Transformation of tetra- and trichloromethane to CO₂by anaerobic bacteria is a non-enzymic process

Abstract

Degradation of tetrachloromethane was examined in the three strictly anaerobic bacteria, Acetobacterium woodii, Desulfobacterium autotrophicum and Methanobacterium thermoautotrophicum When incubated under anaerobic conditions in reduced buffer, suspensions of each organism degraded CCl4 by both reductive and substitutive mechanisms. The products formed included less-highly chlorinated methanes and CO2. Cell-free extracts of A. woodii degraded tetrachloromethane in a manner similar to that in whole cells but at a lower rate (63 vs. 110 μkat/kg of protein). When M. thermoautotrophicum or A. woodii was autoclaved, reductive dechlorination was partly abolished, whereas substitutive dechlorination was retained. Trichloromethane was oxidized to CO2 by both native and autoclaved cells of A. woodii. Halomethanes are thus degraded anaerobically by reductive, substitutive and oxidative mechanisms.