Polaribacter undariae sp. nov., isolated from a brown alga reservoir

Polaribacter uvawellassae sp. nov., a Member of the Family Flavobacteriaceae Isolated from Mud Crab (Scylla serrata)

A Gram-stain-negative, strictly aerobic, rod-shaped, and no flagella, designated SLMDC-22 T, was isolated from the intestine of a mud crab (Scylla serrata). The molecular phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SLMDC-22 T belonged to the genus Polaribacter and exhibited 96.9% similarity to P. huanghezhanensis, 96.5% to P. pacificus, 95.8% to P. lacunae, and 94.1% to P. marinivivus. The G + C content of the DNA of strain SLMDC-22 T was 30.3%. Growth occurred at 4-34 °C (optimum, 23 °C), at pH 5-9 (optimum, pH 7.0), and with 0.5-2.0% (w/v) NaCl (optimum, 2%). The major fatty acid was iso-C15:0. Major polar lipids include phospholipid, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, amino lipid, glycolipid, amino phospholipid, and an unknown polar lipid. The major respiratory quinone is MK-6. Based on whole-genome analysis, the orthologous average nucleotide identity (ANI) with the two closest relatives, Polaribacter huanghezhanensis and Polaribacter pacificus, were 87.3% and 75.7%, respectively. Furthermore, the digital DNA-DNA hybridization (dDDH) values against Polaribacter huanghezhanensis and Polaribacter pacificus were 75.8% and 19.6%, respectively. Notably, 25 genes of SLMDC-22 T were associated with nitrogen metabolism, including denitrification, nitrate ammonification, ammonium assimilation, and nitrosative stress. The phenotypic, genotypic, phylogenetic, and chemotaxonomic data revealed that strain SLMDC-22 T represents a novel species of the genus Polaribacter, for which the name Polaribacter uvawellassae sp. nov. is proposed. The type strain is SLMDC-22 T (= KCTC 102289 T = MCCC 1K09222T).

Polaribacter ponticola sp. nov., isolated from seawater, reclassification of Polaribacter undariae as a later heterotypic synonym of Polaribacter sejongensis, and emended description of Polaribacter sejongensis Kim et al. 2013

A Gram-stain-negative, yellow-pigmented, and strictly aerobic bacterium, designated as strain MSW5T, was isolated from seawater of the Yellow Sea in South Korea. The cells were non-motile rods exhibiting oxidase- and catalase-positive activities. Growth was observed at 15-25 °C (optimum, 25 °C) and pH 5.0-9.0 (optimum, pH 7.0-8.0) and in the presence of 1.0-5.0% (w/v) NaCl (optimum, 2.0%). Menaquinone-6 was the sole respiratory quinone, and iso-C15 : 0, summed feature 3 (C16 : 1  ω7c and/or C16 : 1  ω6c), iso-C15 : 0 3-OH, and C15 : 1  ω6c were the major cellular fatty acids. Major polar lipids included phosphatidylethanolamine, two unidentified aminolipids, and three unidentified lipids. Phylogenetic analyses based on 16S rRNA gene sequences and 92 concatenated core protein sequences revealed that strain MSW5T formed a distinct lineage within the genus Polaribacter. The genome of strain MSW5T was 3582 kb in size with a 29.1 mol% G+C content. Strain MSW5T exhibited the highest similarity to Polaribacter atrinae WP25T, with a 97.9% 16S rRNA gene sequence similarity. However, the average nucleotide identity and digital DNA-DNA hybridization values were 79.4 and 23.3%, respectively, indicating that strain MSW5T represents a novel species. Based on its phenotypic, chemotaxonomic, and phylogenetic characteristics, strain MSW5T is proposed to represent a novel species, with the name Polaribacter ponticola sp. nov. The type strain is MSW5T (=KACC 22340T=NBRC 116025T). In addition, whole genome sequence comparisons and phenotypic features suggested that Polaribacter sejongensis and Polaribacter undariae belong to the same species, with P. undariae proposed as a later heterotypic synonym of P. sejongensis. An emended description of Polaribacter sejongensis is also proposed.

Description of Polaribacter aestuariivivens sp. nov., isolated from a tidal flat

A bacterial strain, DBTF-3T, was isolated from a tidal flat of Republic of Korea. Phylogenetic trees of 16S rRNA gene sequences showed that strain DBTF-3T belonged to the genus Polaribacter. Strain DBTF-3T exhibited 16S rRNA gene sequence similarities of 97.1-98.1% to type strains of P. dokdonensis, P. haliotis, P. marinaquae, P. insulae, P. vadi, P. glomeratus, P. irgensii and P. reichenbachii, and 94.0-96.9% to those of the other Polaribacter species. DNA-DNA relatedness values of strain DBTF-3T with type strains of P. marinaquae and P. insulae were 14-19%. Average nucleotide identity and digital DNA-DNA hybridization values between strain DBTF-3T and type strains of six other Polaribacter species were 76.5-83.5% and 20.9-27.1%, respectively. Strain DBTF-3T contained MK-6 as the predominant menaquinone, and iso-C15:0, summed feature 3, iso-C15:1 G and iso-C15:0 3-OH as the major fatty acids. The major polar lipids were phosphatidylethanolamine and one unidentified lipid. Differential phenotypic properties, together with its phylogenetic and genetic distinctiveness, revealed that strain DBTF-3T is separated from Polaribacter species. On the basis of the data presented, strain DBTF-3T (= KACC 19612T = NBRC 113191T) represents a novel species of the genus Polaribacter, for which the name Polaribacter aestuariivivens sp. nov. is proposed.

Ulvibacterium marinum gen. nov., sp. nov., a novel marine bacterium of the family Flavobacteriaceae, isolated from a culture of the green alga Ulva prolifera

A Gram-stain negative, aerobic, rod-shaped, and non-motile bacterium, designated strain CCMM003^T, was isolated from a culture of the green alga Ulva prolifera. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CCMM003^T belongs to the family Flavobacteriaceae and exhibits a close relationship to Pseudozobellia thermophila DSM 19858^T (92.5%). Optimal growth occurred in the presence of 4% (w/v) NaCl, at pH 7.0 and 30 °C. The polar lipids of strain CCMM003^T consisted of phosphatidylethanolamine and six unidentified lipids. The predominant isoprenoid quinone was MK-6. The major fatty acids were iso-C_15:0, iso-C_15:1 G, iso-C_17:0 3-OH and summed feature 3 (C_16:1ω7c and/or iso-C_15:0 2-OH). The DNA G + C content of strain CCMM003^T calculated on the basis of the genome sequence was 41.2 mol% and the genome size was 5.9 Mbp. On the basis of data from this polyphasic study, strain CCMM003^T is considered to represent a novel genus and species of the family Flavobacteriaceae, for which the name Ulvibacterium marinum gen. nov., sp. nov. is proposed. The type strain is CCMM003^T (= MCCC 1K03244^T =KCTC 52639^T).

Polaribacter insulae sp. nov., isolated from a tidal flat

A Gram-stain-negative, aerobic, non-motile and ovoid or rod-shaped bacterial strain, designated OITF-22^T, was isolated from a tidal flat of Oido, an island of South Korea, and subjected to a polyphasic taxonomic study. Strain OITF-22^T grew optimally at 25 °C, at pH 7.0-8.0 and in the presence of 2.0-3.0 % (w/v) NaCl. The phylogenetic trees based on 16S rRNA gene sequences showed that strain OITF-22^T fell within the clade comprising the type strains of Polaribacter species. Strain OITF-22^T exhibited 16S rRNA gene sequence similarity values of 97.2-99.4 % to the type strains of Polaribacter vadi, P. haliotis, P. atrinae, P. dokdonensis, P. litorisediminis,P. reichenbachii, P. irgensii and P. marinaquae, and of 93.0-96.9 % to the type strains of the other Polaribacter species. Strain OITF-22^T contained MK-6 as the predominant menaquinone and iso-C15 : 0 and iso-C15 : 0 3-OH as the major fatty acids. The major polar lipids detected in strain OITF-22^T were phosphatidylethanolamine and one unidentified lipid. The DNA G+C content of strain OITF-22^T was 32.3 mol% and its DNA-DNA relatedness values with the type strains of the eight phylogenetically most closely related Polaribacter species were 9-32 %. Differential phenotypic properties, together with phylogenetic and genetic distinctiveness, revealed that strain OITF-22^T is separated from recognized species of the genus Polaribacter. On the basis of the data presented, strain OITF-22^T is considered to represent a novel species of the genus Polaribacter, for which the name Polaribacter insulae sp. nov. is proposed. The type strain is OITF-22^T (=KCTC 52658^T=NBRC 112706^T).

Polaribacter pacificus sp. nov., isolated from a deep-sea polymetallic nodule from the Eastern Pacific Ocean

A Gram-staining-negative, yellow-colony-forming, rod-shaped, non-flagellated and facultatively aerobic strain, designed HRA130-1T, was isolated from a deep-sea polymetallic nodule from the Pacific Clarion-Clipperton Fracture Zone (CCFZ). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain HRA130-1T belonged to the genus Polaribacter (96.3-93.2 % 16S rRNA gene sequence similarity), and exhibited 94 % 16S rRNA gene sequence similarity to Polaribacter filamentus KCTC 23135T (type species) and the highest sequence similarity to Polaribacter huanghezhanensis KCTC 32516T (96.3 %). Optimal growth occurred in the presence of 4 % (w/v) NaCl, at pH 7.0 and 16 °C. The DNA G+C content of strain HRA130-1T was 35.9 mol%. The major fatty acid was iso-C15 : 0. The predominant respiratory quinone was menaquinone-6 (MK-6). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, one unidentified phospholipid and an unidentified aminolipid. On the basis of data from the present taxonomic study using a polyphasic approach, strain HRA130-1T represents a novel species of the genus Polaribacter, for which the name Polaribacter pacificus sp. nov. is proposed. The type strain is HRA130-1T (=KCTC 52370T=MCCC 1K03199T=JCM 31460T=CGMCC 1.15763T).

Polaribacter litorisediminis sp. nov., isolated from a tidal flat

A Gram-stain-negative, aerobic, non-motile and ovoid or rod-shaped bacterial strain, designated OITF-11T, was isolated from a tidal flat in Oido, an island of South Korea, and subjected to a polyphasic taxonomic study. Strain OITF-11T grew optimally at 25 °C, at pH 7.0-8.0 and in the presence of 2.0 % (w/v) NaCl. The phylogenetic trees based on 16S rRNA gene sequences showed that strain OITF-11T belonged to the genus Polaribacter. Strain OITF-11T exhibited 16S rRNA gene sequence similarity values of 97.4-98.1 % to Polaribacter haliotis RA4-7T, Polaribacter atrinae KACC 17473T, Polaribacter dokdonensis DSW-5T and Polaribacter marinaquae KCTC 42664T, and of 94.1-96.9 % to the type strains of the other Polaribacter species. Strain OITF-11T contained menaquinone MK-6 as the predominant menaquinone and iso-C15 : 0, iso-C15 : 1 G, iso-C15 : 0 3-OH, iso-C17 : 0 3-OH and C15 : 1ω6c as the major fatty acids. The major polar lipids detected in strain OITF-11T were phosphatidylethanolamine, phosphatidylmonomethylethanolamine and one unidentified lipid. The DNA G+C content of strain OITF-11T was 32.2 mol% and its DNA-DNA relatedness values with the type strains of P. haliotis, P. atrinae, P. dokdonensis and P. marinaquae were 14-33 %. Differential phenotypic properties, together with its phylogenetic and genetic distinctiveness, revealed that strain OITF-11T is separated from recognized species of the genus Polaribacter. On the basis of the data presented, strain OITF-11T is considered to represent a novel species of the genus Polaribacter, for which the name Polaribacter litorisediminis sp. nov. is proposed. The type strain is OITF-11T (=KCTC 52500T=NBRC 112457T).

Characterization and Biotechnological Potential Analysis of a New Exopolysaccharide from the Arctic Marine Bacterium Polaribacter sp. SM1127

Although many kinds of exopolysaccharides (EPSs) from microorganisms have been used in industry, the exploration and utilization of EPSs from polar microorganisms is still rather rare. In this study, a flavobacterial strain, SM1127, from the Arctic brown alga Laminaria, was screened for its high EPS production (2.11 g/l) and was identified as belonging to the genus Polaribacter. The EPS secreted by strain SM1127 has a molecular mass of 220 kDa, and it mainly comprises N-acetyl glucosamine, mannose and glucuronic acid residues bound by heterogeneous linkages. Rheological studies on the aqueous EPS showed that it had a high viscosity and good shear-thinning property. Moreover, the EPS showed a high tolerance to high salinity and a wide pH range. The EPS also had good antioxidant activity. Particularly, its moisture-retention ability was superior to that of any other reported EPS or functional ingredient generally used in cosmetics. The EPS also showed a protective effect on human dermal fibroblasts at low temperature (4 °C). Safety assessment indicated that the EPS is safe for oral administration and external use. These results indicate the promising potential of the EPS from strain SM1127 in the food, cosmetic, pharmaceutical and biomedical fields.