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.

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).

Hymenobacter sediminis sp. nov., isolated from lake sediment.

A Gram-stain-negative, facultatively aerobic, rod-shaped, motile by gliding and pink-pigmented bacterial strain, designated ELS1360T, was isolated from a lake sediment sample collected in Inner Mongolia, PR China. Strain ELS1360T grew optimally at 33 °C, at pH 6.5-7.0 and without NaCl. Strain ELS1360T exhibited 97.3, 97.1 and 96.9 % 16S rRNA gene sequence similarities to Hymenobacter aquatilis HMF3095T, Hymenobacter luteus JCM 30328T and Hymenobacter latericoloratus JCM 30327T, respectively, and 90.4-96.9 % to other members of the genus Hymenobacter. Results of phylogenetic analysis based on 16S rRNA gene sequences showed that strain ELS1360T belonged to the genus Hymenobacter and clustered with H. luteus JCM 30328T and H. latericoloratus JCM 30327T. The predominant cellular fatty acids were iso-C15:0, summed feature 3 and C16:1ω5c. Strain ELS1360T contained MK-7 as the sole menaquinone. The major polar lipids contained phosphatidylethanolamine and two unidentified lipids. The genomic DNA G+C content of strain ELS1360T was 57.1 mol%. Based on the results of our phylogenetic, phenotypic, genotypic and chemotaxonomic analyses, it is concluded that strain ELS1360T represents a novel species within the genus Hymenobacter, for which the name Hymenobacter sediminis sp. nov. is proposed. The type strain is ELS1360T (=KCTC 62449T=MCCC 1H00319T).

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).

Marinicauda salina sp. nov., isolated from a marine solar saltern.

A novel Gram-stain-negative, aerobic, oxidase-positive, motile, dimorphic rod bacterium, with a polar flagellum or a polar prostheca, designated as strain WD6-1T, was isolated from a sediment sample collected from a marine solar saltern located in Weihai, PR China. Growth of strain WD6-1T was observed at 15-45 °C (optimum, 37-40 °C). The pH range for growth was pH 6.0-9.5 (optimum, pH 7.0-7.5) while the NaCl concentration was 1.0-16.0 % (w/v; optimum, 5.0 %). The most closely related species was Marinicauda algicola (97.0 % 16S rRNA gene sequence similarity). The DNA G+C content of strain WD6-1T was 69.5 mol% and the sole respiratory quinone was ubiquinone 10 (Q-10). The major cellular fatty acids (>10 %) of strain WD6-1T included summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1ω6c), C18 : 0 and C17 : 0, and the major polar lipids were glucuronopyranosyldiglyceride, monoglycosyldiglyceride and sulfo-quinovosyl diacylglycerol. Based on the results of phylogenetic, genotypic and phenotypic analyses, the isolate is representative of a new member of the genus Marinicauda, for which the name Marinicaudasalina sp. nov. is proposed. The type strain is WD6-1T (=KCTC 62348T=MCCC 1H00282T).

Paracnuella aquatica gen. nov., sp. nov., a member of the family Chitinophagaceae isolated from a hot spring.

A Gram-stain-negative, rod-shaped bacterium (designated strain N24T) with gliding motility was isolated from thermal spring water sampled at Xi'an, PR China. Cells were 0.4-0.8 µm wide and 1.8-7.8 µm long. Optimal growth occurred at 33 °C and pH 7.0 on Reasoner's 2A (R2A) agar. Strain N24T could produce exopolysaccharide on R2A agar at 33 °C. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain N24T formed a distinct phyletic lineage within the family Chitinophagaceae and was most closely related to members of the genera Flavisolibacter, Cnuella, Niveitalea, Flavitalea, Flaviaesturariibacter and Niastella with 91.7-93.9 % 16S rRNA gene sequence similarities. The major fatty acids of strain N24T were iso-C15 : 0 (31.8 %), iso-C17 : 0 3-OH (16.1 %) and iso-C15 : 1 G (12.9 %). The polar lipid profile consisted of phosphatidylethanolamine, two aminolipids and six unknown lipids; the quinone system consisted of menaquinone-7 (MK-7). The genomic G+C content was 49.3 mol%. On the basis of the evidence presented in this study, strain N24T represents a novel species of a new genus in the family Chitinophagaceae, for which the name Paracnuella aquatica gen. nov., sp. nov. is proposed. The type species is N24T (=KCTC 62083T=MCCC 1H00301T).

Pelagibacterium lacus sp. nov., isolated from lake water.

A Gram-stain-negative, strictly aerobic, oxidase- and catalase-positive, non-gliding, motile with a single polar flagellum, and short rod-shaped bacterial strain, designated XYN52T, was isolated from a freshwater lake in the west of China. Phylogenetic analysis of the 16S rRNA gene determined that strain XYN52T was a member of the genus Pelagibacterium within the family Hyphomicrobiaceae. Strain XYN52T was able to grow at 4-37 °C (optimum, 30 °C), pH 6.0-9.0 (pH 7.5) and in the presence of up to 7.0 % w/v NaCl (0.5 %).The major quinone was ubiquinone 10. The major cellular fatty acids were C18 : 1ω6c/C18 : 1ω7c, C19 : 0ω8c cyclo and 11-methyl C18 : 1ω7c. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and three kinds of glycolipids. The genomic DNA G+C content was 64.5 mol%. On the basis of these data, strain XYN52T represents a novel species in the genus Pelagibacterium, for which the name Pelagibacterium lacus sp. nov. is proposed. The type strain is XYN52T (=KCTC 62845T=MCCC 1H00348T).