Use of vinyl chloride as a growth substrate by aerobic bacteria: Pathway analysis and involvement of linear plasmids

Vinyl chloride (VC) is a significant environmental contaminant. A better understanding of aerobic VC metabolism is needed to help predict when this process will or will not occur in the environment.{09}The overall objectives of this research were to isolate novel organisms capable of aerobic growth on VC, elucidate the pathways of these isolates, and compare the pathways to other alkene metabolizing organisms.; Pseudomonas putida strain AJ and Ochrobactrum sp. strain TD were isolated from hazardous waste sites in California and South Carolina, respectively, based on their ability to use VC as a sole source of carbon and energy under aerobic conditions. Strain TD is the first Ochrobactrum reported with this metabolic capability.; Pseudmonas putida strain AJ and Ochrobactrum sp. strain TD utilize epoxyalkane CoM transferase (EaCoMT) during metabolism of VC, ethene, and ethylene oxide. Reduced glutathione was not involved in the catabolism of ethylene oxide for these microbes. These results extend the range of eubacteria known to use coenzyme M in the biodegradation pathways of alkenes.; The involvement of a carboxylase in metabolism of VC, ethene and ethylene oxide by strains AJ and TD was examined. With resting cells of strain TD, the maximum specific rate of ethylene oxide consumption decreased significantly in the absence of external CO2 (trapped in KOH), in comparison to cells provided with room air or added CO2. The amount of 14CO2 incorporated into biomass by resting cells of strain TD grown on ethylene oxide increased by more than a factor of 30 when the substrate was ethylene oxide versus acetate. Acetate was used as a control, to determine the amount of incorporation with a substrate that does not use CO2 during catabolism. These results strongly suggest that strain TD uses CO2 as a reactant during ethylene oxide catabolism. With resting cells of strain AJ, the maximum specific rate of ethylene oxide consumption was not affected by the absence of external CO2 (trapped in KOH), in comparison to cells provided with room air or added CO2. The amount of 14CO2 incorporated into biomass by resting cells of strain AJ grown on ethylene oxide was not significantly greater than when acetate was used as a substrate. These results suggest that, unlike strain TD, strain AJ does not incorporate CO2 during catabolism of ethylene oxide, and by extension, VC and ethene. Further studies are needed to determine how strain AJ processes the product formed by reaction of ethylene oxide and VC-epoxide with coenzyme M. (Abstract shortened by UMI.)...