Arenibacterium halophilum gen. nov., sp. nov., a halotolerant bacterium in the family Rhodobacteraceae isolated from a coastal sand dune

Mesobacterium pallidum gen. nov., sp. nov., Heliomarina baculiformis gen. nov., sp. nov. and Oricola indica sp. nov., three novel Alphaproteobacteria members isolated from deep-sea water in the southwest Indian ridge

Three Gram-staining-negative, aerobic and rod-shaped strains, designated as T40-1T, T40-3T and JL-62T, were isolated from the deep-sea water in the southwest Indian ridge. For strain T40-1T, growth occurred at 15–37 °C (optimum, 28 °C), pH 6.0–9.0 (optimum, pH 7.5) and in the presence of 0.5–5.0 % NaCl (w/v; optimum, 2.0 %). Strain T40-3T could grow at 15–40 °C (optimum, 28 °C), with 0.5–11.0 % NaCl (optimum, 2.0 %, w/v) at pH 6.0–9.5 (optimum, 8.0). The temperature, pH and salinity ranges for growth of strain JL-62T were 15–40 °C (optimum, 30 °C), pH 5.5–9.0 (optimum, pH 7.5–8.0) and 0.5–9.0 % NaCl (w/v; optimum, 4.0 %). Ubiquinone-10 was the sole ubiquinone in all strains, the major fatty acids (>20 %) were summed feature 8 (C18 : 1  ω7c / C18 : 1  ω6c). The major polar lipids of strains T40-1T and T40-3T were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine and diphosphatidylglycerol. Strain JL-62T contained phosphatidylmonomethylethanolamine, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and sulfoquinovosyldiacylglycerol as major polar lipids. Phylogenetic trees based on 16S rRNA gene and core-genomic sequences revealed affiliation of strains T40-1Tand T40-3T to the family Roseobacteraceae and formed two independent clades from other Roseobacteraceae genera, and those two strains had average nucleotide identities of 62.0–72.0 % to their phylogenetically related species which fell into to the genus boundary range, indicating that they represent two novel genera. While strain JL-62T represents a novel species in the genus Oricola belonging to the family Phyllobacteriaceae , which was supported by overall genomic relatedness index calculations. The DNA G+C contents of strains T40-1T, T40-3T and JL-62T were 66.5, 60.1 and 62.1 mol %, respectively. Based on the polyphasic taxonomic data, strains T40-1T (=MCCC M24557T=KCTC 82975T) and T40-3T (=MCCC 1K05135T=KCTC 82976T) are classified as representing two novel genera belonging to the family Roseobacteraceae with the names Mesobacterium pallidum gen. nov., sp. nov. and Heliomarina baculiformis gen. nov., sp. nov. are proposed, and strain JL-62T (=MCCC M24579T=KCTC 82974T) is proposed to represent a novel species within the genus Oricola with the name Oricola indica sp. nov. is proposed.

Roseibium limicola sp. nov., isolated from tidal mudflat

A novel bacterium, designated strain CAU 1637^T, was isolated from a tidal mudflat. Cells of strain CAU 1637^T were Gram-stain-negative, aerobic, motile with single flagellum and rod-shaped. The optimum conditions for growth were observed at 30 °C, pH 6.0 and in the presence of 2 % (w/v) NaCl. The respiratory quinone was ubiquinone-10. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CAU 1637^T was closely related to the genus Roseibium, with the highest similarity to Roseibium aestuarii NRBC 112946^T (97.4 %), followed by Roseibium hamelinense NRBC 16783^T (96.8 %), Roseibium aquae JCM 19310^T (96.4 %), Roseibium sediminis KCTC 52373^T (95.8 %) and Roseibium denhamense JCM 10543^T (95.3 %). The predominant cellular fatty acids were C_18 : 1  ω7c 11-methyl and summed feature 8 (C_18 : 1  ω7c and/or C_18 : 1  ω6c). The major polar lipids consisted of diphosphatidylglycerol and phosphatidylglycerol. The average nucleotide identity values between the novel isolate and related strains ranged from 71.0 to 76.4 %, and the DNA-DNA hybridization values ranged from 19.3 to 20.3 %. The G+C content was 58.4 mol% and the whole-genome size was 4.6 Mb, which included 17 contigs and 3931 protein-coding genes. Based on the taxonomic data, strain CAU 1637^T represents a novel species of the genus Roseibium, for which the name Roseibium limicola sp. nov. is proposed. The type strain is CAU 1637^T (=KCTC 82429^T=MCCC 1K06080^T).

Oceanomicrobium pacificus gen. nov., sp. nov., a member of the family Rhodobacteraceae isolated from seawater of tropical western Pacific

The Gram-stain-negative, aerobic, ovoid or rod-shaped bacterial strain, designated KN286^T, was isolated from seawater of tropical western Pacific. Growth occurred between 15 and 40 °C (optimally at 30-35 °C), pH 6-9 (optimally at 7.0) and in the presence of 0.5-5.0% (w/v) NaCl (optimally between 2.0 and 3.0%). Strain KN286^T contained Q-10 as the major respiratory quinone. The polar lipid profile contained phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, three phospholipids, three glycolipids, and three unidentified polar lipids. The predominant cellular fatty acid was summed feature 8 (composed of C_18:1ω7c and/or C_18:1ω6c). Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain KN286^T was a member of the family Rhodobacteraceae and formed a distinct lineage. Strain KN286^T has a genome size of 3.25 Mbp and a G + C content of 65.0 mol%. It encoded with some genes for carbohydrate-active enzymes, such as GH20 (Glycoside Hydrolase Family 20) and PL1 (Polysaccharide Lyase Family 1) and did not encode with a set of genes for reduction of nitrate to nitrite (nitrate reductase gamma subunit, respiratory nitrate reductase alpha N-terminal and respiratory nitrate reductase beta C-terminal). Based on phylogenetic analyses with single-copy orthologous clusters, low isDDH value (19.6%), low ANI (72.4%) and low AAI (65.7%) results, differential chemotaxonomic and physiological properties, strain KN286^T represents a novel species of a novel genus of the family Rhodobacteraceae, for which the name Oceanomicrobium pacificus gen. nov., sp. nov. is proposed. The type strain of Oceanomicrobium pacificus is KN286^T (=CGMCC 1.17118^T = KCTC 72430^T).