Archaeal (Per)Chlorate Reduction at High Temperature: An Interplay of Biotic and Abiotic Reactions

Abstract

Archaea Powered by Rocket Fuel Perchlorate is a ubiquitous chlorine-based compound that forms naturally in the atmosphere. It is only present in large deposits in a few locations, such as the Atacama Desert in Chile, which has been assumed to be because perchlorate-reducing bacteria normally degrade it into chloride and oxygen. Liebensteiner et al. (p. 85 ; see the Perspective by Nerenberg ), however, found that an archeon, Archaeoglobus fulgidus , can also reduce perchlorate. The archaeal perchlorate reduction pathway shares limited similarity with bacterial perchlorate reduction: Instead of producing chloride and oxygen, enzymatically produced chlorite reacts with sulfide to produce oxidized sulfur compounds. Because hyperthermophilic anaerobic archaea similar to A. fulgidus are thought to have been among the first complex organisms to evolve on Earth, they may have started creating oxidized conditions in some habitats before the emergence of oxygen-generating photosynthesis.