Aerobic biodegradation of cis-1,2-dichloroethene as sole carbon source: Stable carbon isotope fractionation and growth characteristics

Abstract

Cis-1,2-dichloroethene (cDCE) is a compound of concern at many chloroethene-contaminated sites, since it tends to accumulate during reductive dechlorination of the higher chlorinated ethenes. Stable carbon isotope fractionation during aerobic cDCE biodegradation was observed in groundwater microcosms under varying incubation conditions (room temperature/groundwater temperature; with/without inorganic nutrients), and resulted in an average stable carbon isotope enrichment factor of −15.2 ± 0.5‰. A new enrichment culture, obtained from groundwater microcosms, degraded cDCE concentrations up to 100 mg L −1, was active at temperatures between 4 and 23 °C, had a pH optimum of ∼7, and could withstand prolonged periods (250 d) of starvation. Microbial growth during degradation of cDCE as sole carbon and energy source was demonstrated by protein formation in mineral medium not containing any known auxiliary substrate. The obtained growth yield was 12.5 ± 1.9 g of protein Mol −1 of cDCE, with a doubling time of 53 ± 2 h at 23 °C. Aerobic degradation of cDCE as sole carbon and energy source appears to be a promising biological process for site remediation.