Xiao-n Yu

Isolation and Complete Genome Sequence of Algibacter alginolytica sp. nov., a Novel Seaweed-Degrading Bacteroidetes Bacterium with Diverse Putative Polysaccharide Utilization Loci

ABSTRACT The members of the phylum Bacteroidetes are recognized as some of the most important specialists for the degradation of polysaccharides. However, in contrast to research on Bacteroidetes in the human gut, research on polysaccharide degradation by marine Bacteroidetes is still rare. The genus Algibacter belongs to the Flavobacteriaceae family of the Bacteroidetes, and most species in this genus are isolated from or near the habitat of algae, indicating a preference for the complex polysaccharides of algae. In this work, a novel brown-seaweed-degrading strain designated HZ22 was isolated from the surface of a brown seaweed (Laminaria japonica). On the basis of its physiological, chemotaxonomic, and genotypic characteristics, it is proposed that strain HZ22 represents a novel species in the genus Algibacter with the proposed name Algibacter alginolytica sp. nov. The genome of strain HZ22, the type strain of this species, harbors 3,371 coding sequences (CDSs) and 255 carbohydrate-active enzymes (CAZymes), including 104 glycoside hydrolases (GHs) and 18 polysaccharide lyases (PLs); this appears to be the highest proportion of CAZymes (∼7.5%) among the reported strains in the class Flavobacteria. Seventeen polysaccharide utilization loci (PUL) are predicted to be specific for marine polysaccharides, especially algal polysaccharides from red, green, and brown seaweeds. In particular, PUL N is predicted to be specific for alginate. Taking these findings together with the results of assays of crude alginate lyases, we prove that strain HZ22T can completely degrade alginate. This work reveals that strain HZ22T has good potential for the degradation of algal polysaccharides and that the structure and related mechanism of PUL in strain HZ22T are worth further research.

Hyphobacterium vulgare gen. nov., sp. nov., a novel alpha-proteobacterium isolated from seawater in the South China Sea.

A Gram-stain-negative, aerobic, non-spore-forming, non-motile, oval to rod-shaped, prosthecate bacterium, designated strain WM6T, was isolated from a seawater sample collected from the South China Sea at a depth of 150 m and subjected to a polyphasic taxonomic investigation. Cells of strain WM6T were approximately 0.5-0.6 µm in width and 0.8-1.2 µm in length, and colonies were smooth, circular, convex and whitish yellow. Strain WM6T was found to grow at 10-45 °C (optimum, 30 °C), at pH 6.5-9.0 (optimum, pH 7.5-8.5) and with 1-6 % (w/v) NaCl (optimum, 1-2 %). Chemotaxonomic analysis showed the predominant respiratory quinone and the major fatty acid of strains WM6T were ubiquinone-10 and C18 : 1ω7c, respectively. The polar lipids of strain WM6T were phosphatidylglycerol, glucuronopyranosyldiglyceride, monoglycosyldiglyceride, sulfo-quinovosyl diacylglycerol, seven unknown glycolipids and two unknown lipids. The DNA G+C content of strain WM6T was determined to be 59.8 mol% by HPLC. 16S rRNA gene sequence similarities showed that strain WM6T was related most closely to the genus Maricaulis with a similarity range from 92.3 to 93.8 %. Phylogenetic trees reconstructed with the neighbour-joining and maximum-likelihood methods using mega and maximum-likelihood methods using arb showed that strain WM6T constituted a separated branch in the family Hyphomonadaceae. Differential phenotypic properties, together with phylogenetic distinctiveness, demonstrated that strain WM6T is clearly distinct from any validly published genus. On the basis of these features, strain WM6T represents a novel species of a new genus with the name Hyphobacterium vulgare gen. nov., sp. nov. The type strain of Hyphobacterium vulgare is WM6T (=MCCC 1K03222T=KCTC 52487T).

Mesorhizobium oceanicum sp. nov., isolated from deep seawater

A novel Gram-staining-negative, oval-shaped (0.4-0.6×0.8-1.0 µm), non-motile strain without flagella, designated B7T, was isolated from deep seawater in the South China Sea. Strain B7T was able to grow at 25-40 °C (optimum 35 °C), at pH 5.5-9.0 (optimum pH 7.0) and with 0-8 % (w/v) NaCl (optimum 3 %). Chemotaxonomic analysis showed that the predominant isoprenoid quinone was Q-10 and the dominant fatty acids were C19 : 0 cyclo 8c and summed feature 8 (C18 : 1ω7c/C18 : 1ω6c). The polar lipids of strain B7T were diphosphatidyglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, one unknown aminophospholipid, one unknown glycolipid and three unknown lipids. The DNA G+C content of the genomic DNA was 65.1 mol%. Phylogenetic analysis of 16S rRNA gene sequences showed that strain B7T belongs to the genus Mesorhizobium with similarities ranging from 96.2 to 97.5 %. Phylogenetic analyses of housekeeping genes recA, atpD and glnII indicated that strain B7T represented a distinct evolutionary lineage with the genus Mesorhizobium. OrthoANI values between strain B7T and related strains of the genus Mesorhizobium (<80 %) were lower than the threshold value of 95 % ANI relatedness for species demarcation. Therefore, strain B7T is concluded to represent a novel species of the genus Mesorhizobium, for which the name Mesorhizobium oceanicumsp. nov. is proposed. The type strain is B7T (=KCTC 42783T=MCCC 1K02305T).

Marinibaculum pumilum gen. nov., sp. nov., isolated from seawater

A Gram-stain-negative, facultatively anaerobic, motile and rod-shaped strain, designed H2T, was isolated from the Western Pacific Ocean, and subjected to a taxonomic investigation using a polyphasic approach. Strain H2T grew at 15-40 °C and pH 6.0-9.0 (optimum 37 °C and pH 6.5), and with 1-10 % (w/v) NaCl (optimum 2 %). The predominant respiratory quinone was ubiquinone-10 (Q-10) and the major fatty acids identified were C19 : 0 cyclo ω8c, C18 : 1ω7c, C18 : 0 and 11-methyl-C18 : 1ω7c. The polar lipids of strain H2T consisted of phosphatidylglycerol, one unknown phospholipid, one unknown glycolipid and three unidentified aminolipids. The DNA G+C content was 75.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain H2T formed a distinct clade belong to the family Rhodospirillaceae within the Alphaproteobacteria. On the basis of morphological, physiological and chemotaxonomic characteristics, together with the results of phylogenetic analysis, strain H2T represents a novel species in a new genus in the family Rhodospirillaceae, for which the name Marinibaculumpumilum gen. nov., sp. nov. is proposed. The type strain of the type species is H2T(=MCCC 1K02279T=KCTC 42964T).

Marinicaulis flavus gen. nov., sp. nov., a novel stalked bacterium of the family Parvularculaceae

A Gram-stain-negative, aerobic, ovoid or short rod-shaped bacterium with prosthecates and flagella, designated SY-3-19T, was isolated from the surface seawater of the South China Sea, and subjected to a polyphasic taxonomic study. The isolate grew at 4-40 °C and pH 5.0-9.0 (optimum 28 °C and pH 6.5-7.5), and with 0.5-16.0 % (w/v) NaCl (optimum 4 %). It was positive for oxidase and catalase activity. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SY-3-19T constituted a separate branch in the family Parvularculaceae, sharing the highest sequence similarities to the genera Aquisalinus (91.9 %), Amphiplicatus (91.1 %) and Parvularcula(91.0-89.4 %). The sole respiratory quinone was ubiquinone-10 and the principal fatty acids (>10 %) were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), 11 methyl C18 : 1ω7c and C16 : 0. The polar lipids of strain SY-3-19T consisted of phosphatidylglycerol, nine unidentified glycolipids and four unidentified lipids. The DNA G+C content was 60.9 mol%. On the basis of morphological, physiological and chemotaxonomic characteristics, together with the results of phylogenetic analysis, strain SY-3-19T is described as a novel species in a novel genus, for which the name Marinicaulis flavus gen. nov., sp. nov. (type strain SY-3-19T=MCCC 1K03432T=KCTC 62156T) is proposed.

Luteolibacter flavescens sp. nov., isolated from deep seawater

A novel Gram-stain-negative, rod-shaped, non-motile strain, designated GKXT, was isolated from deep seawater. Strain GKXT was able to grow at 20-35 °C (optimum, 25 °C), pH 5.5-9.5 (optimum, 7.5) and 0-4.0 % (w/v) NaCl (optimum, 1.0 %). The major fatty acids were C16 : 1ω9c (15.4 %), C16 : 0 (18.4 %), C14 : 0 (12.0 %), iso-C14 : 0 (30.1 %) and anteiso-C15 : 0 (5.7 %). Strain GKXT contained phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and an unidentified glycolipid as the main polar lipids. The only isoprenoid quinone was menaquinone-9. The diagnostic amino acids of the cell-wall peptidoglycan contained meso-diaminopimelic acid. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain GKXT belonged to the genus Luteolibacter in the family Verrucomicrobiaceae. The 16S rRNA gene sequence of this strain showed 98.0, 93.5 and 93.3 % sequence similarity, respectively, with those of Luteolibacter arcticus MC 3726T, L.uteolibacter pohnpeiensisA4T-83T and L.uteolibacter cuticulihirudinis E100T. DNA-DNA hybridization value of strain GKXT with L. arcticus MC 3726T was 33.1 %. The G+C content of the genomic DNA was 59.5 mol%. On the basis of the genotypic, phenotypic, phylogenetic and chemotaxonomic characteristics, strain GKXT was proposed to represent a novel species of the genus Luteolibacter, named Luteolibacter flavescens sp. nov. (type strain GKXT=MCCC 1K03193T=KCTC 52361T).

Marinobacterium zhoushanense sp. nov., isolated from surface seawater.

A Gram-stain-negative, facultatively anaerobic bacterium, designated WM3T, was isolated from surface seawater collected from the East China Sea. Cells were catalase- and oxidase-positive, short rods and motile by means of a single polar flagellum. Growth occurred at 15-43 °C (optimum 37-40 C), pH 5.5-9.5 (optimum pH 6.5-7.5) and with 0.25-9.0 % (w/v) NaCl (optimum 1.0-1.5 %). Chemotaxonomic analysis showed that the respiratory quinone was ubiquinone-8, the major fatty acids included C16 : 0 (23.6 %), C18 : 1ω7c (26.2 %) and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH, 22.1 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain WM3T was most closely related to the genus Marinobacterium, sharing the highest 16S rRNA gene sequence similarity of 95.5 % with both Marinobacterium litorale KCTC 12756T and Marinobacterium mangrovicola DSM 27697T. The genomic DNA G+C content of the strain WM3T was 55.8 mol%. On the basis of phenotypic, chemotaxonomic and genotypic characteristics presented in this study, strain WM3T is suggested to represent a novel species of the genus Marinobacterium, for which the name Marinobacterium zhoushanense sp. nov. is proposed. The type strain is WM3T (=KCTC 42782T=CGMCC 1.15341T).

Minwuia thermotolerans gen. nov., sp. nov., a marine bacterium forming a deep branch in the Alphaproteobacteria, and proposal of Minwuiaceae fam. nov. and Minwuiales ord. nov.

Two Gram-stain-negative, strictly aerobic, non-motile, non-spore-forming, rod-shaped bacteria, designated as SY3-15Tand SY3-13, were isolated from a seawater sample of the South China Sea. Colonies were 0.5-1.0 mm in diameter, smooth, circular, convex and translucent after growth on marine agar at 37 °C for 3 days. The strains were found to grow at 20-50 °C (optimum, 42 °C), pH 6.0-8.5 (optimum, pH 6.5-7.5) and with 0.5-6.0 % (w/v) NaCl (optimum, 1.5-2.0 %). Chemotaxonomic analysis showed the sole respiratory quinone to be ubiquinone-10, the major fatty acids (>10 %) were C16 : 0 3-OH, C19 : 0cyclo ω9c, C18 : 1 3-OH and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), and the polar lipids were phosphatidylglycerol, two unidentified aminolipids and three unidentified lipids. The DNA G+C content was 67.2-67.4 mol% calculated by genome. The 16S rRNA gene sequences of strains SY3-15T and SY3-13 were identical and related to the genus Lutibaculum with a similarity of 92.1 %. The 16S rRNA gene phylogenetic trees reconstructed with neighbour-joining, maximum-parsimony and minimum-evolution methods showed that the strains constituted a deep and separated branch from other families of Alphaproteobacteria, and the phylogenetic trees based on concatenated 163 protein sequences from genome sequences showed that the clade in which strains SY3-15T and SY3-13 located was separated from the clade of the other orders of Alphaproteobacteria, indicating it may represent a novel family of a novel order. Based on their phenotypic properties and their phylogenetic distinctiveness, we propose strains SY3-15T (=MCCC 1K03467T=KCTC 62335T) and SY3-13 (=MCCC 1K03466=KCTC 62329) to represent a novel species of a novel genus with the name Minwuia thermotolerans gen. nov., sp. nov., and we propose Minwuiaceae fam. nov. and Minwuiales ord. nov. with Minwuia as the type genus.

Rhodohalobacter barkolensis sp. nov., isolated from a saline lake and emended description of the genus Rhodohalobacter

A Gram-stain-negative, non-motile, aerobic, rod-shaped bacterium, designated 15182T, was isolated from a saline lake in China. The novel strain 15182T was able to grow at 10-40 °C (optimum, 37 °C), pH 7.0-8.0 (optimum, 7.5) and with 0.5-4 % NaCl (optimum, 2-3 %, w/v). The phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 15182T was most closely related to the genus Rhodohalobacter by sharing the highest sequence similarity of 97.0 % with Rhodohalobacter halophilus JZ3C29T. Chemotaxonomic analysis showed that the sole respiratory quinone was menaquinone 7, the major fatty acids included C16 : 0 N alcohol and C16 : 1ω11c. The major polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, four uncharacterized glycolipids, one uncharacterized phospholipid and two uncharacterized lipids. The genomic DNA G+C content of the strain 15182T was 42.4 mol%. The average nucleotide identity value between 15182T and R. halophilus JZ3C29T was 75.4 %, and the in silico DNA-DNA hybridization value of the two strains was 19.1 %. On the basis of its phenotypic, chemotaxonomic, genotypic and genomic characteristics presented in this study, strain 15182T is suggested to represent a novel species in the genus Rhodohalobacter, for which the name Rhodohalobacter barkolensis sp. nov. is proposed. The type strain is 15182T (=KCTC 62172T=MCCC 1K03442T). An emended description of the genus Rhodohalobacter is also presented.

Roseovarius nitratireducens sp. nov., a halotolerant bacterium isolated from a saline lake

A Gram-stain-negative, aerobic, non-motile and ovoid- to rod-shaped bacterial strain, designated TFZT, was isolated from a water sample of a saline lake in Xinjiang, China and subjected to polyphasic taxonomic investigation. Strain TFZT grew at 4-42 °C and pH 6.5-10.0 (optimum, 30 °C and pH 7.0) and with 0.5-18.0 % (w/v) NaCl (optimum, 1.5 %). According to phylogenetic analysis based on 16S rRNA gene sequences, strain TFZT was assigned to the genus Roseovarius with highest 16S rRNA gene sequence similarity of 97.5 % to Roseovarius tolerans EL-172T, followed by Roseovarius azorensis SSW084T (96.6 %) and Roseovarius mucosus DSM 17069T (95.5 %). Digital DNA-DNA hybridization (DDH) and average nucleotide identity (ANI) were determined to evaluate the genomic relationship between strain TFZT and R. tolerans EL-172T. Digital DDH estimation (22.80±2.35 %) as well as ANI (80.1 %) proved the dissimilarity of strain TFZT. Chemotaxonomic analysis showed that strain TFZT contained ubiquinone-10 as the predominant respiratory quinone and possessed summed feature 8 (comprising C18 : 1ω7c and/or ω6c) and C16 : 0 as the predominant form of fatty acid. The polar lipids of strain TFZT consisted of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and five unidentified lipids. The DNA G+C content was 65.4 mol% (by genome sequencing). Based on the polyphasic taxonomic characterization, strain TFZT is considered to represent a novel species of the genus Roseovarius, for which the name Roseovariusnitratireducens sp. nov. is proposed (type strain TFZT=MCCC 1K03339T=KCTC 52967T).