Acetogenic Microbial Degradation of Vinyl Chloride

Under methanogenic conditions, microbial degradation of [1,2-¹⁴C]vinyl chloride (VC) resulted in significant (14 ± 3% maximum recovery) but transient recovery of radioactivity as ¹⁴C-acetate. Subsequently, ¹⁴C-acetate was degraded to ¹⁴CH₄ and ¹⁴CO₂ (18 ± 2% and 54 ± 3% final recoveries, respectively). In contrast, under 2-bromoethanesulfonic acid (BES) amended conditions, ¹⁴C-acetate recovery remained high (27 ± 1% maximum recovery) throughout the study, no ¹⁴CH₄ was produced, and the final recovery of ¹⁴CO₂ was only 35 ± 4%. These results demonstrate that oxidative acetogenesis may be an important mechanism for anaerobic VC biodegradation. Moreover, these results (1) demonstrate that microbial degradation of VC to CH₄ and CO₂ may involve oxidative acetogenesis followed by acetotrophic methanogenesis and (2) suggest that oxidative acetogenesis may be the initial step in the net oxidation of VC to CO₂ reported previously under Fe(III)-reducing, SO₄-reducing, and humic acids-reducing conditions.