A Novel Species of the Genus Thermanaerothrix Isolated from a Kamchatka Hot Spring Possesses Hydrolytic Capabilities.

Hot springs are inhabited by specific microbial communities which are reservoirs of novel taxa. In this work strain 4228-RoL was isolated from the Solnechny hot spring, Uzon Caldera, Kamchatka. Cells of the strain 4228-RoL were Gram-negative rods forming multicellular filaments. The strain grew optimally at 60 °C and pH 7.0 and fermented various organic compounds including polysaccharides (microcrystalline cellulose, xylan, chitin, starch, dextrin, dextran, beta-glucan, galactomannan, glucomannan, mannan). Major fatty acids were iso-C, C, C, C, iso-C, anteiso-C and C. Genome of the strain was of 3.25 Mbp with GC content of 54.2%. Based on the whole genome comparisons and phylogenomic analysis the new isolate was affiliated to a novel species of Thermanaerothrix genus within Anaerolineae class of phylum Chloroflexota, for which the name T. solaris sp. nov. was proposed with 4228-RoL (= VKM B-3776 = UQM 41594 = BIM B-2058) as the type strain. 114 CAZymes including 43 glycoside hydrolases were found to be encoded in the genome of strain 4228-RoL. Cell-bound and extracellular enzymes of strain 4228-RoL were active against starch, dextran, mannan, xylan and various kinds of celluloses, with the highest activity against beta-glucan. Altogether, growth experiments, enzymatic activities determination and genomic analysis suggested that T. solaris strain 4228-RoL could serve as a source of glycosidases suitable for plant biomass hydrolysis.