Degradation of Alginate by a Newly Isolated Marine Bacterium Agarivorans sp. B2Z047.

Alginate is the main component of brown algae, which is an important primary production in marine ecosystems and represents a huge marine biomass. The efficient utilization of alginate depends on alginate lyases to catalyze the degradation, and remains to be further explored. In this study, 354 strains were isolated from the gut of adult abalones, which mainly feed on brown algae. Among them, 100 alginate-degrading strains were gained and the majority belonged to the Gammaproteobacteria, followed by the Bacteroidetes and Alphaproteobacteria. A marine bacterium, Agarivorans sp. B2Z047, had the strongest degradation ability of alginate with the largest degradation circle and the highest enzyme activity. The optimal alginate lyase production medium of strain B2Z047 was determined as 1.1% sodium alginate, 0.3% yeast extract, 1% NaCl, and 0.1% MgSO4 in artificial seawater (pH 7.0). Cells of strain B2Z047 were Gram-stain-negative, aerobic, motile by flagella, short rod-shaped, and approximately 0.7-0.9 µm width and 1.2-1.9 µm length. The optimal growth conditions were determined to be at 30 °C, pH 7.0-8.0, and in 3% (w/v) NaCl. A total of 12 potential alginate lyase genes were identified through whole genome sequencing and prediction, which belonged to polysaccharide lyase family 6, 7, 17, and 38 (PL6, PL7, PL17, and PL38, respectively). Furthermore, the degradation products of nine alginate lyases were detected, among which Aly38A was the first alginate lyase belonging to the PL38 family that has been found to degrade alginate. The combination of alginate lyases functioning in the alginate-degrading process was further demonstrated by the growth curve and alginate lyase production of strain B2Z047 cultivated with or without sodium alginate, as well as the content changes of total sugar and reducing sugar and the transcript levels of alginate lyase genes. A simplified model was proposed to explain the alginate utilization process of Agarivorans sp. B2Z047.

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).

Aquimarina algicola sp. nov., isolated from the surface of a marine red alga.

A bacterial strain, designated M625T, was isolated from the surface of a marine red alga. Phylogenetic trees were reconstructed based on the 16S rRNA gene and RpoB protein sequences, which indicated that the strain belongs to the genus Aquimarina within the family Flavobacteriaceae. Strain M625T showed high sequence similarities to A. aggregata RZW4-3-2 T (95.7%), A. seongsanensis CBA3208T (95.3%) and A. versatilis CBA3207T (95.0%). The AAI and POCP values between strain M625T and A. muelleri DSM 19832 T were 71.8% and 57.9% respectively. The dDDH and ANI values between strain M625T and A. aggregata were 19.5% and 74.6% respectively. The strain was Gram-stain negative, strictly aerobic, non-motile and long rod-shaped, and positive for hydrolysis of starch, cellulose, alginate, DNA and Tween 20. The dominant respiratory quinone was MK-6. The major fatty acids were iso-C15:0, iso-C17:0 3-OH, and iso-C15:1 G, and the polar lipids consisted of phosphatidylethanolamine, one unidentified phospholipid, two unidentified aminolipids, and seven unidentified lipids. Based on the polyphasic comparisons, strain M625T is proposed to represent a novel species within the genus Aquimarina, for which the name Aquimarina algicola sp. nov. (type strain M625T = MCCC 1H00399T = KCTC 72685 T) was proposed.

Ruegeria haliotis sp. nov., Isolated from the Gut of the Abalone Haliotis rubra.

A Gram-stain-negative, aerobic, non-motile, white-pigmented, short rod-shaped, and alginate-degrading bacterium, designated B1Z28T, was isolated from the gut of the abalone Haliotis rubra obtained at Weihai, China. Strain B1Z28T was found to grow at 4-35 °C, pH 6.5-9.0, and in the presence of 0.5-8.0% (w/v) NaCl. Cells were positive for oxidase and catalase activity. The 16S rRNA-based phylogenetic analysis revealed that the nearest phylogenetic neighbors of strain B1Z28T were Tritonibacter scottomollicae MCCC 1A06440T (98.1%), Ruegeria faecimaris KCTC 23044T (98.0%), and Ruegeria meonggei KCTC 32450T (97.8%). Based on phylogenomic analysis, the average nucleotide identity (ANI) values between strain B1Z28T and the neighbor strains were 71.6, 77.2, and 78.1%, respectively; the digital DNA-DNA hybridization (dDDH) values based on the draft genomes between strain B1Z28T and its closest neighbors were 20.5, 20.8, and 21.6%, respectively. Ubiquinone-10 (Q-10) was detected as the predominant respiratory quinone. The dominant cellular fatty acids were Summed feature 8 (contained C18:1 ω7c and/or C18:1 ω6c). The polar lipids included phosphatidylethanolamine (PE), diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phospholipid (PL), aminolipid (AL), and three unidentified lipids. Based on the phylogenetic and phenotypic characteristics, strain B1Z28T is considered to represent a novel species of the genus Ruegeria, for which the name Ruegeria haliotis sp. nov. is proposed. The type strain is B1Z28T (= KCTC 72686T = MCCC 1H00393T).

Tamlana haliotis sp. nov., isolated from the gut of the abalone Haliotis rubra.

A Gram-stain-negative, aerobic, non-motile, yellow-pigmented rod-shaped and alginate-degrading bacterium, designated B1N29T, was isolated from the gut of the abalone Haliotis rubra obtained in Weihai, China. Strain B1N29T was found to grow at 4-35 ℃ (optimum, 25 ℃), at pH 6.5-9.0 (optimum, 7.0-7.5) and in the presence of 0.5-9% (w/v) NaCl (optimum, 2%). Cells were positive for oxidase and catalase activity. The 16S rRNA-based phylogenetic analysis revealed that the nearest phylogenetic neighbors of strain B1N29T were Tamlana carrageenivorans KCTC 62451T (98.2%) and Tamlana agarivorans KCTC 22176T (97.7%). Based on the phylogenomic analysis, the average nucleotide identity (ANI) values between strain B1N29T and the neighbor strains were 79.2 and 79.0%, respectively; the digital DNA-DNA hybridization (dDDH) values between strain B1N29T and its two closest neighbors were 22.8 and 23.0%, respectively. Menaquinone-6 (MK-6) was detected as the sole respiratory quinone. The dominant cellular fatty acids were iso-C15:0, iso-C17:0 3-OH, anteiso-C15:0 and iso-C15:1 G. The polar lipids included phosphatidylethanolamine, one aminophospholipid, seven aminolipids and five unidentified lipids. Based on the phylogenetic and phenotypic characteristics, strain B1N29T is considered to represent a novel species of the genus Tamlana, for which the name Tamlana haliotis sp. nov. is proposed. The type strain is B1N29T (= KCTC 72683T = MCCC 1H00394T).

Marinicella rhabdoformis sp. nov., isolated from coastal sediment.

A Gram-stain-negative, rod-shaped, facultative anaerobic bacterium, designated strain 3539T, was isolated from coastal sediment of Weihai, PR China. Optimal growth occurred at 28 °C, pH 7.5-8.0 and in the presence of 3.0 % (w/v) NaCl. Results of phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 3539T formed a robust clade with members of the genus Marinicella and was closely related to Marinicella litoralis JCM 16154T, Marinicella sediminis F2T and Marinicella pacifica sw153T with 97.7, 96.2 and 95.4 % sequence similarity, respectively. The average amino acid identity, percentage of conserved proteins, average nucleotide identity and digital DNA-DNA hybridization values between strain 3539T and M. litoralis JCM 16154T were 64.9, 68.3, 72.8 and 18.9 %, respectively. The genomic DNA G+C content of strain 3539T was 42.0 mol%. The dominant respiratory quinone was ubiquinone-8, and the major fatty acids were iso-C15 : 0 and summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c). The polar lipids of strain 3539T consisted of phosphatidyldimethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, one unidentified aminophospholipid, one unidentified lipid and three unidentified phospholipids. Based on the combination of phylogenetic, phenotypic and chemotaxonomic data, strain 3539T is considered to represent a novel species within the genus Marinicella in he family Alcanivoracaceae, for which the name Marinicella rhabdoformis sp. nov. is proposed. The type strain of the new species is 3539T (=KCTC 72414T=MCCC 1H00388T).

Hyunsoonleella flava sp. nov., isolated from marine sediment.

A novel Gram-stain-negative, strictly aerobic, rod-shaped, non-motile and yellow-pigmented bacterial strain, designated T58T, was isolated from a marine sediment sample collected from the coastal area of Weihai, PR China. Strain T58T was most closely related to Hyunsoonleella pacifica SW033T with 97.1 % 16S rRNA gene sequence similarity, followed by Hyunsoonleella jejuensis KCTC 22242T (96.9 %). Based on 16S rRNA gene sequences, the phylogenetic analysis indicated that strain T58T represented a member of the genus Hyunsoonleella within the family Flavobacteriaceae of the phylum Bacteroidetes. Strain T58T was found to grow optimally at 30 °C, at pH 7.0-7.5 and in the presence of 2.0-3.0 % (w/v) NaCl. The major fatty acids were iso-C15  :  0, iso-C15 : 1 G, iso-C17 : 0 3-OH and iso-C15 : 0 3-OH. The major isoprenoid quinone was menaquinone 6 (MK-6). The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids and two unidentified lipids. The DNA G+C content of the genomic DNA was 35.0 mol%. On the basis of its phylogenetic, phenotypic and chemotaxonomic characteristics, strain T58T is considered to represent a novel species of the genus Hyunsoonleella, for which the name Hyunsoonleella flava sp. nov. is proposed. The type strain is T58T (=KCTC 72081T=MCCC 1H00359T).

Formosa maritima sp. nov., isolated from coastal sediment.

A Gram-stain-negative, strictly aerobic, gliding-motile, rod-shaped and orange-pigmented bacterium, designated 1494T, was isolated from marine sediment collected off the coast of Weihai, PR China. Strain 1494T was found to grow at 4-37 °C (optimum, 30 °C), at pH 6.0-9.0 (pH 7.0) and in the presence of 0-8 % (w/v) NaCl (2 %). Cells were positive for oxidase and catalase activity. The results of 16S rRNA gene based phylogenetic analysis revealed that strain 1494T belonged to the genus Formosa and exhibited the highest sequence similarity to Formosa spongicola KCTC 22662 T (98.4 %). Menaquinone-6 (MK-6) was detected as the major respiratory quinone. The dominant cellular fatty acids were iso-C15 : 1 G and iso-C15 : 0. The DNA G+C content of strain 1494T was 31.1 mol%. The major polar lipids included phosphatidylethanolamine, one unidentified phospholipid and one unidentified lipid. Based on its phylogenetic and phenotypic characteristics, strain 1494T is considered to represent a novel species from the genus Formosa, for which the name Formosa maritima sp. nov. is proposed. The type strain is 1494T (=KCTC 72531T=MCCC 1H00385T).

Seonamhaeicola maritimus sp. nov., isolated from coastal sediment.

A Gram-stain-negative, facultatively anaerobic, non-motile, rod-shaped and orange-pigmented bacterium, designated 1505T, was isolated from marine sediment that was obtained off the coast of Weihai, PR China. Strain 1505T was found to grow at 10-35 °C (optimum, 28 °C), at pH 6.0-9.0 (optimum, 7.5) and in the presence of 1-4 % (w/v) NaCl (optimum, 2 %). Cells were positive for oxidase and catalase activity. The 16S rRNA gene based phylogenetic analysis revealed that the nearest phylogenetic neighbours of strain 1505T were Seonamhaeicola algicola Gy8T (97.1 %), Seonamhaeicola marinus B011T (96.3 %) and Seonamhaeicola aphaedonensis KCTC 32578T (95.6 %). Based on phylogenomic analysis, the average nucleotide identity values between strain 1505T and S. algicola Gy8T, S. marinus B011T and S. aphaedonensis KCTC 32578T were 75.9, 76.0 and 77.7 %, respectively; the digital DNA-DNA hybridization values based on the draft genomes between strain 1505T and S. algicola Gy8T, S. marinus B011T and S. aphaedonensis KCTC 32578T were 20.0, 20.7 and 21.4 %, respectively. Menaquinone-6 (MK-6) was detected as the major respiratory quinone. The dominant cellular fatty acids were iso-C15 : 1 G and C18 : 1ω9c. The DNA G+C content of strain 1505T was 33.3 mol%. The polar lipids included phosphatidylethanolamine, six aminolipids and four unidentified lipids. Based on its phylogenetic and phenotypic characteristics, strain 1505T is considered to represent a novel species of the genus Seonamhaeicola, for which the name Seonamhaeicola maritimus sp. nov. is proposed. The type strain is 1505T (=KCTC 72528T=MCCC 1H00389T).

Flavobacterium cerinum sp. nov., isolated from Arctic tundra soil.

In the present paper, we describe a new species of the genus Flavobacterium, designated as strain 1E403T, which was isolated from a soil sample collected from the Arctic. Strain 1E403T was Gram-stain-negative, yellow-pigmented, rod-shaped, gliding and aerobic. Growth occurred at 4-37 °C (optimum, 28 °C), pH 6.0-9.0 (pH 7.0) and with 0-2 % (w/v) NaCl (0 %) on modified marine agar 2216. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that strain 1E403T was affiliated with the genus Flavobacterium and was more closely related to Flavobacterium subsaxonicum DSM 21790T (96.6 %) than to other species. In silico genomic comparisons, including average nucleotide identity and the digital DNA-DNA hybridization values, showed 73.9 % and 18.8 % identity to the closest relative Flavobacterium subsaxonicum DSM 21790T, respectively. The average amino acid identity value between strain 1E403T and Flavobacterium aquatile DSM 1132T was 63.8 %. The DNA G+C content of the strain was 36.8 %, while the sole respiratory quinone was menaquinone-6. Iso-C15 : 0 and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) were the major fatty acids (>10 %) of strain 1E403T. The polar lipid profile of strain 1E403T contained phosphatidylethanolamine, four unidentified aminolipids and two unidentified phospholipids. Based on the phenotypic characteristics, chemotaxonomic characteristics and phylogenetic inference, strain 1E403T represents a novel species of the genus Flavobacterium, and we propose the name Flavobacterium cerinum sp. nov. The type strain of Flavobacterium cerinum sp. nov. is 1E403T (=KCTC 62960T=MCCC 1H00356T).