Abstract
The family Beggiatoaceae is currently represented by 25 genera in the Genome Taxonomy Database, of which only 6 have a definite taxonomic status. Two metagenome-assembled genomes (MAGs), WS_Bin1 and WS_Bin3, were assembled from metagenomes of the sulfur mats coating laminaria remnants in the White Sea. Using the obtained MAGs, we first applied phylogenetic analysis based on whole-genome sequences to address the systematics of Beggiatoaceae, which clarify the taxonomy of this family. According to the average nucleotide identity (ANI) and average amino acid identity (AAI) values, MAG WS_Bin3 was assigned to a new genus and a new species in the family Beggiatoaceae, namely, 'Candidatus Albibeggiatoa psychrophila' gen. nov., sp. nov., thus providing the revised taxonomic status of the candidate genus 'BB20'. Analysis of 16S rRNA gene homology allowed us to identify MAG WS_Bin1 as the only currently described species of the genus 'Candidatus Parabeggiatoa', namely, 'Candidatus Parabeggiatoa communis', and consequently assign the candidate genus 'UBA10656', including four new species, to the genus 'Ca. Parabeggiatoa'. Using comparative whole-genome analysis of the members of the genera 'Candidatus Albibeggiatoa' and 'Ca. Parabeggiatoa', we expanded information on the central pathways of carbon, sulfur and nitrogen metabolism in the family Beggiatoaceae.