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.

Succession and environmental response of sediment bacterial communities in the Liao River Estuary at the centenary scale

Microbial community succession in turbulent estuarine environments is key to the understanding of microbial community development in estuaries. Centennial-scale sediment core samples collected from the Liao River Estuary (LRE) channel bar and side beaches were studied for geochemistry and 16S rRNA gene-based bacterial analyses. The results showed that bacterial community composition significantly differed between the sediments of the two sides of the channel bar, with Campilobacterota and Bacteroidota being dominant bacterial phyla in the tributary (T1, T2) and mainstream (MS1, MS2) sediment, respectively. Co-occurrence network of the bacterial community at the genus level showed more centralized and compacted topological features in tributary with weaker hydrodynamic, and the keystone taxas were Halioglobus, Luteolibacter, and Lutibacter in the bacterial community. The bacterial network structure had more edges and larger average degree in LRE sediments from the stage of the year 2016-2009 and the stage before 1939, which was possibly related to hydrodynamic conditions and nutrients. Stochastic processes (dispersal limitation) were the key factors driving bacterial community assembly in the LRE sediments. In addition, total organic carbon (TOC), total sulfur (TS), and grain size were the main deterministic factors affecting the change of bacterial community structure. Relative microbial abundance has the potential to indicate geologically historical environmental changes. This study provided a new perspective to reveal the succession and response of bacterial communities under frequent fluctuation environments.

Dasania phycosphaerae sp. nov., isolated from phytoplankton sample from the south coast of the Republic of Korea

A novel bacterial strain, designated as GY-18T, was isolated from particulate material sampled from the Korean south coast. The bacterium was Gram-stain-negative, aerobic and rod-shaped. Oxidase and catalase were positive. Optimal growth was observed at 30 °C, pH 7.0, in the presence of 1 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene and whole-genome sequences suggested that strain GY-18T was a member of the genus Dasania , but represented a separate lineage. The 16S rRNA gene sequence of strain GY-18T showed high similarities to Dasania marina KCTC 12566T (98.4 %), Halioglobus japonicus KCTC 23429T (92.2 %), Marimicrobium arenosum KCTC 42300T (92.4 %) and Seongchinamella unica KCTC 62383T (92.2 %), respectively. The genome length of strain GY-18T was 3 808 450 bp with a DNA G+C content of 47.8 mol %. The major cellular fatty acids of strain GY-18T were summed feature 3 (comprising C16 : 1  ω7c and/or C16 : 1  ω6c), C16 : 0 and C10 : 0 3-OH (>10 %). Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phospholipids were shown to be the major polar lipids. The predominant isoprenoid quinone was Q-8. Based on phylogenetic, phenotypic, chemotaxonomic and genomic features, we propose that strain GY-18T represents a novel species in the genus Dasania of the family Spongiibacteraceae , with the proposed name Dasania phycosphaerae sp. nov. The type strain is GY-18T (=KCTC 92290T=GDMCC 1.3586T).

Pseudohalioglobus sediminis sp. nov., isolated from coastal sediment

A Gram-stain-negative, strictly aerobic, non-motile and rod-shaped bacterial strain, designated NY5^T, was isolated from marine sediment collected from coastal area in Weihai, China (122°07' 38.80'' E, 37°33' 57.60'' N). Cells of strain NY5^T were 0.6-0.7 μm width and 1.9-2.0 μm length, catalase-positive and oxidase-positive. Growth of NY5^T was observed at 25-37 °C (optimum, 28 °C) and pH 6.5-9.5 (optimum, pH 7.5-8.0) and in the presence of 0.5-7.0% (w/v) NaCl (optimum, 2.0%). The isoprenoid quinone was Q-8 and the predominant fatty acids were summed feature 8 (C_18:1 ω7c and/or C_18:1 ω6c), summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c) and C_17:1 ω8c. Diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol were the major polar lipids. The DNA G+C content of strain NY5^T was 60.1%. Strain NY5^T showed the highest 16S rRNA gene sequence similarity (98.2%) with Pseudohalioglobus lutimaris followed by Parahaliea aestuarii (96.9%), Parahaliea maris (96.7%), Parahaliea mediterranea (95.9%), and Halioglobus japonicus (94.9%). Given these phenotypic and chemotaxonomic properties and phylogenetic analyses, strain NY5^T was considered to represent a novel species of the genus Pseudohalioglobus, for which the name Pseudohalioglobus sediminis sp. nov. is proposed. The type strain is NY5^T (=KCTC 72416^T=MCCC 1H00401^T).

Maribrevibacterium harenarium gen. nov., sp. nov., represented by a marine strain of the family Oceanospirillaceae

A Gram-stain-negative, non-motile, facultatively anaerobic, short rod-shaped bacterium, designated HB171799^T, was isolated from seacoast sandy soil collected at Qishui Bay, Hainan, PR China. The chemotaxonomic analysis revealed that the respiratory quinones were Q-8 and Q-7, and the major cellular fatty acids were summed feature 8 (comprising C_18 : 1  ω7c and/or C_18 : 1  ω6c), C_16 : 0 and C_18 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified phospholipid and an unidentified lipid. The size of the draft genome was 3.68 Mb with a DNA G+C content of 48.0 mol%. Results of phylogenetic analyses based on 16S rRNA gene and genome sequences showed that the novel isolate belonged to the family Oceanospirillaceae and formed a distinct subcluster at the base of the radiation of the genus Marinomonas. The highest sequence similarity (96.0 %) of the novel isolate was found to the type strains of Marinomonas fungiae JCM 18476^T and Marinomonas ostreistagni DSM23425^T. The whole genome-based phylogeny and differences in cellular fatty acids and polar lipids readily distinguished strain HB171799^T from all the closely related validly published type strains. Strain HB171799^T is therefore suggested to represent a novel species of a new genus in the family Oceanospirillaceae, for which the name Maribrevibacterium harenarium gen. nov., sp. nov. is proposed. The type strain is HB171799^T (=CGMCC 1.16727^T=JCM 33332^T).

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).

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).