditions, but not under aerobic conditions. In the submerged soils γ-tetrachlorocyclohexene was detected as a major metabolite of γ-hexachlorocyclohexane, whereas aerobic soil incubation yielded γ-pentachlorocyclohexene. Growing cultures of Escherichia coli produced α-hexachlorocyclohexane from the γ-isomer only upon anaerobic incubation. Moreover, heavy, washed suspensions of E. coli incubated anaerobically with γ-hexachlorocyclohexane (7.5 mg/liter) in a glucose-phosphate buffer medium converted 1.6% of the γ-hexachlorocyclohexane into the α-isomer in 10 days. Growing mycelia of Aspergillus niger incubated with γ-hexachlorocyclohexane produced no α-isomer.