Determination of intrinsic monod kinetic parameters for two heterotrophic tetrachloroethene (PCE)‐respiring strains and insight into their application

Abstract

A complete set of mathematically identifiable and meaningful kinetic parameters estimates is needed to accurately describe the activity of individual populations that dehalorespire tetrachloroethene (PCE) and other chlorinated ethenes. These data may be difficult to extract from the literature because kinetic parameter estimates obtained using mixed cultures may reflect the activity of multiple dehalorespiring populations, while those obtained at low initial substrate-to-biomass ratios (S(0)/X(0)) are influenced by culture history and are generally not relevant to other systems. This study focused on estimation of electron donor and acceptor utilization kinetic parameters for the heterotrophic dehalorespirers Desulfuromonas michiganensis strain BB1 and Desulfitobacterium sp. strain PCE1. Electron acceptor utilization kinetic parameters that are identifiable and independent of culture history, i.e., intrinsic, could be estimated at S(0)/X(0) >or= 10, with both concentrations expressed as chemical oxygen demand (COD). However, the parameter estimates did not accurately describe dechlorination kinetics at lower S(0)/X(0) ratios. The maximum specific substrate utilization rates (q(max)) and half-saturation constants (K(S)) for PCE and trichloroethene (TCE) estimated for the two heterotrophic strains are higher than the values reported for Dehalococcoides cultures. These results suggest that the natural niche of Dehalococcoides strains that can metabolize a range of chlorinated ethenes may be to respire dichloroethene and vinyl chloride produced by Desulfuromonas and Desulfitobacterium strains or other populations that dechlorinate PCE and TCE at faster rates. Few data exist on the electron donor utilization kinetics of heterotrophic dehalorespirers. The results of this study suggest that Desulfuromonas and Desulfitobacterium strains should be able to compete for organic electron donors with other heterotrophic populations in the subsurface.

Nitrous Oxide Is a Potent Inhibitor of Bacterial Reductive Dechlorination

“…12,62,63 The current study accomplished kinetic measurements in axenic cultures under defined conditions and over short incubation periods (<6 h, no growth occurred), which facilitates the determination of intrinsic kinetic parameters. 59 The Michaelis−Menten model simulations predicted the behaviors of Geo strain SZ and Dhc strain BAV1 (R 2 > 0.90), and both organisms fit the noncompetitive inhibition model (R 2 > 0.96) with micromolar levels of N 2 O as the inhibitor. These findings imply N 2 O as a noncompetitive inhibitor that oxidizes the Co(I) corrinoid cofactor of RDases, thereby decreasing reductive dechlorination rates.…”

“…Predicting the fate of chlorinated ethenes at bioremediation sites relies on accurate estimates of the intrinsic kinetic parameters of OHRB; 59 however, kinetic constants determinations using various dechlorinating cultures at different cell densities reported highly variable V max and K m values (or K S values when Monod kinetics were applied). 12,60,61 Likely explanations for these discrepancies are that different, potentially competing types of dechlorinators with distinct RDases and present in varied abundances contributed to reductive dechlorination.…”

Adaptation of a Constructed Wetland to Simultaneous Treatment of Monochlorobenzene and Perchloroethene

“…(Maymó-Gatell et al 1999). Several other organisms, such as Dehalobacter, Desulfuromonas, and Desulfitobacterium sp., dechlorinate PCE to trichloroethene (TCE) and dichloroethenes (DCEs), with cis-DCE being the dominant degradation product (Sung et al 2003;Yoshida et al 2007;Huang and Becker 2009). The dechlorination products TCE, DCEs, and vinyl chloride (VC) are increasingly (in the given order) susceptible to microbial transformation under aerobic conditions, which is largely co-metabolic for TCE and cis-DCE (Broholm et al 2005;Fathepure et al 2005;Olaniran et al 2008).…”

Quantifying Impacts of Microcosm Mass Loss on Kinetic Constant Estimation

“…The epistemic error introduced by ignoring experimental mass loss also violates key assumptions of the methods commonly employed in these studies to evaluate the uncertainty of estimated model parameters. For example, classical nonlinear regression analysis techniques, such as the popular spreadsheet-based method employed by five of the MRD modeling studies in Table , ,− hinge upon an assumption of zero-mean error to calculate interval estimates of model parameters . That assumption is violated if large-time model predictions of aqueous concentrations are consistently higher than measured values.…”