Microbial respiration with chlorine oxyanions: diversity and physiological and biochemical properties of chlorate‐ and perchlorate‐reducing microorganisms

Abstract

Chlorine oxyanions are valuable electron acceptors for microorganisms. Recent findings have shed light on the natural formation of chlorine oxyanions in the environment. These suggest a permanent introduction of respective compounds on Earth, long before their anthropogenic manufacture. Microorganisms that are able to grow by the reduction of chlorate and perchlorate are affiliated with phylogenetically diverse lineages, spanning from the Proteobacteria to the Firmicutes and archaeal microorganisms. Microbial reduction of chlorine oxyanions can be found in diverse environments and different environmental conditions (temperature, salinities, pH). It commonly involves the enzymes perchlorate reductase (Pcr) or chlorate reductase (Clr) and chlorite dismutase (Cld). Horizontal gene transfer seems to play an important role for the acquisition of functional genes. Novel and efficient Clds were isolated from microorganisms incapable of growing on chlorine oxyanions. Archaea seem to use a periplasmic Nar-type reductase (pNar) for perchlorate reduction and lack a functional Cld. Chlorite is possibly eliminated by alternative (abiotic) reactions. This was already demonstrated for Archaeoglobus fulgidus, which uses reduced sulfur compounds to detoxify chlorite. A broad biochemical diversity of the trait, its environmental dispersal, and the occurrence of relevant enzymes in diverse lineages may indicate early adaptations of life toward chlorine oxyanions on Earth.

Anaerobic Metabolism in Haloferax Genus

“…Horizontal gene transfer seems to play an important role for the acquisition of functional genes. Novel and efficient Clds were isolated from microorganisms incapable of growing on chlorine oxyanions (Liebensteiner, Oosterkamp & Stams, 2015).…”

Spatial Pattern of Bacterial Community Diversity Formed in Different Groundwater Field Corresponding to Electron Donors and Acceptors Distributions at a Petroleum-Contaminated Site

“…The species of Pseudomonas in the study site was Pseudomonas mendocina, which can degrade toluene [35]. The Dechloromonas in the aquifer shared a 99% sequence similarity with Dechloromonas hortensis and Dechloromonas denitrificans, which can use ClO4 − , ClO3 − , NO3 − , and O2 as electron acceptors to oxidize organic compounds, such as aromatic hydrocarbons [36,37]. Pseudoxanthomonas can produce biosurfactants and can be used to degrade BTEX [38,39].…”

Identification of a parasitic symbiosis between respiratory metabolisms in the biogeochemical chlorine cycle

“…The chlorine cycle consists of the biological, geological, and chemical processes that interconvert organic and inorganic chlorine compounds (Atashgahi et al 2018). Chlorine oxyanions are a group of inorganic chlorine compounds of particular interest in biology due to their high reduction potentials (E 0’ > 0.7 V) (Liebensteiner et al 2016, McCullough and Hazen 2003, Winterbourn 2008, Youngblut et al 2016b). Hypochlorite (ClO - ) and chlorite (ClO 2 - ) are highly reactive compounds that damage cells through oxidative chemistry (Gray et al 2013, Hofbauer et al 2016, Melnyk et al 2015), while chlorate (ClO 3 - ) and perchlorate (ClO 4 - ) are used as electron acceptors in respiration by some bacteria and archaea (Youngblut et al 2016b).…”