Dehalobacter sp. Strain RM1 in Consortium RM Induces Large Fractionation of Stable Carbon Isotopes during Dichloromethane Fermentation

摘要

Background/Objectives. Dichloromethane (DCM), a probable human carcinogen, is a frequently detected contaminant in groundwater at hazardous waste sites. DCM can be subject to biodegradation under both oxic and anoxic conditions. In the presence of oxygen, methylotrophic bacteria degrade DCM using a thiolytic dehalogenation mechanism. Under anoxic conditions, Dehalobacterium formicoaceticum and Dehalobacter strains have been implicated in DCM dehalofermentation to acetate, formate and inorganic chloride. The DCM-fermenting consortium RM contains Dehalobacter sp. strain RM1 and has been demonstrated as an effective bioaugmentation inoculum for DCM remediation in laboratory-based treatability studies. For field applications, tools to establish cause-and-effect relationships between treatment (e.g., bioaugmentation) and declining contaminant concentrations are desirable. Compound specific isotope analysis (CSIA) can potentially distinguish biodegradation from other physical or chemical processes that can also lead to a reduction in contaminant levels. To explore the feasibility of applying CSIA to monitor the anaerobic degradation of DCM by consortium RM, the fractionation of stable carbon isotopes during the dehalofermentation of DCM by Dehalobacter sp. strain RM1 was determined.