Cometabolic and growth-linked biodegradation of vinyl chloride under aerobic conditions

This thesis reports on isolation of three aerobic microorganisms that are capable of growth-linked or cometabolic biodegradation of vinyl chloride (VC).; Pseudomonas aeruginosa strain MF1 was isolated on VC as a sole carbon and energy source, with an observed yield of 0.20 mg total suspended solids (TSS)/mg VC and a maximum specific growth rate (μ _max) of 0.0048 d−1. MF1 dechlorinated VC and mineralized or incorporated it into cell mass. This represents the first report of a Pseudomonas capable of growth on VC. In contrast to previous isolates, MF1 was able to resume VC use after extended periods (>24 days) without any substrate. However, MF1 did not recover the ability to degrade VC when deprived of oxygen for 2.5 days. The likely metabolic pathway for VC metabolism is a monooxygenase initiated transformation into VC-epoxide that enters the TCA cycle via acetyl-CoA.; Pseudomonas sp. strain EA1 was isolated on ethane as a sole carbon and energy source and cometabolizes VC. It is the first Pseudomonas reported with the ability to grow on ethane. The transformation capacity of resting cells is 1.03 μmol VC/mg TSS. Almost half of the VC consumed by EA1 is released as a soluble, non-chlorinated product. The presence, but not consumption, of ethane led to a faster initial VC degradation rate and a decrease in the VC transformation capacity. A conceptual and mathematical model of VC cometabolism kinetics was developed in order to describe this novel type of primary substrate and cometabolite interaction.; P. aeruginosa strain DL1 was isolated on ethene as a primary substrate and rapidly cometabolizes VC. With extended incubation, DL1 transitions to use of VC as a primary substrate, with an observed yield of 0.21 mg TSS/mg VC and μ_max of 0.046 d−1. Cometabolism of VC was stimulated by low ethene concentrations, but consumption of larger amounts of ethene decreased the total amount of VC degraded. A conceptual and mathematical model was developed that describes the cometabolism kinetics.; These findings demonstrate the existence of isolates that can aerobically grow on VC in a robust manner, or cometabolize VC rapidly when grown on ethene or ethane.