Phylogenomic evaluation of Mangrovimicrobium sediminis gen. nov. sp. nov., the first nitrogen fixing member of the family Halieaceae adapted to mangrove habitat and reclassification of Halioglobus pacificus to Pseudohaliglobus pacificus comb. nov

The taxonomic position and genomic characteristics of a nitrogen fixing and polymer degrading marine bacterium, strain SAOS 164 isolated from a mangrove sediment sample was investigated. Sequence analysis based on 16S rRNA gene identified it as a member of family Halieaceae with closest similarity to Haliea salexigens DSM 19537T (96.3 %), H. alexandrii LZ-16-2T (96.2 %) and Parahaliea maris HSLHS9T (96.0 %) but was distantly related to the genera Haliea, Parahaliea and Halioglobus in phylogenetic trees. In order to ascertain the exact taxonomic position, phylogeny based on RpoBC proteins, whole genome, core and orthologous genes, and comparative analysis of metabolic potential retrieved the strain in an independent lineage clustering along with the genera Halioglobus, Pseudohalioglobus and Seongchinamella. Further, various genome based delimitation parameters represented by mol % GC content, percentage of conserved proteins (POCP), and amino acid identity (AAI) along with chemotaxonomic markers (i.e. fatty acids and polar lipids) supported the inferences of genome based phylogeny and indicated that the strain SAOS 164 belongs to a novel genus. The genome was mapped to 4.8 Mb in size with 65.1 % DNA mol% G + C content. In-silico genomic investigation and phenotyping revealed diverse metabolite genes/pathways related to polymer hydrolysis, nitrogen fixation, light induced growth, carbohydrate, sulfur, phosphorus and amino acid metabolism, virulence factors, defense mechanism, and stress-responsive elements facilitating survival in the mangrove habitat. Based on polyphasic taxonomic approach including genome analyses, a novel genus Mangrovimicrobium sediminis gen. nov. sp. nov. (=SAOS 164T = MTCC 12907T = KCTC 52755T = JCM 32136T) is proposed. Additionally, the reclassification of Halioglobus pacificus (=DSM 27932T = KCTC 23430T = S1-72T) to Pseudhalioglobus pacificus comb. nov. is also proposed.

Sediminihaliea albiluteola gen. nov., sp. nov., a new member of the family Halieaceae, isolated from marine sediment

A Gram-stain-negative, rod-shaped and facultatively aerobic bacterial strain, designated F7430^T, was isolated from coastal sediment collected at Jingzi Wharf in Weihai, PR China. Cells of strain F7430^T were 0.3-0.4 µm wide, 2.0-2.6 µm long, non-flagellated, non-motile and formed pale-beige colonies. Growth was observed at 4-40 °C (optimum, 30 °C), pH 6.0-9.0 (optimum, pH 7.5-8.0) and at NaCl concentrations of 1.0-10.0 % (w/v; optimum, 1.0 %). The sole respiratory quinone of strain F7430^T was ubiquinone 8 and the predominant cellular fatty acids were summed feature 8 (C_18 : 1  ω7c / C_18 : 1  ω6c; 60.7 %), summed feature 3 (C_16 : 1  ω7c/C_16 : 1  ω6c; 30.2 %) and C_15 : 0 iso (13.9 %). The polar lipids of strain F7430^T consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, one unidentified phospholipid and three unidentified lipids. Results of 16S rRNA gene sequences analyses indicated that this strain belonged to the family Halieaceae and had high sequence similarities to Parahaliea aestuarii JCM 51547^T (95.3 %) and Halioglobus pacificus DSM 27932^T (95.2 %) followed by 92.9-95.0 % sequence similarities to other type species within the aforementioned family. The rpoB gene sequences analyses indicated that the novel strain had the highest sequence similarities to Parahaliea aestuarii JCM 51547^T (82.2 %) and Parahaliea mediterranea DSM 21924^T (82.2 %) followed by 75.2-80.5 % sequence similarities to other type species within this family. Phylogenetic analyses showed that strain F7430^T constituted a monophyletic branch clearly separated from the other genera of family Halieaceae. Whole-genome sequencing of strain F7430^T revealed a 3.3 Mbp genome size with a DNA G+C content of 52.6 mol%. The genome encoded diverse metabolic pathways including the Entner-Doudoroff pathway, assimilatory sulphate reduction and biosynthesis of dTDP-l-rhamnose. Based on results from the current polyphasic study, strain F7430^T is proposed to represent a novel species of a new genus within the family Halieaceae, for which the name Sediminihaliea albiluteola gen. nov., sp. nov. is proposed. The type strain of the type species is F7430^T (=KCTC 72873^T=MCCC 1H00420^T).

Kineobactrum salinum sp. nov., isolated from marine sediment

Strain M2^T, isolated from marine sediment collected at Jeju Island, was an aerobic, Gram-stain-negative, oxidase- and catalase-positive, motile, rod-shaped bacterium that formed circular, raised, yellow colonies. Strain M2^T grew at 15-42 °C, pH 5.5-9.0 and with 1-9 % (w/v) NaCl. Phylogenetic analysis based on its 16S rRNA gene sequences indicated that strain M2^T was closely related to Kineobactrum sediminis F02^T (98.0 % sequence similarity). Ubiquinone-8 was determined to be the sole respiratory quinone. Summed feature 3 (C_16 : 1  ω6c/C_16 : 1  ω7c) and summed feature 8 (C_18 : 1  ω7c/C_18 : 1  ω6c) were identified as the predominant fatty acids. The DNA G+C content and digital DNA-DNA relatedness between strain M2^T and K. sediminis F02^T were 60.7 mol% and 19.5 %, respectively. Phosphatidylglycerol and phosphatidylethanolamine were identified as the major polar lipids. Thus, polyphasic characterization revealed that strain M2^T represents a novel species in the genus Kineobactrum, for which the name Kineobactrum salinum sp. nov. is proposed. The type strain is M2^T (=KCTC 72815^T=VTCC 910108^T).

Aequoribacter fuscus gen. nov., sp. nov., a new member of the family Halieaceae, isolated from coastal seawater

A Gram-stain-negative, rod-shaped, obligately aerobic, nonflagellated, and chemoheterotrophic bacterium, designated IMCC3088^T, was isolated from coastal seawater of the Yellow Sea. The 16S rRNA gene sequence analysis indicated that this strain belonged to the family Halieaceae which shared the highest sequence similarities with Luminiphilus syltensis NOR5-1B^T (94.5%) and Halioglobus pacificus S1-72^T (94.5%), followed by 92.3-94.3% sequence similarities with other species within the aforementioned family. Phylogenetic analyses demonstrated that strain IMCC3088^T was robustly clustered with Luminiphilus syltensis NOR5-1B^T within the family Halieaceae. However, average amino acid identity (AAI), percentages of conserved proteins (POCP), average nucleotide identity (ANI), and alignment fraction (AF) between strain IMCC3088^T and Luminiphilus syltensis NOR5-1B^T were 54.5%, 47.7%, 68.0%, and 16.5%, respectively, suggesting that they belonged to different genera. Whole-genome sequencing of strain IMCC3088^T revealed a 3.1 Mbp genome size with a DNA G + C content of 51.7 mol%. The genome encoded diverse metabolic pathways including sulfur oxidation, phenol degradation, and proteorhodopsin phototrophy. Mono-unsaturated fatty acids were found to be the predominant cellular fatty acid components in the strain. Phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol were the primarily identified polar lipids, and ubiquinone-8 was identified as a major respiratory quinone. The taxonomic data collected herein suggested that strain IMCC3088^T represented a novel genus and species of the family Halieaceae, for which the name Aequoribacter fuscus gen. nov., sp. nov. is proposed with the type strain (= KACC 15529^T = NBRC 108213^T).

Halioglobus maricola sp. nov., isolated from coastal seawater

A Gram-stain-negative, rod-shaped, aerobic, non-flagellated, chemoheterotrophic bacterium, designated IMCC14385T, was isolated from surface seawater of the East Sea, Republic of Korea. The 16S rRNA gene sequence analysis indicated that IMCC14385T represented a member of the genus Halioglobus sharing 94.6–97.8 % similarities with species of the genus. Whole-genome sequencing of IMCC14385T revealed a genome size of 4.3 Mbp and DNA G+C content of 56.7 mol%. The genome of IMCC14385T shared an average nucleotide identity of 76.6 % and digital DNA–DNA hybridization value of 21.6 % with the genome of Halioglobus japonicus KCTC 23429T. The genome encoded the complete poly-β-hydroxybutyrate biosynthesis pathway. The strain contained summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and C17 : 1 ω8c as the predominant cellular fatty acids as well as ubiquinone-8 (Q-8) as the respiratory quinone. The polar lipids detected in the strain were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, five unidentified phospholipids, an unidentified aminolipid, an unidentified aminophospholipid and four unidentified lipids. On the basis of taxonomic data obtained in this study, it is suggested that IMCC14385T represents a novel species of the genus Halioglobus , for which the name Halioglobus maricola sp. nov. is proposed. The type strain is IMCC14385T (=KCTC 72520T=NBRC 114072T).