The metagenome of foulings from sulfidic spring “Serovodorodny” (Tatarstan, Russia), where members of the genus Thiothrix was observed, was sequenced. Representatives of the phyla Gammaproteobacteria, Cyanobacteria and Campilobacteriota dominated in the microbial community. The complete genome of Thiothrix sp. KT was assembled from the metagenome. It displayed 93.93–99.72% 16S rRNA gene sequence identity to other Thiothrix species. The average nucleotide identity (ANI) и digital DNA-DNA hybridization (dDDH) showed that the genome designated KT represents a new species within the genus Thiothrix, ‘Candidatus Thiothrix sulfatifontis’ sp. nov. KT. The taxonomic status has been determined of the strain Thiothrix sp. CT3, isolated about 30 years ago and not assigned to any of Thiothrix species due to high 16S rRNA gene sequence identity with related species (i.e., 98.8–99.4%). The complete genome sequence of strain CT3 was determined. The ANI between CT3 and other Thiothrix species was below 82%, and the dDDH values were less than 40%, indicating that strain CT3 belongs to a novel species, Thiothrix winogradskyi sp. nov. A genome analysis showed that both strains are chemo-organoheterotrophs, chemolithotrophs (in the presence of hydrogen sulfide and thiosulfate) and chemoautotrophs. For the first time, representatives of Thiothrix showed anaerobic growth in the presence of thiosulfate.
The recently described superphylum DPANN includes several phyla of uncultivated archaea with small cell sizes, reduced genomes, and limited metabolic capabilities. One of these phyla, “
. Micrarchaeota,” comprises an enigmatic group of archaea found in acid mine drainage environments, the archaeal Richmond Mine acidophilic nanoorganisms (ARMAN) group. Analysis of their reduced genomes revealed the absence of key metabolic pathways consistent with their partner-associated lifestyle, and physical associations of ARMAN cells with their hosts were documented. However, “
. Micrarchaeota” include several lineages besides the ARMAN group found in nonacidic environments, and none of them have been characterized. Here, we report a complete genome of “
. Micrarchaeota” from a non-ARMAN lineage. Analysis of this genome revealed the presence of metabolic capacities lost in ARMAN genomes that could enable a free-living lifestyle. These results expand our understanding of genetic diversity, lifestyle, and evolution of “
A highly salt-tolerant and alkaliphilic syntrophic consortium that degrades butyrate under sulfate-reducing conditions was purified from a hypersaline soda lake in southwest Siberia. Here, we present the complete genome sequence of the syntrophic primary butyrate degrader in order to understand the molecular mechanisms of interaction between consortium members.
Strain 768-28 was isolated from a hot spring in Kamchatka, Russia, and represents a novel member of the
genus. The complete genome sequence of this thermoacidophilic anaerobic crenarchaeon reveals genes for protein and carbohydrate-active enzymes, the Embden-Meyerhof and Entner-Doudoroff pathways for glucose metabolism, the tricarboxylic acid cycle, beta-oxidation of fatty acids, and sulfate reduction.