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 mu mol l(-1)) or vinyl chloride (100 mu mol l(-1)) in the presence of ethene (less than or equal to 80 mu mol l(-1) and less than or equal to 210 mu mol l(-1), respectively). This culture consists of at least five bacterial strains. Ail 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 mu mol l(-1)) was not affected by the presence of trichloroethene (100 mu mol l(-1)) or tetrachloroethene (100 mu 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 less than or equal to 200 mu mol l(-1) cDCE in 300 min.