Ethene as an auxiliary substrate for the cooxidation of cis-1, 2-dichloroethene and vinyl chloride

Cultures able to dechlorinate cis-1,2-dichloroethene (cDCE) were selected with ethene (3-20%, v/v) as the sole source of carbon and energy. One mixed culture (K20) could degrade cDCE (400 &mgr;mol l(-1)) or vinyl chloride (100 &mgr;mol l(-1)) in the presence of ethene (</= 80 &mgr;mol l(-1) and </= 210 &mgr;mol l(-1), respectively). This culture consists of at least five bacterial strains. All five strains were able to degrade cDCE cometabolically in pure culture. The mixed culture K20 was highly tolerant against cDCE (up to 6 mmol l(-1) in the liquid phase). Degradation of cDCE (200 &mgr;mol l(-1)) was not affected by the presence of trichloroethene (100 &mgr;mol l(-1)) or tetrachloroethene (100 &mgr;mol l(-1)). Transformation yields (T(y), defined as unit mass of chloroethene degraded per unit mass of ethene consumed) of the mixed culture K20 were relatively high (0.51 and 0.61 for cDCE and vinyl chloride, respectively). The yield for cDCE with ethene as auxiliary substrate was ninefold higher than any values reported with methane or methane/formate as auxiliary substrate. The viability of the cells of the mixed culture K20 (0.3 mg of cells ml(-1)) was unaffected by the transformation of </= 200 &mgr;mol l(-1) cDCE in 300 min.