Thetidibacter halocola gen. nov., sp. nov., a novel member within the family Roseobacteraceae isolated from seawater

A Gram-staining-negative, strictly aerobic, dark beige-colored, rod-shaped, chemoorganoheterotrophic, and catalase- and oxidase-positive bacterium, designated as KMU-90^T, was isolated from coastal seawater in the Republic of Korea, and subjected to a polyphasic study. The novel isolate was able to grow at 0-6.0% NaCl concentrations (w/v), pH 6.5-9.5, and 4-45 °C. The 16S rRNA gene sequences-based phylogeny revealed that the novel marine isolate belongs to the family Roseobacteraceae of class Alphaproteobacteria and that it shared the greatest sequence similarity (97.3%) with Aestuariicoccus marinus NAP41^T. The novel strain could be distinguished phenotypically from related representatives of the family Roseobacteraceae. The major (> 10%) fatty acids of strain KMU-90^T were C_18:1 ω7c and C_18:1 ω7c 11-methyl and the only respiratory quinone was ubiquinone-10 (Q-10). Strain KMU-90^T contained phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol, two unidentified aminolipids, an unidentified phospholipid, and three unidentified glycolipids as polar lipids. The assembled draft genome size of strain KMU-90^T was 4.84 Mbp with a DNA G + C content of 66.5%. The average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values between the genomes of strain KMU-90^T and its closely related representatives were 77.0-79.0%, 14.6-20.0%, and 60.0-69.9%, respectively. From the polyphasic taxonomic results obtained, the strain is considered to represent a novel genus and a new species of the family Roseobacteraceae, for which the name Thetidibacter halocola gen. nov., sp. nov. is proposed. The type species is T. halocola, with the type strain KMU-90^T (= KCCM 90287^T = NBRC 113375^T).

Limibaculum sediminis sp. nov., isolated from mangrove sediment

A Gram-stain-negative, cream-coloured, aerobic, motile and ovoid- to rod-shaped bacterium, designated as FT325^T, was isolated from mangrove sediment collected in Shenzhen, PR China. The taxonomic position of strain FT325^T was established by phylogenetic, physiological, biochemical and chemotaxonomic analyses. Strain FT325^T grew optimally at 37-40 °C and pH 6.0 in the presence of 0 % (w/v) NaCl. Results of 16S rRNA gene sequence analysis showed that strain FT325^T was most similarly related to Limibaculum halophilum CAU 1123^T (96.2 %), Phaeovulum vinaykumarii DSM 18714^T (93.9%) and Amaricoccus solimangrovi HB 172011^T (93.7 %). The major fatty acids (>10 %) were C_18 : 1  ω7c (60.0 %) and 11-methyl C_18 : 1  ω7c (16.7 %). The sole respiratory quinone was Q-10. The polar lipids were phosphatidylglycerol, one unidentified glycolipid, three unidentified aminolipids and three unidentified phospholipids. Its estimated genome size was 4 318 768 bp and the genomic DNA G+C content was 69.6 mol%. Based on its distinct phenotypic, chemotaxonomic and phylogenetic characteristics, strain FT325^T represents a novel species of the genus Limibaculum, for which the name Limibaculum sediminis sp. nov. is proposed (=MCCC 1K07397^T=KCTC 92313^T).

Pontivivens ytuae sp. nov., isolated from deep sea sediment of the Mariana Trench

A Gram-stain-negative, light pink-coloured, rod-shaped, flagellated and facultative anaerobic bacterial strain, designated MT2928^T, was isolated from deep-sea sediment collected from the Mariana Trench. Growth of strain MT2928^T occurred optimally at 28 °C, pH 8.0-9.0 and in the presence of 1.0-2.0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MT2928^T belongs to the genus Pontivivens and has the highest sequence similarity to Pontivivens insulae GYSW-23^T (96.6 %). Genomic analysis indicated that strain MT2928^T contains a circular chromosome of 4 199 362 bp with G+C content of 67.2 mol%. The strain did not produce bacteriochlorophyll a, but produced carotenoid. The predominant respiratory quinone of MT2928^T was ubiquinone-10. The polar lipids of MT2928^T contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified lipids and two unidentified phospholipids. The major fatty acids of strain MT2928^T contained summed feature 8 (C_18 : 1  ω7c or/and C_18 : 1  ω6c), C_18 : 0 and summed feature 2 (iso-C_16 : 1 I and/or C_14 : 0 3-OH). On the basis of phylogenetic, physiological, biochemical and other phenotypic properties, strain MT2928^T represents a novel species of the genus Pontivivens, and the name Pontivivens ytuae sp. nov. is proposed with the type species MT2928^T (=MCCC 1K05575^T=JCM 34320^T).

Kangsaoukella pontilimi gen. nov., sp. nov., a new member of the family Rhodobacteraceae isolated from a tidal mudflat

A strictly aerobic, Gram-stain-negative, non-motile, ovoid- and rod-shaped bacterium, designated strain GH1-50^T, was isolated from a tidal mudflat sample collected from Dongmak seashore on Gangwha Island, Republic of Korea. The organism showed growth at 20-40 °C (optimum, 30 °C), pH 7-8 (optimum, pH 7) and 2-6  % (w/v) NaCl (optimum, 5 %). The pufLM genes were present but bacteriochlorophyll a was not detected. The major isoprenoid quinone was Q-10. The polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, an unidentified aminolipid and five unidentified lipids. The predominant cellular fatty acids were C_18 : 1  ω7c, C_18 : 1  ω7c 11-methyl and C_18 : 0. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that the isolate belonged to the family Rhodobacteraceae and was loosely associated with members of the recognized genera. The closest relative was the type strain of Pseudoruegeria marinistellae (96.8 % similarity) followed by Boseongicola aestuarii (96.4 %). Other members of the family shared 16S rRNA gene similarity values below 96.0 % to the novel isolate. The DNA G+C content calculated from the draft genome sequence was 64.0 %. The average amino acid identity, average nucleotide identity and digital DNA-DNA hybridization values between genome sequences of strain GH1-50^T and all the type strains of the recognized taxa compared were <70.0, <84.1 and <20.5 %, respectively. Based on data obtained by a polyphasic approach, strain GH1-50^T (=KCTC 72224^T=NBRC 113929^T) represents a novel species of a new genus in the family Rhodobacteraceae, for which the name Kangsaoukella pontilimi gen. nov., sp. nov. is proposed.

Acidimangrovimonas sediminis gen. nov., sp. nov., isolated from mangrove sediment and reclassification of Defluviimonas indica as Acidimangrovimonas indica comb. nov. and Defluviimonas pyrenivorans as Acidimangrovimonas pyrenivorans comb. nov

A Gram-stain-negative, aerobic, non-motile, short-rod bacterium, strain MS2-2^T, was isolated from mangrove sediment sampled at Jiulong River Estuary, Fujian province, PR China. 16S rRNA gene sequence similarity analysis showed that strain MS2-2^T was most closely related to Defluviimonas indica 20V17^T (97.41 %) and Defluviimonas pyrenivorans PrR001^T (96.18 %). Phylogenetic trees based on 16S rRNA genes and genome sequences both revealed that strain MS2-2^T formed a distinct cluster with D. indica 20V17^T and D. pyrenivorans PrR001^T within family Rhodobacteracea, quite separate from other type species in the genus Defluviimonas. The average nucleotide identity value between strain MS2-2^T and D. indica 20V17^T was 78.35 %. Growth of strain MS2-2^T was observed at 16-41 ° C (optimum, 34 ° C), pH 3.6-7.5 (pH 6.0) and 0.5-10.0 % (w/v) NaCl (4.0 %). The major cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C16 : 0 and C18 : 0. Ubiquinone 10 was the sole quinone. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content was 67.9 mol%. The combined genotypic and phenotypic data show that strain MS2-2^T represents a novel species of a novel genus in the family Rhodobacteraceae, for which the name Acidimangrovimonassediminis gen. nov., sp. nov. is proposed, with the type strain MS2-2^T (=MCCC 1K02682^T=NBRC 112978^T). We also propose the reclassification of Defluviimonas indica as Acidimangrovimonas indica comb. nov. and Defluviimonas pyrenivorans as Acidimangrovimonas pyrenivorans comb. nov.