Electron acceptor interactions between organohalide-respiring bacteria: Cross-feeding, competition, and inhibition

Abstract

Because of the stepwise, progressive nature of reductive dehalogenation reactions, polyhalogenated parent electron acceptors and their corresponding intermediary dehalogenation products are almost always simultaneously present in the environments where these processes occur. Moreover, a wide variety of polyhalogenated industrial chemicals find their way into the environment, frequently at the same manufacturing or processing facility, resulting in complex mixtures of pollutants in the subsurface. Therefore, cross-feeding, competition, and inhibition are inevitable in these systems and their magnitude or impact must be quantified to better predict and promote the rate and extent of detoxification. Numerical simulations of reactive transport that incorporate fitted parameters describing these processes provide useful tools to evaluate scenarios. Direct experimental evidence of inhibition or competition using defined enzyme and microbial assays provides a more mechanistic understanding of these effects. Combining carefully executed, well-designed experiments with modeling ultimately provides the most useful data for fundamental understanding as well as decision-making in the context of remediation.