Degradation Pathways of Trichloroethylene and 1,1,1-Trichloroethane by Mycobacterium sp. TA27

Abstract

  We analyzed the kinetics and metabolic pathways of trichloroethylene and 1,1,1-trichloroethane degradation by the ethane-utilizing Mycobacterium sp. TA27. The apparent V_max and K_m of trichloroethylene were 9.8 nmol min⁻¹ mg of cells⁻¹ and 61.9 μM, respectively. The apparent V_max and K_m of 1,1,1-trichloroethane were 0.11 nmol min⁻¹ mg of cells⁻¹ and 3.1 μM, respectively. 2,2,2-trichloroethanol, trichloroacetic acid, chloral, and dichloroacetic acid were detected as metabolites of trichloroethylene. 2,2,2-trichloroethanol, trichloroacetic acid, and dichloroacetic acid were also detected as metabolites of 1,1,1-trichloroethane. The amounts of 2,2,2-trichloroethanol, trichloroacetic acid, chloral, and dichloroacetic acid derived from the degradation of 3.60 μmol trichloroethylene were 0.16 μmol (4.4%), 0.11 μmol (3.1%), 0.02 μmol (0.6%), and 0.02 μmol (0.6%), respectively. The amounts of 2,2,2-trichloroethanol, trichloroacetic acid and dichloroacetic acid derived from the degradation of 1.73 μmol 1,1,1-trichloroethane were 1.48 μmol (85.5%), 0.22 μmol (12.7%), and 0.02 μmol (1.2%), respectively. More than 90% of theoretical total chloride was released in trichloroethylene degradation. Chloral and 2,2,2-trichloroethanol were transformed into each other, and were finally converted to trichloroacetic acid, and dichloroacetic acid. Trichloroacetic acid and dichloroacetic acid were not degraded by strain TA27.