Roseibium algae sp. nov., isolated from a marine alga (Grateloupia sp.).

A novel Gram-stain-negative, rod-shaped, non-spore-forming, aerobic, motile bacterium with a single polar or subpolar flagellum, designated strain H3510T, was isolated from marine alga collected on sea shore of Yantai, PR China. The organism grew optimally at 28 °C and pH 7.0 and in presence of 3.0 % (w/v) NaCl. The strain exhibited positive catalase activity but negative oxidase and nitrate reduction activities. The predominant cellular fatty acids were C18 : 1 ω7c and/or C18 : 1 ω6c, 11-methyl C18 : 1 ω7c, and C16 : 0. Additionally, the major polar lipids were phosphatidylglycerol, phosphatidylmonomethylethanolamine, diphosphatidylglycerol, and phosphatidylethanolamine; the respiratory quinone was ubiquinone 10 (Q-10). The genomic DNA G+C content of strain H3510T was 54.2%. The novel strain showed the closest relationship with Roseibium polysiphoniae KMM 9699T with 98.2 % 16S rRNA gene sequence similarity. The calculated values for average nucleotide identity and DNA-DNA hybridization between strain H3510T and the phylogenetically related Roseibium species were in the range of 71.3-74.9 % and 13.7-19.9 %, respectively. Based on polyphasic analyses, strain H3510T was identified as representing a novel species of the genus Roseibium, for which the name Roseibium algae sp. nov. is proposed. The type strain is H3510T (=KCTC 8206T=MCCC 1K04325T). The heterologously expressed inositol 2-dehydrogenase gene from strain H3510T displayed high oxidation activity on myo-inositol and showed potential in the production of rare stereoisomers of inositol, such as scyllo-inositol.

Polyphasic Investigation of Aliiroseovarius salicola sp. nov., Isolated from Seawater.

A novel Gram-stain-negative, strictly aerobic, short-rod-shaped, and chemo-organoheterotrophic bacterium, designated KMU-50T, was isolated from seawater gathered from Dadaepo Harbor in South Korea. The microorganism grew at 0-4.0% NaCl concentrations (w/v), pH 6.0-8.0, and 4-37 °C. The 16S rRNA gene sequence-based phylogenetic tree demonstrated that the strain KMU-50T is a novel member of the family Roseobacteraceae and were greatly related to Aliiroseovarius crassostreae CV919-312T with sequence similarity of 98.3%. C18:1 ω7c was the main fatty acid and ubiquinone-10 was the only isoprenoid quinone. The dominant polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, two unidentified phospholipids, an unidentified aminolipid, and an unidentified lipid. The genome size of strain KMU-50T was 3.60 Mbp with a DNA G+C content of 56.0%. The average nucleotide identity (ANI) and average amino acid identity (AAI) values between the genomes of strain KMU-50T and its closely related species were 76.0-81.2% and 62.2-81.5%, respectively. The digital DNA-DNA hybridization (dDDH) value of strain KMU-50T with the strain of A. crassostreae CV919-312T was 25.1%. The genome of the strain KMU-50T showed that it encoded many genes involved in the breakdown of bio-macromolecules, thus showing a high potential as a producer of industrially useful enzymes. Consequently, the strain is described as a new species in the genus Aliiroseovarius, for which the name Aliiroseovarius salicola sp. nov., is proposed with the type strain KMU-50T (= KCCM 90480T = NBRC 115482T).

Description of Roseibium sediminicola sp. nov. Isolated from Sediment of a Tidal Flat on the Yellow Sea Coast.

A Gram-stain-negative, aerobic, rod-shaped, motile, flagellated bacterial strain, designated as CAU 1639T, was isolated from the tidal flat sediment on the Yellow Sea in the Republic of Korea. Growth of the isolate was observed at 20-37 °C, at pH 5.0-10.5 and with 0-7% (w/v) NaCl. The genomic DNA G + C content was 60.8%. Phylogenetic analysis, grounded on 16S rRNA gene sequencing, revealed that strain CAU 1639T was closely related to species within the genus Roseibium. It shared the highest similarity with Roseibium album CECT 5095T, followed by Roseibium aggregatum IAM 12614T and Roseibium salinum Cs25T, with 16S rRNA gene sequence similarity ranging from 98.0-98.4%. It was observed that the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values ranged between 72.5-79.5 and 20.0-22.9%, respectively. The polyphasic taxonomic analysis reveals that strain CAU 1639T represents a novel species in the genus Roseibium with the proposed name Roseibium sediminicola sp. nov. The type strain is CAU 1639T (= KCTC 82430T = MCCC 1K06081T).

Psychromarinibacter sediminicola sp. nov., a novel moderately halophilic, metabolically diverse bacterium isolated from a solar saltern sediment, and comparison between members of family Roseobacteraceae.

Known for its species abundance and evolutionary status complexity, family Roseobacteraceae is an important subject of many studies on the discovery, identification, taxonomic status, and ecological properties of marine bacteria. This study compared and analyzed the phylogenetic, genomic, biochemical, and chemo taxonomical properties of seven species from three genera (Psychromarinibacter, Lutimaribacter, and Maritimibacter) of the family Roseobacteraceae. Moreover, a novel strain, named C21-152T was isolated from solar saltern sediment in Weihai, China. The values of 16S rRNA gene sequence similarity, the average nucleotide identity (ANI), the average amino acid identity (AAI), and the digital DNA-DNA hybridization (dDDH) between genomes of the novel strain and Psychromarinibacter halotolerans MCCC 1K03203T were 97.19, 78.49, 73.45, and 21.90%, respectively. Genome sequencing of strain C21-152T revealed a complete Sox enzyme system related to thiosulfate oxidization as well as a complete pathway for the final conversion of hydroxyproline to α-ketoglutarate. In addition, strain C21-152T was resistant to many antibiotics and had the ability to survive below 13% salinity. This strain had versatile survival strategies in saline environments including salt-in, compatible solute production and compatible solute transport. Some of its physiological features enriched and complemented the knowledge of the characteristics of the genus Psychromarinibacter. Optimum growth of strain C21-152T occurred at 37 â„ƒ, with 5-6% (w/v) NaCl and at pH 7.5. According to the results of the phenotypic, chemotaxonomic characterization, phylogenetic properties and genome analysis, strain C21-152T should represent a novel specie of the genus Psychromarinibacter, for which the name Psychromarinibacter sediminicola sp. nov. is proposed. The type strain is C21-152T (= MCCC 1H00808T = KCTC 92746T = SDUM1063002T).

Roseovarius pelagicus sp. nov., a facultatively anaerobic bacterium with potential for degrading polypropylene, isolated from Arctic seawater.

A Gram-stain-negative, facultatively anaerobic, non-motile, rod-shaped bacterial strain, designated HL-MP18T, was isolated from Arctic seawater after a prolonged incubation employing polypropylene as the sole carbon source. Phylogenetic analyses of the 16S rRNA gene sequence revealed that strain HL-MP18T was affiliated to the genus Roseovarius with close relatives Roseovarius carneus LXJ103T (96.8 %) and Roseovarius litorisediminis KCTC 32327T (96.5 %). The complete genome sequence of strain HL-MP18T comprised a circular chromosome of 3.86 Mbp and two circular plasmids of 0.17 and 0.24 Mbp. Genomic comparisons based on average nucleotide identity and digital DNA-DNA hybridization showed that strain HL-MP18T was consistently discriminated from its closely related taxa in the genus Roseovarius. Strain HL-MP18T showed optimal growth at 25 °C, pH 7.0 and 2.5 % (w/v) sea salts. The major cellular fatty acids were C18 : 1 ω6c and/or C18 : 1 ω7c (49.6 %), C19 : 0 cyclo ω8c (13.5 %), and C16 : 0 (12.8 %). The major respiratory quinone was ubiquinone-10. The polar lipids consisted of phosphatidylcholine, phosphatidylglycerol, an unidentified aminolipid and three unidentified lipids. The genomic DNA G+C content of the strain was 59.2 mol%. The phylogenetic, genomic, phenotypic and chemotaxonomic results indicate that strain HL-MP18T is distinguishable from the recognized species of the genus Roseovarius. Therefore, we propose that strain HL-MP18T represents a novel species belonging to the genus Roseovarius, for which the name Roseovarius pelagicus sp. nov. is proposed. The type strain is HL-MP18T (=KCCM 90405T=JCM 35639T).

Limimaricola litoreus sp. nov., isolated from intertidal sand of the Yellow Sea.

A novel species of the genus Limimaricola, designated ASW11-118T, was isolated from an intertidal sand sample of the Yellow Sea, PR China. Growth of strain ASW11-118T occurred at 10-40 °C (optimum, 28 °C), pH 5.5-8.5 (optimum, pH 7.5) and with 0.5-8.0 % (w/v) NaCl (optimum, 1.5%). Strain ASW11-118T has the highest 16S rRNA gene sequence similarity to Limimaricola cinnabarinus LL-001T (98.8%) and 98.6 % to Limimaricola hongkongensis DSM 17492T. Phylogenetic analysis based on genomic sequences indicated that strain ASW11-118T belongs to the genus Limimaricola. The genome size of strain ASW11-118T was 3.8 Mb and DNA G+C content was 67.8 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain ASW11-118T and other members of the genus Limimaricola were below 86.6 and 31.3 %, respectively. The predominant respiratory quinone was ubiquinone-10. The predominant cellular fatty acid was C18 : 1 ω7c. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine and one unknown aminolipid. On the basis of the data presented, strain ASW11-118T is considered to represent a novel species of the genus Limimaricola, for which the name Limimaricola litoreus sp. nov. is proposed. The type strain is ASW11-118T (=MCCC 1K05581T=KCTC 82494T).

Szabonella alba gen. nov., sp. nov., a motile alkaliphilic bacterium of the family Rhodobacteraceae isolated from a soda lake.

A Gram-stain-negative, oxidase- and catalase-positive, rod-shaped, creamy white coloured bacterial strain, DMG-N-6T, was isolated from a water sample of Lake Ferto/Neusiedler See (Hungary). Phylogenetic analysis based on 16S rRNA gene sequences revealed that the strain forms a distinct linage within the family Rhodobacteraceae. Its closest relatives are Tabrizicola alkalilacus DJCT (96.76% similarity) and Tabrizicola piscis K13M18T (96.76%), followed by Tabrizicola sediminis DRYC-M-16T (96.69 %), Rhodobacter sediminicola JA983T (96.62 %), Tabrizicola aquatica RCRI19T (96.47 %) and Cereibacter johrii JA192T (96.18 %). The novel bacterial strain favours an alkaline environment (pH 8.0-12.0) and grows optimally at 18-28°C in the presence of 2-4 % (w/v) NaCl. Cells of DMG-N-6T were motile by a single subpolar flagellum. Bacteriochlorophyll a was not detected. The predominant respiratory quinone was ubiquinone Q-10. The major cellular fatty acid was C18:1 ω7c. The polar lipid profile comprised phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylserine, phosphatidylcholine, an unidentified phospholipid and five unidentified lipids. The assembled draft genome of strain DMG-N-6T had 52 contigs with a total length of 4 219 778 bp and a G+C content of 64.3 mol%. Overall genome-related indices (ANI <77.8 %, AAI <69.0 %, dDDH <19.6 %) with respect to close relatives were all significantly below the corresponding threshold to demarcate bacterial genus and species. Strain DMG-N-6T (=DSM 108208T=NCAIM B.02645T) is strongly different from its closest relatives and is suggested as the type strain of a novel species of a new genus in the family Rhodobacteraceae, for which the name Szabonella alba gen. nov., sp. nov. is proposed.

Structure and ion-release mechanism of PIB-4-type ATPases.

Transition metals, such as zinc, are essential micronutrients in all organisms, but also highly toxic in excessive amounts. Heavy-metal transporting P-type (PIB) ATPases are crucial for homeostasis, conferring cellular detoxification and redistribution through transport of these ions across cellular membranes. No structural information is available for the PIB-4-ATPases, the subclass with the broadest cargo scope, and hence even their topology remains elusive. Here, we present structures and complementary functional analyses of an archetypal PIB-4-ATPase, sCoaT from Sulfitobacter sp. NAS14-1. The data disclose the architecture, devoid of classical so-called heavy-metal-binding domains (HMBDs), and provide fundamentally new insights into the mechanism and diversity of heavy-metal transporters. We reveal several novel P-type ATPase features, including a dual role in heavy-metal release and as an internal counter ion of an invariant histidine. We also establish that the turnover of PIB-ATPases is potassium independent, contrasting to many other P-type ATPases. Combined with new inhibitory compounds, our results open up for efforts in for example drug discovery, since PIB-4-ATPases function as virulence factors in many pathogens.

Heavy metals such as zinc and cobalt are toxic at high levels, yet most organisms need tiny amounts for their cells to work properly. As a result, proteins studded through the cell membrane act as gatekeepers to finetune import and export. These proteins are central to health and disease; their defect can lead to fatal illnesses in humans, and they also help bacteria infect other organisms. Despite their importance, little is known about some of these metal-export proteins. This is particularly the case for P_IB-4-ATPases, a subclass found in plants and bacteria and which includes, for example, a metal transporter required for bacteria to cause tuberculosis. Intricate knowledge of the three-dimensional structure of these proteins would help to understand how they select metals, shuttle the compounds in and out of cells, and are controlled by other cellular processes. To reveal this three-dimensional organisation, Grønberg et al. used X-ray diffraction, where high-energy radiation is passed through crystals of protein to reveal the positions of atoms. They focused on a type of PIB-4-ATPases found in bacteria as an example. The work showed that the protein does not contain the metal-binding regions seen in other classes of metal exporters; however, it sports unique features that are crucial for metal transport such as an adapted pathway for the transport of zinc and cobalt across the membrane. In addition, Grønberg et al. tested thousands of compounds to see if they could block the activity of the protein, identifying two that could kill bacteria. This better understanding of how PIB-4-ATPases work could help to engineer plants capable of removing heavy metals from contaminated soils, as well as uncover new compounds to be used as antibiotics.

Paenihalocynthiibacter styelae gen. nov., sp. nov., isolated from stalked sea squirt Styela clava.

A Gram-stain-negative, strictly aerobic, non-motile and rod-shaped bacterial strain, MYP1-1T, was isolated from the intestine of a stalked sea squirt (Styela clava) of the South Sea in the Republic of Korea. The neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain MYP1-1T clustered with the type strains of Halocynthiibacter species and Pseudohalocynthiibacter aestuariivivens. Strain MYP1-1T exhibited 16S rRNA gene sequence similarity values of 97.0-97.6 % to the type strains of Halocynthiibacter namhaensis, Halocynthiibacter arcticus and P. aestuariivivens. The phylogenetic tree based on genomic sequences showed that strain MYP1-1T formed a distinct branch separating it from the type strains of two Halocynthiibacter species and P. aestuariivivens and other taxa. The DNA G+C content of strain MYP1-1T from its genomic sequence was 55.0 mol%. Strain MYP1-1T contained Q-10 as the predominant ubiquinone and C18 : 1 ω7c as the major fatty acid. The major polar lipids of strain MYP1-1T were phosphatidylcholine, phosphatidylglycerol, one unidentified lipid and one unidentified aminolipid. The differences in fatty acid and polar lipid profiles and other differential phenotypic properties made it reasonable to distinguish strain MYP1-1T from the genera Halocynthiibacter and Pseudohalocynthiibacter. On the basis of the polyphasic taxonomic investigations, we conclude that strain MYP1-1T constitutes a new genus and species within the class Alphaproteobacteria, for which the name Paenihalocynthiibacter styelae gen. nov., sp. nov. is proposed. The type strain is MYP1-1T (=KCTC 82143T=NBRC 114355T).

Cochlodiniinecator piscidefendens gen. nov., sp. nov., an algicidal bacterium against the ichthyotoxic dinoflagellate Cochlodinium polykrikoides.

Harmful algal blooms caused by Cochlodinium polykrikoides result in enormous economic damage to the aquaculture industry. Biological control methods have attracted wide attention due to their environmental-friendliness. In this study, a novel algicidal bacterium, designated strain M26A2MT, was determined for its taxonomic position and was evaluated for its potential to mitigate C. polykrikoides blooms. Strain M26A2MT exhibited the highest 16S rRNA gene sequence similarity to the type strains of Planktotalea lamellibrachiae (97.3%), Halocynthiibacter namhaensis (97.2%), Pseudohalocynthiibacter aestuariivivens (96.8%) and Halocynthiibacter arcticus (96.4%) in the family Rhodobacteraceae. The predominant fatty acids were C10 : 0 3-OH and summed feature 8 (comprising C18 : 1 ω7c and/or C18 : 1 ω6c). The major polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid and three unidentified lipids. Q-10 was the respiratory quinone. Strain M26A2MT exerted significant algicidal activity against C. polykrikoides cells by destroying the membrane integrity and the photosynthetic system. Our findings suggest that strain M26A2MT shows a high potential to control outbreaks of C. polykrikoides. Based on the polyphasic characterization, strain M26A2MT is considered to represent a novel species within a novel genus of the family Rhodobacteraceae, for which the name Cochlodiniinecator piscidefendens gen. nov., sp. nov. is proposed. The type strain is M26A2MT (=KCTC 82083T=JCM 34119T).

Mangrovicoccus algicola sp. nov., an alginate lyase - producing marine bacterium.

A Gram-stain-negative, non-motile, ellipsoid bacterium, designated HB182678T, was isolated from brown alga collected from Hainan province, PR China. Growth was observed at 10-50 °C (optimum 37-40 °C), at pH 6-10 (optimum pH 8) and in the presence of 0.5-13% (w/v) NaCl (optimum, 2-4%). The predominant isoprenoid quinone was Q-10 and the major fatty acids were C18 : 1 ω7c, C16 : 0, C18 : 0 and C19 : 0 cyclo ω8c. The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, an unidentified phospholipid, two unidentified glycolipids and three unidentified aminophospholipids. The size of the draft genome was 4.40 Mbp with G+C content 68.8 mol%. Phylogenetic analysis of 16S rRNA gene sequence indicated that strain HB182678T belonged to the genus Mangrovicoccus, and the closest phylogenetically related species was Mangrovicoccus ximenensis T1lg56T (with the similarity of 96.3%). Whole genome average nucleotide identity (ANI) value between them was 84.3% and in silico DNA-DNA hybridization value was 27.2%. The combined phylogenetic relatedness, phenotypic and genotypic features supported the conclusion that strain HB182678T represents a novel species of the genus Mangrovicoccus, for which the name Mangrovicoccus algicola sp. nov. is proposed. The type strain is HB182678T (=MCCC 1K04624T=KCTC 82318T).

Palleronia sediminis sp. nov. and Flavivirga algicola sp. nov., two marine bacteria isolated from offshore areas near Weihai.

Two bacterial strains, designated SS33T and Y03T, were isolated from marine sediment and marine red alga collected on the coast of Weihai, PR China. Based on the results of 16S rRNA gene sequence analysis, strain SS33T was found to be closely related to Primorskyibacter marinus PX7T, Pelagivirga dicentrarchi YLY04T, Palleronia marisminoris DSM 26347T and Maribius pontilimi GH1-23T with 94.8, 94.6, 94.5 and 94.5 % sequence similarity; strain Y03T was found to be closest to Flavivirga aquimarina EC2D5T, Flavivirga eckloniae ECD14T and Flavivirga amylovorans JC2681T with 96.4, 96.1 and 96.0 % sequence similarity. Strain SS33T grew at 4-37 °C (optimum, 33 °C), at pH 6.0-9.5 (optimum, pH 7.5-8.0) and in the presence of 0-10 % (w/v) NaCl (optimum, 3.0 %). Chemotaxonomic analysis of strain SS33T showed that the predominant respiratory quinone was ubiquinone-10. The major fatty acids (>10.0 %) included C18 : 1 ω7c and C16 : 0. The major polar lipids included phosphatidylglycerol, phosphatidylcholine, one unidentified phospholipid, one unidentified glycolipid, one unidentified polar lipid and two unidentified aminolipids. Strain Y03T grew at 15-40 °C (optimum, 28 °C), at pH 6.5-8.0 (optimum, pH 7.0) and in the presence of 0.5-9.0 % (w/v) NaCl (optimum, 2.0%). Chemotaxonomic analysis showed that the predominant respiratory quinone was menaquinone-6. The major fatty acids (>10.0 %) included iso-C15 : 0, iso-C15 : 1 G, iso-C17 : 0 3-OH and iso-C15 : 0 3-OH. The major polar lipids included phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminolipid and four unidentified polar lipids. Based on the polyphasic data, strain SS33T is considered to represent a novel species of the genus Palleronia, for which the name Palleronia sediminis sp. nov. is proposed, with the type strain SS33T (=KCTC 62986T=MCCC 1H00387T). Strain Y03T is considered to represent a novel species of the genus Flavivirga, for which the name Flavivirga algicola sp. nov. is proposed, with the type strain Y03T (=KCTC 72001T=MCCC 1H00386T).

Salipiger mangrovisoli sp. nov., isolated from mangrove soil and the proposal for the reclassification of Paraphaeobacter pallidus as Salipiger pallidus comb. nov.

A novel Gram-stain-negative, aerobic and rod-shaped bacterial strain designated as 6D45AT was isolated from mangrove soil and characterized using a polyphasic taxonomic approach. Strain 6D45AT was found to grow at 10-37 °C (optimum, 28 °C), at pH 6.0-9.0 (optimum, 7.0) and in 0-5 % (w/v) NaCl (optimum, 2%). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 6D45AT fell into the genus Salipiger and shared 99.1 % identity with the closest type strain Salipiger pacificus CGMCC 1.3455T and less than 97.2 % identity with other type strains of this genus. The 34.8 % digital DNA-DNA hybridization (dDDH) and 88.3 % average nucleotide identity (ANI) values between strain 6D45AT and the closest relative above were well below recognized thresholds of 70 % DDH and 95-96 % ANI for species definition, implying that strain 6D45AT should represent a novel genospecies. The phylogenomic analysis indicated that strain 6D45AT formed an independent branch distinct from reference strains. The predominant cellular fatty acid of strain 6D45AT was summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c, 66.9 %); the polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, two unidentified aminolipids, two unidentified glycolipids and an unknown lipid; the respiratory quinone was Q-10. The genomic DNA G+C content was 66.5 mol %. Based on the phenotypic and genotypic characteristics, strain 6D45AT is concluded to represent a novel species of the genus Salipiger, for which the name Salipiger mangrovisoli sp. nov., is proposed. The type strain of the species is 6D45AT (=GDMCC 1.1960T=KCTC 82334T). We also propose the reclassification of Paraphaeobacter pallidus as Salipiger pallidus comb. nov. and 'Pelagibaca abyssi' as a species of the genus Salipiger.

Muriiphilus fusiformis gen. nov., sp. nov., a novel non-marine bacterium belonging to the Roseobacter group, and reclassification of Maritimibacter lacisalsi (Zhong et al. 2015) as Muriicola lacisalsi gen. nov., comb. nov.

An aerobic, Gram-stain-negative, non-sporulating, flagellated and spindle-like bacterium, designated HY14T, was isolated from a pickle-processing factory wastewater sample. The isolate chemoheterotrophically grew at 4-42 °C (optimum, 35 °C) and pH 5.5-9.0 (optimum, pH 6.0-6.5). Salt was required for growth (0.5-12 % NaCl, w/v). A deep brown and water-soluble uncharacterized pigment was produced when grown in certain media. The predominant fatty acids (>5 %) included C16 : 0, C18 : 1 ω7c, 11-methyl C18 : 1 ω7c and C19 : 0 cyclo ω8c. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, two unidentified aminolipids, two unidentified phospholipids, two unidentified glycolipids and five unknown lipids. The major isoprenoid quinone was ubiquinone-10. Pairwise alignment based on 16S rRNA gene sequences indicated that strain HY14T had the highest sequence similarity to genera Maritimibacter (95.61-96.05 %) and Boseongicola (95.82 %). Phylogenetic analysis based on core genome illustrated that strain HY14T formed a monophyletic lineage with members of the genus Maritimibacter in the clade of the Roseobacter group in the family Rhodobacteraeceae. The core-gene average amino acid identity used to define bacterial genera by a threshold of 60-80 % was calculated to be 68.56-76.5 % between HY14T and closely related taxa. Several genomic characteristics, such as carrying two RuBisCO-mediated pathways and different osmoprotectant transport pathways, exhibited the genotypic discrepancies of strain HY14T. Based on the polyphasic taxonomic characterization, strain HY14T is considered to represent a novel species of a novel genus belonging to the family Rhodobacteraeceae, for which the name Muriiphilus fusiformis gen. nov., sp. nov. is proposed. The type strain is HY14T (=CGMCC 1.15973T=KCTC 52499T). Maritimibacter lacisalsi (Zhong et al. 2015) is considered to diverge from Maritimibacter alkaliphilus at the genus level, and should be reassigned as a novel genus, for which the name Muriicola lacisalsi gen. nov., comb. nov. is proposed.

Sulfitobacter aestuariivivens sp. nov., isolated from a tidal flat.

A Gram-stain-negative, aerobic, non-flagellated, coccoid, ovoid or rod-shaped bacterial strain, TSTF-M16T, was isolated from a tidal flat on the Yellow Sea, Republic of Korea. The neighbour-joining phylogenetic tree of 16S rRNA gene sequences showed that strain TSTF-M16T fell within a clade comprising the type strains of Sulfitobacter species. Strain TSTF-M16T exhibited 16S rRNA gene sequence similarities of 98.5 and 98.1 % to the type strains of Sulfitobacter mediterraneus and Sulfitobacter sabulilitoris, respectively, and 96.2-97.8 % to the type strains of the other Sulfitobacter species. The average nucleotide identity and digital DNA-DNA hybridization values between the genomic sequences of strain TSTF-M16T and the type strains of 16 Sulfitobacter species were 70.6-74.2 and 17.9-19.0 %, respectively. The DNA G+C content of strain TSTF-M16T from genomic sequence data was 59.26 mol%. Strain TSTF-M16T contained Q-10 as the predominant ubiquinone and C18 : 1 ω7c as the major fatty acid. The major polar lipids of strain TSTF-M16T were phosphatidylcholine, phosphatidylglycerol, one unidentified aminolipid and one unidentified lipid. Distinguished phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain TSTF-M16T is separated from recognized Sulfitobacter species. On the basis of the data presented here, strain TSTF-M16T is considered to represent a novel species of the genus Sulfitobacter, for which the name Sulfitobacter aestuariivivens sp. nov. is proposed. The type strain is TSTF-M16T (=KACC 21645T=NBRC 114501T).

Stappia albiluteola sp. nov., isolated from marine sediment.

A Gram-stain negative, rod-shaped, facultatively aerobic, pale-beige-coloured bacterial strain, designated F7233T, was isolated from coastal sediment sampled at Jingzi Bay, Weihai, PR China. Cells of strain F7233T were 0.3-0.4 µm wide, 1.2-1.4 µm wide long, non-spore-forming and motile with one flagellum. Optimum growth occurred at 30 °C, with 1.0 % (w/v) NaCl and at pH 6.5-7.0. Positive for nitrate reduction, hydrolysis of Tweens and oxidase activity. The sole respiratory quinone of strain F7233T was ubiquinone-10 and the predominant cellular fatty acid was summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c). The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and one unidentified aminophospholipid. The G+C content of the chromosomal DNA was 63.3 mol%. Phylogenetic analysis of the 16S rRNA gene sequence revealed that the newly isolate belonged to the genus Stappia, with 96.8 % sequence similarity to Stappia indica MCCC 1A01226T, 96.1 % similarity to Stappia stellulata JCM 20692T and 95.5% similarity to Stappia taiwanensis CC-SPIO-10-1T. On the basis of phylogenetic, phenotypic and chemotaxonomic data, it is considered that strain F7233T should represent a novel species within the genus Stappia, for which the name Stappia albiluteola sp. nov. is proposed. The type strain is F7233T (=MCCC 1H00419T=KCTC 72859T).

Pikeienuella piscinae gen. nov., sp. nov., a novel genus in the family Rhodobacteraceae.

A novel bacterium, designated strain RR4-56T, was isolated from a biofilter of a seawater recirculating aquaculture system. The 16S rRNA gene sequence analysis showed that the isolate was closely related to Halovulum dunhuangense YYQ-30T (92.6%), Albimonas donghaensis DS2T (91.3%), Pontivivens insulae GYSW-23T (91.3%), and Monaibacterium marinum C7T (90.9%), belonging to the family Rhodobacteraceae. The strain was aerobic, Gram-negative, rod-shaped, oxidase-positive, and catalase-negative. Its optimum temperature, pH, and salinity for growth were 25-30°C, pH 8.5, and 2-3% NaCl (w/v), respectively. Its growth occurred at 15-35°C, pH 5.0-9.5, and 0-7% NaCl (w/v). It contained ubiquinone-10 (Q-10), a respiratory quinone, and the major cellular fatty acids were 11-methyl C18:1 ω7c (31.9%), C18:1 ω6c (30.4%), and C19:0 cyclo ω8c (16.1%). The polar lipids present in the strain were phosphatidylglycerol, an unidentified phospholipid, and an unidentified aminolipid. The strain had one 4,373,045 bp circular chromosome with G + C contents of 65.9 mol% including 4,169 genes, 4,118 coding sequences (CDSs), 3 rRNAs, and 45 tRNAs. Genome annotation predicted some gene clusters related to the degradation of several types of organic matter such as protocatechuate, catechol, and phthalate. Based on the polyphasic characteristics, RR4-56T represents a novel genus and species in the family Rhodobacteraceae, for which the name Pikeienuella piscinae gen. nov., sp. nov. was proposed. The type strain is RR4-56T (= KCTC 52648T = DSM 107918T).

Combined characterization of a new member of Marivita cryptomonadis strain LZ-15-2 isolated from cultivable phycosphere microbiota of highly toxic HAB dinoflagellate Alexandrium catenella LZT09.

During our conveying the microbial structures of phycosphere microbiota (PM) derived from diverse marine harmful algal bloom (HAB) dinoflagellates, a new rod-sharped, white-colored cultivable bacterial strain, designated as LZ-15-2, was isolated from the PM of highly toxic Alexandrium catenella LZT09. Phylogenetic analysis of 16S rRNA gene sequence indicated that strain LZ-15-2 belonged to the genus Marivita within the family Rhodobacteraceae, and demonstrated the highest gene similarity of 99.2% to M. cryptomonadis CL-SK44T, and less than 98.65% with other type strains of Marivita. Phylogenomic calculations on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the new isolate and M. cryptomonadis CL-SK44T were 99.86% and 99.88%, respectively. Genomic comparison of strain LZ-15-2 with available genomes of Marivita species further verified its taxonomic position within the genus of Marivita. Moreover, comparative genomics analysis showed a proximal similarity of strain LZ-15-2 with M. cryptomonadis CL-SK44T, and it also revealed an open pan-genome status based on constructed gene accumulation curves among Marivita members with 9,361 and 1,712 genes for the pan- and core-genome analysis, respectively. Based on combined polyphasic taxonomic characteristics, strain LZ-15-2 represents a new member of M. cryptomonadis, and proposed as a potential candidate for further exploration of the detailed mechanisms governing the dynamic cross-kingdom algae-bacteria interactions (ABI) between PM and their algal host LZT09.

Sulfitobacter algicola sp. nov., isolated from green algae.

A novel Gram-stain-negative, aerobic, non-flagellated, non-motile, oval-rod-shaped and light pink to light tawny-pigmented bacterial strain (designated 1151T) were isolated from marine green algae obtained from the coastal seawater of Weihai, China. Strain 1151T was found to grow at 15-37 °C (optimum, 33 °C), pH 7.0-9.5 (optimum, 7.5-8.5) and in the presence of 1-6% (w/v) NaCl (optimum, 3%). Cells were oxidase-positive and catalase-positive. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 1151T was a member of the genus Sulfitobacter and exhibited the hightest sequence similarity to Sulfitobacter indolifex DSM 14862T (96.6%), followed by the sequence similarity to Sulfitobacter aestuarii hydD52T (96.5%) and Sulfitobacter profundi SAORIC-263T (96.5%). The average nucleotide identity and digital DDH values between strain 1151T and Sulfitobacter indolifex DSM 14862T were 69.9% and 20.9%, respectively. The average amino acid identity between strain 1151T and Sulfitobacter pontiacus DSM 10014T (type strain of the type species) was 62.3%. Q-10 was detected as the sole respiratory quinone. The dominant cellular fatty acids were sum feature 8 (C18: 1ω7c; 44.1%), C20: 1ω7c (29.7%) and C18: 0 (11.7%). The DNA G + C content of strain 1151T was 51.8 mol%. The polar lipids included phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), and three unidentified lipids (L1, L2 and L3). Based on the phylogenetic and phenotypic characteristics, strain 1151T is considered to represent a novel species of the genus Sulfitobacter, for which the name Sulfitobacter algicola sp. nov. is proposed. The type strain is 1151T (= KCTC 72513T = MCCC 1H00384T).

Roseibium litorale sp. nov., isolated from a tidal flat sediment and proposal for the reclassification of Labrenzia polysiphoniae as Roseibium polysiphoniae comb. nov.

A novel Gram-stain-negative, facultatively anaerobic, rod-shaped and non-motile bacterial strain, designated as 4C16AT, was isolated from a tidal flat sediment and characterized by using a polyphasic taxonomic approach. Strain 4C16AT was found to grow at 10-40 °C (optimum, 28 °C), at pH 5.0-10.0 (optimum, pH 6.0-7.0) and in 0-6 % (w/v) NaCl (optimum, 1 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 4C16AT fell into the genus Roseibium, and shared the highest identity of 98.9 % with the closest type strain Roseibium suaedae KACC 13772T and less than 98.0 % identity with other type strains of recognized species within this genus. The phylogenomic analysis indicated that strain 4C16AT formed an independent branch within this genus. The 28.6 % digital DNA-DNA hybridization estimate and 85.0 % average nucleotide identity between strains 4C16AT and R. suaedae KACC 13772T were the highest, but still far below their respective threshold for species definition, implying that strain 4C16AT should represent a novel genospecies. The predominant cellular fatty acid was summed feature 8; the polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylmonomethylethanolamine; the respiratory quinones were Q-9 and Q-10. The genomic DNA G+C content was 59.8mol %. Based on phylogenetic analyses and phenotypic and chemotaxonomic characteristics, strain 4C16AT is concluded to represent a novel species of the genus Roseibium, for which the name Roseibium litorale sp. nov. is proposed. The type strain of the species is 4C16AT (=GDMCC 1.1932T=KACC 22078T). We also propose the reclassification of Labrenzia polysiphoniae as Roseibium polysiphoniae comb. nov. and 'Labrenzia callyspongiae' as Roseibium callyspongiae sp. nov.