Metagenomic analysis revealed the presence of novel Actinomycetota “Candidatus Solincola uaceae” sp. nov., obtained from a hot spring

Abstract

Metagenomic analysis of the hot spring led to the recovery of a high-quality metagenome-assembled genome (MAG), MPNR_HS_01, affiliated with the phylum Actinomycetota. Taxonomy analysis assigned the MAG to “Candidatus Solincola”, clustering closely with “Candidatus Solincola tengchongensis”. MPNR_HS_01 was 2.82 Mb in size, assembled into 27 contigs, with a G+C content of 63.4%, 49 tRNAs, 4 rRNAs, 98.7% completeness, and no detectable contamination. Functional annotation revealed the presence of complete glycolysis and nonoxidative pentose phosphate pathways, while the tricarboxylic acid cycle was incomplete. Notably, MPNR_HS_01 encoded Wood–Ljungdahl pathway, suggesting carbon assimilation. Energy conservation was supported by hydrogenases, heterodisulfide reductase, Rnf complex, and V-type ATPase. Stress adaptation traits included genes for heat shock proteins, proline biosynthesis, and ion transporters involved in osmotic homeostasis. Although lacking flagellar machinery, MPNR_HS_01 possessed type IV pili and genes associated with twitching motility. Secondary metabolite analysis identified a betalactone biosynthetic gene cluster. Genome-relatedness analyses showed that MPNR_HS_01 was distinct from “Candidatus Solincola” species, with both average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values falling below the established species threshold (95–96% ANI and 70% for dDDH), supporting its designation as a novel species, for which we propose the name “Candidatus Solincola uaceae” sp. nov.