Microorganisms of Microbial Mats from an Alkaline Hot Spring of Baikal Rift Zone as Bioagents in a Biofuel Cell

Abstract

The microbial diversity, transformation potential and ability of microorganisms of the microbial mat consortium of the Kucheger thermal spring (Baikal Rift Zone) to generate electricity were studied. High-throughput sequencing showed the predominance of representatives of the Proteobacteria phylum in the microbial mat community (85.5% of the number of classified bacterial sequences). Among Proteobacteria, filamentous sulfur bacteria of the genus Thiothrix are the most numerous (66.1%). In addition, bacteria of the families Rhodocyclaceae (3%) and Comamonadaceae (7.3%) were present in the mat community. The Bacteroidetes phylum was represented by sequences belonging mainly to the Flavobacteriaceae family (6.8%). The sequences of other phyla accounted for no more than 0.5% of the total number of classified sequences. A wide metabolic activity of microorganisms of mat Kucheger-15 was revealed. The high electrogenic ability of microorganisms of the consortium of microbial mats Kucheger-15 in biofuel cells (BFCs) is shown. Mat-based BFCs generated electricity by adding substrates such as peptone, cellulose, starch. Peptone, glucose, tween-80, starch, sodium acetate, and cellulose were used as substrates. Peptone turned out to be the most effective substrate for the production of electricity in BFCs based on Kucheger microbial mat microorganisms. The addition of a mixture of these substrates to the anolyte (the concentration of each of them is 2.5 g/l) made it possible to achieve some increase in energy release (especially the output current) compared to BFC based on each of these substrates separately. The presence of a wide variety of different microorganisms with broad substrate specificity, the ability to function under extreme conditions (high temperature, high pH values), their well-coordinated work and adaptation to each other and to the resulting metabolites, and stability over time allow us to speak of high prospects for the use of hot spring mats in BFC technologies.