Acidophilic chemolithotrophic microorganisms: prospects for use in biohydrometallurgy and microbial fuel cells

Abstract

Acidophilic chemolithotrophic microorganisms are used in biohydrometallurgy for the extraction of metals from sulphide ores. Some types of microorganisms belonging to this group are capable of generating electricity under certain conditions. This circumstance determined a recent upsurge of research interest in their use in biofuel cells. Under a constant supply of the substrate to the bioelectrochemical system, acidophilic chemolithotrophic microorganisms are capable of producing electricity for a prolonged period of time. The use of extremophiles in microbial fuel cells is of particular interest, since these microorganisms can serve as bioelectrocatalysts at extreme pH, salinity and temperature, while the vast majority of microorganisms are unable to survive under these conditions. Therefore, selection of optimal conditions and approaches to controlling the work of acidophilic chemolithotrophic microorganisms in such fuel cells is of particular importance. On this basis, a technology for the simulteneous bioleaching of metals from poor ores and the generation of electricity can be developed. Biofuel cells operating at low pH values using acidophilic chemolithotrophic microorganisms are yet to be investigated. The number of studies on acidophilic electroactive microorganisms is very limited. In this regard, the purpose of this review was to consider the prospects for the use of acidophilic chemolithotrophic microorganisms as bioagents in microbial fuel cells. The reviewed publications demonstrate that chemolithotrophic microorganisms can act as both anodic (metal-reducing, sulphur-oxidizing microorganisms) and cathodic (metal-oxidizing prokaryotes, sulfate reducers) highly efficient bioagents capable of using mining wastes as substrates.