A sulfate-reducing bacterial genus, Desulfosediminicola gen. nov., comprising two novel species cultivated from tidal-flat sediments

Tidal-flat sediments harbor a diverse array of sulfate-reducing bacteria. To isolate novel sulfate-reducing bacteria and determine their abundance, a tidal-flat sediment sample collected off Ganghwa Island (Korea) was investigated using cultivation-based and culture-independent approaches. Two Gram-stain-negative, strictly anaerobic, rod-shaped, sulfate-reducing bacteria, designated IMCC35004^T and IMCC35005^T, were isolated from the sample. The two strains reduced sulfate, sulfite, elemental sulfur, thiosulfate, Fe(III) citrate, and Mn(IV) oxide by utilizing several carbon sources, including acetate. The 16S rRNA gene amplicon sequencing revealed that the tidal-flat sediment contained diverse members of the phylum Desulfobacterota, and the phylotypes related to IMCC35004^T and IMCC35005^T were < 1%. The two strains shared 97.6% similarity in 16S rRNA gene sequence and were closely related to Desulfopila aestuarii DSM 18488^T (96.1–96.5%). The average nucleotide identity, level of digital DNA–DNA hybridization, average amino acid identity, and percentages of conserved proteins determined analyzing the whole-genome sequences, as well as the chemotaxonomic data showed that the two strains belong to two novel species of a novel genus. Additionally, genes related to dissimilatory sulfate reduction were detected in the genomes of the two strains. Unlike the genera Desulfopila and Desulfotalea, IMCC35004^T and IMCC35005^T contained menaquinone-5 as the major respiratory quinone. Collectively, IMCC35004^T and IMCC35005^T were concluded to represent two novel species of a novel genus within the family Desulfocapsaceae, for which the names Desulfosediminicola ganghwensis gen. nov., sp. nov. (IMCC35004^T = KCTC 15826^T = NBRC 114003^T) and Desulfosediminicola flagellatus sp. nov. (IMCC35005^T = KCTC 15827^T = NBRC 114004^T) are proposed.