1 research outputs found
Aerobic Vinyl Chloride Metabolism in Groundwater Microcosms by Methanotrophic and Etheneotrophic Bacteria
Vinyl
chloride (VC) is a carcinogen generated in groundwater by
reductive dechlorination of chloroethenes. Under aerobic conditions,
etheneotrophs oxidize ethene and VC, while VC-assimilators can use
VC as their sole source of carbon and energy. Methanotrophs utilize
only methane but can oxidize ethene to epoxyethane and VC to chlorooxirane.
Microcosms were constructed with groundwater from the Carver site
in MA containing these three native microbial types. Methane, ethene,
and VC were added to the microcosms singly or as mixtures. In the
absence of VC, ethene degraded faster when methane was also present.
We hypothesized that methanotroph oxidation of ethene to epoxyethane
competed with their use of methane, and that epoxyethane stimulated
the activity of starved etheneotrophs by inducing the enzyme alkene
monooxygenase. We then developed separate enrichment cultures of Carver
methanotrophs and etheneotrophs, and demonstrated that Carver methanotrophs
can oxidize ethene to epoxyethane, and that starved Carver etheneotrophs
exhibit significantly reduced lag time for ethene utilization when
epoxyethane is added. In our groundwater microcosm tests, when all
three substrates were present, the rate of VC removal was faster than
with either methane or ethene alone, consistent with the idea that
methanotrophs stimulate etheneotroph destruction of VC