Paradonghicola geojensis gen. nov., sp. nov., isolated from seawater, Geoje-si, South Korea

Marivivens marinum sp. nov., isolated from tidal flat, Gochang, South Korea

A Gram-negative, rod-shaped, non-motile, aerobic bacterium, designated MK-3T, was isolated from shallow seawater in Gochang, Republic of Korea. Growth of strain MK-3T occurred at 15-40 °C (30 °C), pH 6.0-7.0 (pH 7.0) and in the presence of 2-3 % NaCl (2%). Phylogenetic analysis based on the 16S rRNA gene sequence placed strain MK-3T within the family Roseobacteraceae. It exhibited sequence similarities of 95.7% with Salipiger marinus CK-I3-6T, Salipiger aestuarii DSM 22011T and Salipiger pentaromativorans P9T; 95.4% with Ruegeria alba 1NDH52CT, Salipiger manganoxidans VSW210T and Salipiger thiooxidans DSM 10146T; 95.3% with Marivivens donghaensis AM-4T and Histidinibacterium lentulum B17T; and 95.2% with Marivivens geojensis FJ12T. Phylogenetic and phylogenomic analyses consistently demonstrated that strain MK-3T formed a distinct lineage within the genus Marivivens, clustering with its closest relatives. The major fatty acids were C18 : 1  ω7c/C18 : 1  ω6c, C18 : 1  ω7c 11-methyl and C16 : 0. The genome length of strain MK-3T was 3.3 Mbp, and the DNA G+C content was 62.8 mol%. The strain contained Q-10 as the major ubiquinone. The polar lipids consisted of three phosphatidylinositol mannosides and a diphosphatidylglycerol. Based on its phenotypic, chemotaxonomic, phylogenetic and genomic characteristics, strain MK-3T represents a novel species in the genus Marivivens, for which the name Marivivens marinum sp. nov. is proposed. The type strain is MK-3T (=KEMB 21417T=KCTC 8294T=JCM 36630T).

Aestuarium zhoushanense is a later heterotypic synonym of Marivivens donghaensis, and transfer of Paradonghicola geojensis to the genus Marivivens as Marivivens geojensis comb. nov

The 16S rRNA genes of Aestuarium zhoushanense G7T and Paradonghicola geojensis FJ12T shared 100 % sequence identity with Marivivens donghaensis AM-4T. Phylogeny of 16S rRNA gene sequences showed that the three type strains formed a monophyletic clade within the genus Marivivens . Whole genome sequence comparisons showed that three type strains shared 46.7–69.7 % digital DNA–DNA hybridization, 92.1–96.4 % average nucleotide identity and 96.2–98.1 % average amino acid identity. The high 16S rRNA gene similarity values show that three type strains should belong to the same genus. The pan-genome of the five strains contained 5754 genes including 1877 core genes. Based on the principle of priority, we propose that A. zhoushanense Yu et al. 2019 is a later heterotypic synonym of M. donghaensis Park et al. 2016, and P. geojensis should be reclassified as Marivivens geojensis comb. nov., respectively.