Mesobacterium hydrothermale sp. nov., isolated from shallow-sea hydrothermal systems off Kueishantao Island.

A Gram-negative, rod-shaped, non-motile, aerobic bacterium, designated as strain TK19101T, was isolated from the intermediate seawater of yellow vent in the shallow-sea hydrothermal system located near Kueishantao Island. The strain was found to grow at 10-40 °C (optimum, 35 °C), at pH 6.0-8.0 (optimum, 7.0), and in 0-5% (w/v) NaCl (optimum, 1%). Strain TK19101T was catalase-positive and oxidase-positive. The predominant fatty acids (> 10%) in strain TK19101T cells were C16:0, summed feature 8 (C18:1 ω6c and/or C18:1 ω7c), and C18:0. The predominant isoprenoid quinone of strain TK19101T was ubiquinone-10. The polar lipids of strain TK19101T comprised phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phospholipid, and unknown polar lipid. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain TK19101T belonged to the genus Mesobacterium. Strain TK19101T exhibited highest 16S rRNA gene sequence similarity value to Mesobacterium pallidum MCCC M24557T (97.48%). The estimated average nucleotide identity and digital DNA-DNA hybridization values between strain TK19101T and the closest related species Mesobacterium pallidum MCCC M24557T were 74.88% and 20.30%, respectively. The DNA G + C content was 63.49 mol%. On the basis of the analysis of 16S rRNA gene sequences, genotypic and phylogenetic data, strain TK19101T has a unique phylogenetic status and represents a novel species of genus Mesobacterium, for which the name Mesobacterium hydrothermale sp. nov. is proposed. The type strain is TK19101T (= MCCC 1K08936T = KCTC 8354T).

Roseihalotalea indica gen. nov., sp. nov., a halophilic Bacteroidetes from mesopelagic Southwest Indian Ocean with higher carbohydrate metabolic potential.

The pink-colored and strictly aerobic bacterium strain, designated as TK19036T, was isolated from mesopelagic layer of the Southwest Indian Ocean. This novel isolate can grow at 10-45 °C (optimum, 30 °C), pH 6.0-8.0 (optimum, pH 7.0), and 2-14% NaCl concentrations (w/v) (optimum, 6%). The predominant respiratory quinone was Menaquinone-7. Major polar lipid profiles contained two aminolipids, aminophospholipid, two glycolipids, phosphatidylethanolamine, and three unknown polar lipids. The preponderant cellular fatty acids were iso-C15:0, C16:1 ω5c and iso-C17:0 3-OH. Phylogenetic analyses based on 16S rRNA gene sequence uncovered that the strain TK19036T pertained to the family Catalinimonadaceae under phylum Bacteroidota, and formed a distinct lineage with the closed species Tunicatimonas pelagia NBRC 107804T. The up-to-bacteria-core gene phylogenetic trees also demonstrated a deep and novel branch formed by the strain TK19036T within the family Catalinimonadaceae. Based on chemotaxonomic, phylogenetic and genomic features presented above, strain TK19036T represents a novel species from a novel genus of the family Catalinimonadaceae, for which the name Roseihalotalea indica gen. nov. sp. nov. is proposed. The type strain is TK19036T (= CGMCC 1.18940T = NBRC 116371T).

Thermobacterium salinum gen. nov., sp. nov., a novel member of the family Flavobacteriaceae isolated from a hydrothermal zone.

A Gram-stain-negative, aerobic, non-motile and rod-shaped bacterial strain, designated as strain TK19130T, was isolated from the Lonqi hydrothermal zone in the Southwest Indian Ridge. Growth occurred with 1-12 % (w/v) NaCl (optimum, 2-4 %), at 10-40 °C (optimum, 30-35 °C) and at pH 6.0-9.0 (optimum, pH 7.0-8.0). The genome of strain TK19130T was 3.15 Mb, with a DNA G+C content of 41.35 %. Based on the results of 16S rRNA gene sequence analysis, strain TK19130T was affiliated with the family Flavobacteriaceae, in which the highest similarity was 90.54 % to Aureisphaera salina A6D-50T, under the genus demarcation boundary (94.50 %). Average nucleotide identity values between strain TK19130T and adjacent strains were 67.17-72.00 %, lower than the recommended threshold of 73.98 % for genus delineation. The predominant respiratory quinone of strain TK19130T was menaquinone 6. Major polar lipids were phosphatidylethanolamine, three aminolipids and one unidentified polar lipid. Major fatty acids were detected as iso-C15 : 1 G, iso-C15 : 0 and iso-C17 : 0 3-OH. Based on the polyphasic taxonomic evidence presented above, strain TK19130T formed an independent branch representing a new species of a novel genus within the family Flavobacteriaceae, for which the name Thermobacterium salinum gen. nov., sp. nov. is proposed. The type strain is TK19130T (=CGMCC 1.18993T=JCM 35842T=MCCC M28200T).

Paracoccus albicereus sp. nov., isolated from the shallow-sea hydrothermal system off Kueishantao Island.

Strain designated TK19116T was isolated from the shallow-sea hydrothermal systems off Kueishantao Island in Taiwan, China. The bacterium was Gram-stain-negative, aerobic, oxidase-positive and catalase-positive. Cells of the strain TK19116T were short-rod-shaped and non-motile. The results of phylogenetic analysis of 16S rRNA gene sequences indicated that strain TK19116T belonged to the genus Paracoccus, with the highest sequence similarity to Paracoccus alkanivorans 4-2T (97.1 %). The average nucleotide identity values between the strain TK19116T with Paracoccus alkanivorans 4-2T, Paracoccus zhejiangensis J6T, Paracoccus siganidrum M26T and Paracoccus tegillarcae BM15T were 75.3, 76.7, 76.7 and 75.8%, respectively. The digital DNA-DNA hybridization value between the strain TK19116T with Paracoccus alkanivorans 4-2T, Paracoccus zhejiangensis J6T, Paracoccus siganidrum M26T and Paracoccus tegillarcae BM15T were 19.7, 20.3, 20.5 and 20.0%, respectively. The main respiratory quinone of strain TK19116T was ubiquinone 10. The polar lipids include aminolipid, phosphatidylcholine, diphosphatidylglycerol, glycolipid, phosphatidylglycerol and phospholipid. The principal fatty acid of strain TK19116T was summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c). The G+C content of the chromosomal DNA was 64.2 %. The combination of the results of the phylogenetic, phenotypic and chemotaxonomic analysis, strain TK19116T represents a novel species of the genus Paracoccus, for which the name Paracoccus albicereus sp. nov. is proposed. The type strain is TK19116T (= MCCC 1K08025T=JCM 35527T).

Roseovarius carneus sp. nov., a novel bacterium isolated from a coastal phytoplankton bloom in Xiamen.

A Gram-stain-negative, non-motile, ovoid or short rod shaped and aerobic marine bacterium, designated as strain LXJ103T, was isolated from a coastal phytoplankton bloom in Xiamen, PR China. Cells were oxidase- and catalase-positive. Strain LXJ103T grew at 4-40 °C (optimum, 28-37 °C), at pH 6-10 (optimum, pH 8.5) and with 1-15 % (w/v) NaCl (optimum, 3 %). The major cellular fatty acids (>10 %) were iso-C18 : 1 ω7c/iso-C18 : 1 ω6c (70.2 %) and C16 : 0 (10.3 %). The following polar lipids were found to be present: phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and five unknown glycolipids. The predominant respiratory quinone was ubiquinone-10. Strain LXJ103T exhibited the highest 16S rRNA gene sequence similarity to Roseovarius litorisediminis D1-W8T (96.97 %). The phylogenetic trees based on 16S rRNA gene sequences showed that strain LXJ103T was a member of the genus Roseovarius. The draft genome size of strain LXJ103T is 3.05 Mb with a genomic G+C content of 61.22 mol%. The digital DNA-DNA genome hybridization value of strain LXJ103T compared with the most similar type strain R. litorisediminis CECT 8287T was 18.80 %. The average nucleotide identity value between strain LXJ103T and R. litorisediminis CECT 8287T was 72.60 %. On the basis of polyphasic data, strain LXJ103T represents a novel species of the genus Roseovarius, for which the name Roseovarius carneus sp. nov. is proposed. The type strain is LXJ103T (=CGMCC 1.19168T=MCCC 1K06527T=JCM 34778T).

Yeosuana marina sp. nov., isolated from shallow-sea hydrothermal systems off Kueishantao Island.

A novel Gram-stain-negative, non-flagellated, non-motile, rod-shaped (0.4-0.6×1.8-2.5 µm), aerobic bacterial strain, designated JLT21T, was isolated from seawater of a shallow-sea hydrothermal system. Growth occurred with 0-4.0 % (w/v) NaCl (optimum, 2.0 % NaCl), at 8-45 °C (optimum, 25 °C) and at pH 3.0-10.0 (optimum, pH 7.0). Analysis of 16S rRNA gene sequences revealed that strain JLT21T showed the highest 16S rRNA gene sequence similarity to Gaetbulibacter aquiaggeris KEM-8T (97.2 %), Gaetbulibacter marinus IMCC1914T (96.9 %) and Yeosuana aromativorans GW1-1T (96.9 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain JLT21T clustered with Y. aromativorans GW1-1T. The predominant respiratory quinone of strain JLT21T was menaquinone-6 (MK-6). Polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, three unidentified glycolipids and four unidentified lipids. The major fatty acids of strain JLT21T were iso-C15 : 0 (21.7 %), C16 : 1 ω6c/ω7c (11.5 %) and iso-C17 : 0 3-OH (10.9 %). The DNA G+C content of strain JLT21T was 32.6 %. On the basis of polyphasic analysis, strain JLT21T is considered to represent a novel species of the genus Yeosuana, for which the name Yeosuana marina sp. nov. is proposed. The type strain of Yeosuana marina is JLT21T (=CGMCC 1.15787T=JCM 31511T). The study helps us better understand the bacterial species in the shallow-sea hydrothermal system and their adaptations to the hydrothermal environment.

Serinicoccus hydrothermalis sp. nov., isolated from shallow-sea hydrothermal systems off Kueishantao Island.

A Gram-stain-positive, non-flagellated, non-gliding, coccoid bacterial strain, designated JLT9T, was isolated from the shallow-sea hydrothermal system off Kueishantao Island, Taiwan, ROC. Strain JLT9T was aerobic, chemoheterotrophic and grew optimally at 35 °C, at pH 6.0 and in the presence of 2.5 % (w/v) NaCl. Strain JLT9T exhibited highest 16S rRNA gene sequence similarity to Serinicoccus marinus DSM 15273T (98.83 %). Phylogenetic trees based on 16S rRNA gene sequences revealed that strain JLT9T belonged to the genus Serinicoccus, clustering with Serinicoccus marinus JC1078T, Serinicoccus profundi MCCC 1A05965T, Serinicoccus sediminis GP-T3-3T and Serinicoccus chungangensis CAU9536T. The digital DNA-DNA genome hybridization values between strain JLT9T and the closest related strain S. marinus DSM 15273T was 34.30 %. The DNA G+C content was 72.43 mol%. The dominant fatty acids were identified as iso-C15 : 0 (41.4 %) and iso-C16 : 0 (24.7 %). The polar lipids of strain JLT9T comprised diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, three unidentified glycolipid and an unidentified phospholipid. The predominant isoprenoid quinone was MK-8 (H4). The cell wall contained ornithine and serine, and no diaminopimelic acid. On the basis of phylogenetic data and several distinct phenotypic characteristics, strain JLT9T represents a novel species of the genus Serinicoccus, for which the name Serinicoccus hydrothermalis sp. nov. is proposed. The type strain is JLT9T (=CGMCC 1.15779T=JCM 31502T).

Paracoccus aurantiacus sp. nov., isolated from shallow-sea hydrothermal systems off Kueishantao Island.

An orange-pigmented, short-rod-shaped, aerobic and non-motile bacterial strain, designated TK008T, was isolated from the shallow-sea hydrothermal systems off Kueishantao Island in Taiwan, China, and it was studied by using a polyphasic taxonomic approach. Cells were Gram-stain-negative, and catalase- and oxidase-positive. Strain TK008T exhibited highest 16S rRNA gene sequence similarity of 97.1 % to Paracoccus pacificus F14T. The phylogenetic trees based on 16S rRNA gene sequences showed that strain TK008T was a member of the genus Paracoccus. Digital DNA-DNA hybridization values between strain TK008T and two closely related species (Paracoccus zhejiangensis and Paracoccus tegillarcae) were 20.6 and 20.9 %. The average nucleotide identity values of strain TK008T compared with P. zhejiangensis and P. tegillarcae were 75.2 and 74.6 % respectively. The major isoprenoid quinone was ubiquinone-10. The predominant fatty acids (>10 %) were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unidentified phospholipids, two unidentified lipids and an unidentified glycolipid. The DNA G+C content of strain TK008T from genomic sequence data was 62.54 mol%. On the basis of polyphasic analysis, strain TK008T represents a novel species, for which the name Paracoccus aurantiacus sp. nov. is proposed. The type strain is TK008T (=CGMCC 1.13898T=JCM 33630T).