From natural samples 11 isolates able to remove trichloroethene (CCl2CHCl) from an aqueous environment were obtained which were capable of cometabolic degradation of CCl2CHCl by an enzyme system for phenol degradation. At an initial CCl2CHCl concentration of 1 mg/L, the resting cells of particular cultures degraded 33-94% CCl2CHCl during 1 d and their transformation capacity ranged from 0.3 to 3.1 mg CCl2CHCl per g organic fraction. An analysis of a mixed phenol-fed culture with an excellent trichloroethene-degrading ability found a markedly minority isolate represented in the consortium to be responsible for this property. This culture degraded CCl2CHCl even at a low inoculum concentration and attained a transformation capacity of 14.7 mg CCl2CHCl per g. The increase in chloride concentration after degradation was quantitative when compared with the decrease in organically bound chlorine. The degree of CCl2CHCl degradation was affected by Me2S2; this substance can significantly reduce the degrading ability of some tested cultures (> 60%); however, it does not cause this inhibition with others.