Mechanism of aerobic transformation of carbon tetrachloride by poplar cells

The biochemical mechanism of carbon tetrachloride transformation by poplar cells was investigated using an axenic poplar cell culture. After one-day incubations of poplar cells under aerobic conditions, about 1.5% of dosed carbon tetrachloride was transformed to carbon dioxide, about 0.001% to chloroform and about 3% of the carbon was bound to insoluble poplar cellular materials. The production of carbon dioxide increased under aerobic conditions while the formation of chloroform and cell binding of carbon tetrachloride-carbon was enhanced under anaerobic conditions. Both carbon dioxide production and cell binding were significantly inhibited by a general inhibitor of cytochrome P-450 activity (carbon monoxide) and by specific P-450 2E1 inhibitors (chlorzoxazone, isoniazid, 4-methylpyrazole and 1-phenylimidazole). However, no inhibitory effects were observed when the cells were incubated in the presence of lignin peroxidase inhibitors (NaVO3 and 3-amino-1,2,4-triazole). These results suggest that an enzyme similar to mammalian cytochrome P450-2E1 is involved in the metabolism of carbon tetrachloride by poplar cells. This study demonstrates an environmental biodegradative process for carbon tetrachloride that operates under aerobic conditions.