Abstract
While the microbial degradation of a chloroxyanion-based herbicide was first observed nearly ninety years ago, only recently have researchers elucidated the underlying mechanisms of perchlorate and chlorate [collectively, (per)chlorate] respiration. Although the obvious application of these metabolisms lies in the bioremediation and attenuation of (per)chlorate in contaminated environments, a diversity of alternative and innovative biotechnological applications has been proposed based on the unique metabolic abilities of dissimilatory (per)chlorate-reducing bacteria (DPRB). This is fueled in part by the unique ability of these organisms to generate molecular oxygen as a transient intermediate of the central pathway of (per)chlorate respiration. This ability, along with other novel aspects of the metabolism, have resulted in a wide and disparate range of potential biotechnological applications being proposed, including enzymatic perchlorate detection; gas gangrene therapy; enhanced xenobiotic bioremediation; oil reservoir bio-souring control; chemostat hygiene control; aeration enhancement in industrial bioreactors; and, biogenic oxygen production for planetary exploration. While previous reviews focus on the fundamental science of microbial (per)chlorate reduction (for example see Youngblut et al., 2016), here, we provide an overview of the emerging biotechnological applications of (per)chlorate respiration and the underlying organisms and enzymes to environmental and biotechnological industries.
Highlights
The oxyanions of chlorine, perchlorate (ClO4−), and chlorate (ClO3−), are highly soluble, strong oxidants that are deposited in the environment through both anthropogenic and natural processes [1,2,3,4,5,6,7,8]
Perchlorate is a common commodity chemical with a diverse range of industrial uses, ranging from pyrotechnics to lubricating oils [4], but it is predominantly used as an energetics booster or oxidant in solid rocket fuels by the munitions industry [4,9,10,11]
Being a powerful oxidant, under most environmental conditions perchlorate is highly stable on account of the high energy of activation that is associated with its reduction [1,9]
Summary
The oxyanions of chlorine, perchlorate (ClO4−), and chlorate (ClO3−), are highly soluble, strong oxidants that are deposited in the environment through both anthropogenic and natural processes [1,2,3,4,5,6,7,8]. Disposal of the excess biomass generated represents a significant operational cost of the treatment process, while any residual labile electron donor in the reactor effluent can stimulate microbial growth in water distribution systems and contribute to the formation of toxic trihalomethanes during disinfection by chlorination [59] These issues led to the proposal of a diversity of alternative advanced reactor designs. An innovative and unorthodox bioreactor concept was developed in 2007 based on the electrochemical stimulation of microbial perchlorate reduction [56,60,61] (Figure 2) In these packed-bed bioelectrical reactors, DPRB use electrons that are provided through a negatively charged cathode set at a redox potential of 500 mV as an electron donor.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
