Direct Degradation of Fresh and Dried Macroalgae by Agarivorans albus B2Z047.

Marine macroalgae are increasingly recognized for their significant biological and economic potential. The key to unlocking this potential lies in the efficient degradation of all carbohydrates from the macroalgae biomass. However, a variety of polysaccharides (alginate, cellulose, fucoidan, and laminarin), are difficult to degrade simultaneously in a short time. In this study, the brown alga Saccharina japonica was found to be rapidly and thoroughly degraded by the marine bacterium Agarivorans albus B2Z047. This strain harbors a broad spectrum of carbohydrate-active enzymes capable of degrading various polysaccharides, making it uniquely equipped to efficiently break down both fresh and dried kelp, achieving a hydrolysis rate of up to 52%. A transcriptomic analysis elucidated the presence of pivotal enzyme genes implicated in the degradation pathways of alginate, cellulose, fucoidan, and laminarin. This discovery highlights the bacterium's capability for the efficient and comprehensive conversion of kelp biomass, indicating its significant potential in biotechnological applications for macroalgae resource utilization.

Simultaneous determination of serum tryptophan metabolites in an older Chinese population.

Tryptophan (TRP) and its metabolites exhibit significant biological effects and are strongly associated with age-related disease and mortality. However, reports on quantitatively analyzing these metabolites in older individuals are not available. We used ultra-high-performance liquid chromatography-tandem mass spectrometry to optimize and validate a method for isotope dilution analysis of TRP metabolites in older individuals. The targeted analytes are TRP, serotonin or 5-hydroxytryptamine, kynurenine, kynurenic acid, xanthurenic acid, indole-3-acetic acid, indole-3-propionic acid, and tryptamine. The serum sample was purified using solid-phase extraction and was separated on a Waters HSS T3 column (100 mm × 2.1 mm, 1.8 µm). The analytes were detected in the multiple reaction monitoring mode under positive ionization. TRP was confirmed and measured after being diluted 100 times. This method exhibited satisfactory linearity (r > 0.99). The intrabatch and interbatch accuracies (85.7-114%) and precisions (<15%) were acceptable. The standard-normalized matrix effects ranged from 51.6 to 145%. This method was successfully applied to a cohort of 1021 older Chinese individuals, and this study may enable further understanding of the metabolic phenotypes associated with TRP in other populations.

Microvenator marinus gen. nov., sp. nov., isolated from marine sediment, and description of Microvenatoraceae fam. nov. and Lujinxingiaceae fam. nov.

A Gram-stain-negative, facultatively anaerobic, oxidase-negative and catalase-positive predatory bacillus, designated strain V1718T, was isolated from Xiaoshi Island, PR China. Strain V1718T was found to be closely related to Lujinxingia sediminis SEH01T, with 89.8 % similarity in the 16S rRNA gene sequence, followed by Bradymonas sediminis FA350T with a similarity of 88.4 %. Strain V1718T had the ability to prey on other bacteria, and selective predation on members of Algoriphagus, Nocardioides and Bacillus occurred with the strain. Growth was observed within the range of 20-45 °C (optimal at 37 °C), pH 6.5-9.0 (optimal at pH 8.0) and 1-10 % NaCl (optimal at 3-4 %, w/v). The predominant cellular fatty acids in strain V1718T were iso-C15 : 0 (53.0 %) and C16 : 0 (19.1 %). The major polar lipids present in the strain were phosphatidylglycerol and phosphatidylethanolamine, and the respiratory quinone was menaquinone MK-7. The complete genome sequence of strain V1718T was 5 847 748 bp with a G+C content of 55.2 mol%. The topology of the phylogenomic tree indicated that strain V1718T forms a separate branch in the same clade with the genus Lujinxingia and the family Bradymonadaceae. The average nucleotide identity and average amino acid identity values were 66.4 and 48.6 %, respectively, with Bradymonas sediminis FA350T (type species of Bradymonas) and 66.8 % and 48.9 % with Lujinxingia litoralis B210T (type species of Lujinxingia). The genes related to biosynthesis pathways of several important chemical compounds could not be found in the genome of strain V1718T, which was predicted to be the intrinsic reason for predation in this group. The physiological, biochemical and phylogenetic properties of strain V1718T suggest that it belongs to a novel family distinct from other culturable bradymonabacteria. The name Microvenator marinus gen. nov., sp. nov. is proposed, with strain V1718T (=KCTC 72082T=MCCC 1H00380T) as type strain; the name Microvenatoraceae fam. nov. is also proposed. Meanwhile, the genus Lujinxingia can also be taxonomic classified as Lujinxingiaceae fam. nov. Thus, two novel families and a novel genus of the order Bradymonadales are proposed in this paper.

Psychrobacter halodurans sp. nov. and Psychrobacter coccoides sp. nov., two new slightly halophilic bacteria isolated from marine sediment.

In this study, two bacterial strains designated F2608T and F1192T, isolated from marine sediment sampled in Weihai, PR China, were characterized using a polyphasic approach. Strains were aerobic, Gram-stain-negative and motile. According to the results of phylogenetic analyses based on their 16S rRNA genes, these two strains should be classified under the genus Psychrobacter and they both show <98.5% sequence similarity to their closest relative, Psychrobacter celer JCM 12601T. Moreover, strain F2608T showed 97.5% sequence similarity to strain F1192T. Strain F2608T grew at 4-37 °C (optimum, 30-33 °C) and at pH 6.0-9.0 (optimum, pH 6.5-7.0) in the presence of 0-12% (w/v) NaCl (optimum, 4.0-5.0%). Strain F1192T grew at 4-37 °C (optimum, 30 °C) and at pH 5.5-9.0 (optimum, pH 7.0-7.5) in the presence of 0.5-12% (w/v) NaCl (optimum, 3.0-4.0%). The genomic DNA G+C contents of strain F2608T and strain F1192T were 47.4 and 44.9 %, respectively. Genomic characteristics including average nucleotide identity and digital DNA-DNA hybridization values clearly separated strain F2608T from strain F1192T. The sole isoprenoid quinone in these two strains was ubiquinone 8 and the major cellular fatty acids (>10.0%) were C18:1 ω9c and C17:1 ω8c. The major polar lipids of these two strains were phosphatidylglycerol, phosphatidylethanolamine and diphosphatidylglycerol. Based on the results of polyphasic analysis, the two strains represent two novel species of the genus Psychrobacter, for which the names Psychrobacter halodurans sp. nov. and Psychrobacter coccoides sp. nov. are proposed. The type strains are F2608T (=MCCC 1K05774T=KCTC 82766T) and F1192T (=MCCC 1K05775T=KCTC 82765T), respectively.

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.

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.

Tenacibaculum pelagium sp. nov., isolated from marine sediment.

A novel bright yellow pigmented, Gram-stain-negative, gliding, aerobic and rod-shaped marine bacterium, designated strain S7007T, was isolated from a marine sediment sample taken from Jingzi Wharf, Weihai, China. The bacterium was able to grow at 4-33 °C (optimum 28 °C), at pH 6.5-9.0 (optimum 7.0) and with 2.0-4.0% (w/v) NaCl (optimum 3.0%). According to the phylogenetic analysis based on the 16S rRNA gene sequences, strain S7007T was associated with the genus Tenacibaculum and showed highest similarity to Tenacibaculum adriaticum JCM 14633T (98.0%). The average nucleotide identity (ANI) scores of strain S7007T with T. adriaticum JCM 14633T and T. maritimum NBRC 110778T were 78.3% and 77.1%, respectively and the Genome-to-Genome Distance Calculator (dDDH) scores were 20.5% and 19.9%, respectively. The sole isoprenoid quinone was MK-6 and the major cellular fatty acids (> 10.0%) were iso-C15:0, iso-C15:0 3-OH, iso-C15: 1 G and summed feature 3 (comprising C16:1 ω7c and/or C16:1 ω6c). The major polar lipids of strain S7007T were phosphatidylethanolamine, phosphatidyldimethylethanolamine, one unidentified lipid and two unidentified aminolipids. The genomic DNA G + C content was 30.9 mol %. The combined phenotypic data and phylogenetic inference that strain S7007T should be classified as a novel species in the genus Tenacibaculum, for which the name Tenacibaculum pelagium sp. nov. is proposed. The type strain is S7007T (= MCCC 1H00428T = KCTC 72941T).

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).

Planococcus maritimus ML1206 Isolated from Wild Oysters Enhances the Survival of Caenorhabditis elegans against Vibrio anguillarum.

With the widespread occurrence of aquaculture diseases and the broad application of antibiotics, drug-resistant pathogens have increasingly affected aquatic animals' health. Marine probiotics, which live under high pressure in a saltwater environment, show high potential as a substitute for antibiotics in the field of aquatic disease control. In this study, twenty strains of non-hemolytic bacteria were isolated from the intestine of wild oysters and perch, and a model of Caenorhabditis elegans infected by Vibrio anguillarum was established. Based on the model, ML1206, which showed a 99% similarity of 16S rRNA sequence to Planococcus maritimus, was selected as a potential marine probiotic, with strong antibacterial capabilities and great acid and bile salt tolerance, to protect Caenorhabditis elegans from being damaged by Vibrio anguillarum. Combined with plate counting and transmission electron microscopy, it was found that strain ML1206 could significantly inhibit Vibrio anguillarum colonization in the intestinal tract of Caenorhabditis elegans. Acute oral toxicity tests in mice showed that ML1206 was safe and non-toxic. The real-time qPCR results showed a higher expression level of genes related to the antibacterial peptide (ilys-3) and detoxification (ugt-22, cyp-35A3, and cyp-14A3) in the group of Caenorhabditis elegans protected by ML1206 compared to the control group. It is speculated that ML1206, as a potential probiotic, may inhibit the infection caused by Vibrio anguillarum through stimulating Caenorhabditis elegans to secrete antibacterial effectors and detoxification proteins. This paper provides a new direction for screening marine probiotics and an experimental basis to support the potential application of ML1206 as a marine probiotic in aquaculture.

Tichowtungia aerotolerans gen. nov., sp. nov., a novel representative of the phylum Kiritimatiellaeota and proposal of Tichowtungiaceae fam. nov., Tichowtungiales ord. nov. and Tichowtungiia class. nov.

Kiritimatiellaeota is widespread and ecologically important in various anoxic environments. However, the portion of culturable bacteria within this phylum is quite low and, in fact, there is only one currently described species. In this study, a novel anaerobic, non-motile, coccoid, Gram-stain-negative bacterial strain, designated S-5007T, was isolated from surface marine sediment. The 16S rRNA gene sequence was found to have very low 16S rRNA gene sequence similarity to the nearest known type strain, Kiritimatiella glycovorans L21-Fru-ABT (84.9 %). The taxonomic position of the novel isolate was investigated using a polyphasic approach and comparative genomic analysis. Phylogenetic analyses based on 16S rRNA genes and genomes indicated that strain S-5007T branched within the radiation of the phylum Kiritimatiellaeota. Different from the type strain, strain S-5007T can grow under microaerobic conditions, and the genomes of strain S-5007T and the other strains in its branch have many more antioxidant-related genes. Meanwhile, other different metabolic features deduced from genome analysis supported the separate evolution of the proposed class (strain S-5007T branch) and K. glycovorans L21-Fru-ABT. Based on phylogenetic and phenotypic characterization studies, Tichowtungia aerotolerans gen. nov., sp. nov. is proposed with S-5007T (=MCCC 1H00402T=KCTC 15876T) as the type strain, as the first representative of novel taxa, Tichowtungiales ord. nov., Tichowtungiaceae fam. nov. in Tichowtungiia class. nov.

Salinibius halmophilus gen. nov., sp. nov., isolated from a marine solar saltern.

A novel Gram-stain-negative, facultatively anaerobic, flagellated and spiral-shaped bacterium, designated WDS2A16AT was isolated from a marine solar saltern in Weihai, PR China. Growth was observed at 20-40 °C (optimal 33-37 °C), 1-15 % (w/v) NaCl (optimal 3-4 %) and pH 6.0-9.0 (optimal pH 7.5). Major cellular fatty acids (>10 %) were C18 : 1ω7c and C16 : 0. Phosphatidylglycerol, diphosphatidylglycerol and an unidentified glycolipid were detected as the predominant polar lipids. The sole respiratory quinone was Q-8. The DNA G+C content of strain WDS2A16AT was 48.5 mol%. The 16S rRNA gene sequence similarities of WDS2A16AT with other species were less than 91 %. The average nucleotide identity, in silico DNA-DNA hybridization and amino acid identity of strain WDS2A16AT with the most related strain Gynuella sunshinyii YC6258 T were 66.1, 19.3 and 48.1 %, respectively. Comparative analysis of 16S rRNA gene sequences and phenotypic characterization indicated that strain WDS2A16AT represents a novel species in a new genus, for which the name Salinibius halmophilus gen. nov., sp. nov. is proposed. The type strain is WDS2A16AT (=KCTC 52225T=MCCC 1H00139T).

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).

Pelagivirga dicentrarchi sp. nov., a member of the family Rhodobacteraceae isolated from the gut microflora of sea bass (Dicentrarchus labrax L.).

A Gram-stain negative, aerobic, non-flagellated, non-gliding, rod-shaped bacterium, designated strain YLY04T, was isolated from the gut microflora of a sea bass (Dicentrarchus labrax L.) collected from the coast of Yuanyao Wharf, Weihai, China. Growth was found to occur at pH 6.0-9.0 (optimum, 7.0-8.0), 4-37 °C (optimum, 28-30 °C) in the presence of 0-11.0% (w/v) NaCl (optimum, 3.0-4.0%). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YLY04T is closely related to Pelagivirga sediminicola BH-SD19T and Roseovarius antarcticus M-S13-148T. Strain YLY04T contains ubiquinone-10 as the sole respiratory quinone and summed feature 8 (C18:1ω7c and/or C18:1ω6c), cyclo-C19:0ω8c, C16:0 and 11-methyl-C18:1ω7c as the major fatty acids. The polar lipids of strain YLY04T were found to consist of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, an unidentified aminolipid, an unidentified phospholipid and three unidentified lipids. The DNA G+C content was determined to be 62.7 mol%. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis, indicated that strain YLY04T represents a novel species within the genus Pelagivirga, for which the name Pelagivirga dicentrarchi sp. nov. is proposed. The type strain is YLY04T (= MCCC 1H00334T = KCTC 62452T).

Corallincola holothuriorum sp. nov., a facultative anaerobe isolated from sea cucumber intestine.

Strain C4T, isolated from sea cucumber intestine in Weihai, Shandong, PR China, is a novel Gram-stain-negative, facultatively anaerobic, amphitrichously flagellated, short rod that grows as creamy white bacterial colonies on plates. Optimal growth of the strain was observed at 28-30 °C, pH 6.5-7.0 and at a concentration of 3 % NaCl. The G+C content of the genomic DNA was 49.0 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain C4T is a member of the genus Corallincola and was most similar to Corallincola platygyrae JLT2006T. The major cellular fatty acids of strain C4T were C16 : 1ω7c/iso-C15 : 0 2-OH, C16 : 0 and C18 : 1ω7c. The sole respiratory quinone was Q-8. The predominant polar lipids in strain C4T were phosphatidylethanolamine, phosphatidylglycerol and an unidentified phospholipid. Based on morphology and physiological characteristics, strain C4T should be classified as a novel species in the genus Corallincola, for which Corallincolaholothuriorum is proposed. The type strain is C4T (=ATCC BAA-2611T=CICC 10839T).

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).

Cohaesibacter celericrescens sp. nov., isolated from sea catfish.

A novel Gram-stain-negative, rod-shaped, ivory-white, facultatively anaerobic and catalase-positive bacterium, designated H1304T, was isolated from the gut of sea catfish from Coast of Weihai, China. Optimal growth occurred at 30-33 °C (range, 4-37 °C) and pH 7.0-7.5 (range, pH 6.5-9.0) with 2.0-3.0 % (w/v) NaCl (range, 0.5-4.0 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that H1304T belonged to the genus Cohaesibacter and was most closely related to Cohaesibactermarisflavi CGMCC 1.9157T (96.7 % 16S rRNA gene sequence similarity), Cohaesibactergelatinilyticus MCCC 1A02698T (96.3 %) and Cohaesibacterhaloalkalitolerans KCTC 32038T (96.0 %). The sole isoprenoid quinone was Q-10, the polar lipid profile consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylcholine, glycolipid, an unidentified phospholipid and an unidentified aminolipid. The major fatty acids (>10 %) were C18 : 1ω7c and summed feature 3 (C16 : 1ω7c/C16 : 1ω6c). The DNA G+C content of strain H1304T is 50.8 mol%. Based on the combination of phylogenetic analysis, phenotypic data and chemotaxonomic data, strain H1304T is considered to represent a novel species within the genus Cohaesibacter in the family Cohaesibacteraceae, for which the name Cohaesibacter celericrescens sp. nov. is proposed. The type strain of the new species is H1304T (=KCTC 62075T=MCCC 1H00241T).

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).

Flavihalobacter algicola gen. nov. sp. nov., a member of the family Flavobacteriaceae with alginate-degradation activity, isolated from marine alga Saccharina japonica.

A Gram-stain-negative, aerobic, yellow, non-motile, rod-shaped and alginate-degrading bacterium, designated Dm15T, was isolated from marine alga collected in Weihai, PR China. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain Dm15T represents a distinct line of the family Flavobacteriaceae. Strain Dm15T had the highest 16S rRNA gene sequence similarity to its closest phylogenetic neighbour Arcticiflavibacter luteus (96.7 %) and 93.7-96.4 % sequence similarity to other phylogenetic neighbours (Bizionia paragorgiae, Winogradskyella thalassocola, Ichthyenterobacterium magnum, Psychroserpens burtonensis and Arcticiflavibacter luteus) in the family Flavobacteriaceae. The novel isolate was able to grow at 10-40 °C (optimum, 30-33 °C), pH 7.0-9.0 (optimum, pH 7.0-7.5) and with 0.5-6.0 % NaCl (optimum 2.0-3.0 %, w/v). It could grow at 40 °C, and degrade alginate and cellulose, which were different from the neighbour genera. The draft genome consisted of 3395 genes with a total length of 3 798 431 bp and 34.1mol% G+C content. Especially, there were some specific genes coding for cellulase and alginate lyase, which provided a basis for the above phenotypic characteristics. The strain's genome sequence showed 71.1-80.2 % average amino acid identity values and 71.8-77.7 % average nucleotide identity values compared to the type strains of related genera within the family Flavobacteriaceae. It shared digital DNA-DNA hybridization identity of 19.8 and 20.9 % with I. magnum and A. luteus, respectively. The sole menaquinone was MK-6. The major fatty acids were iso-C15 : 0 and iso-C15 : 1 G. The polar lipids included six unidentified polar lipids, four unidentified aminolipids and phosphatidylethanolamine. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain Dm15T represents a novel species of a new genus in the family Flavobacteriaceae, phylum Bacteroidetes, for which the name Flavihalobacter algicola gen. nov., sp. nov. is proposed. The type strain is Dm15T (KCTC 42256T=CICC 23815T).

Vibrio albus sp. nov., isolated from marine sediment.

A Gram-stain-negative, facultative anaerobic, motile, slightly bent rod-shaped bacterium, designated strain E4404T, was isolated from coastal sediment sampled Weihai, China. According to phylogenetic analysis based on its 16S rRNA gene sequence, strain E4404T shared the highest similarity with the type strain of Vibriovariabilis (97.0 %), followed by the type strains of Vibriomaritimus (96.1 %) and Vibrioeuropaeus (96.0 %). Multilocus sequence analysis based on the 16S rRNA gene and eight housekeeping genes (ftsZ, gapA, gyrB, mreB, pyrH, recA, rpoA and topA) showed that strain E4404T formed a unique clade in the genus Vibrio. The average nucleotide identity and digital DNA-DNA hybridization values between strain E4404T and some other species in the genus Vibrio were 71.0-72.7 % and 20.4-22.4 %, respectively. Cells grew at 15-37 °C and pH 6.0-8.5 in the presence of 1.0-6.0 % (w/v) NaCl, with optimal growth at 33 °C and pH 7.0-7.5 in the presence of 3.0-3.5 % (w/v) NaCl. No growth was observed on thiosulfate citrate bile salts sucrose medium. The major fatty acids of strain E4404T were summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), C16 : 0 and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The genomic DNA G+C content of strain E4404T was 46.1 mol%. Based on the phylogenetic, genotypic, phenotypic, biochemical and chemotaxonomic characteristics, strain E4404T represented a novel species of the genus Vibrio, for which the name Vibrioalbus sp. nov. is proposed. The type strain is E4404T (=MCCC 1H00197T=KCTC 52890T).

Characterization of a highly stable α-galactosidase from thermophilic Rasamsonia emersonii heterologously expressed in a modified Pichia pastoris expression system.

BACKGROUND: Structurally stable α-galactosidases are of great interest for various biotechnological applications. More thermophilic α-galactosidases with high activity and structural stability have therefore to be mined and characterized. On the other hand, few studies have been performed to prominently enhance the AOX1 promoter activity in the commonly used Pichia pastoris system, in which production of some heterologous proteins are insufficient for further study. RESULTS: ReGal2 encoding a thermoactive α-galactosidase was identified from the thermophilic (hemi)cellulolytic fungus Rasamsonia emersonii. Significantly increased production of ReGal2 was achieved when ReGal2 was expressed in an engineered Pastoris pichia expression system with a modified AOX1 promoter and simultaneous fortified expression of Mxr1 that is involved in transcriptionally activating AOX1. Purified ReGal2 exists as an oligomer and has remarkable thermo-activity and thermo-tolerance, exhibiting maximum activity of 935 U/mg towards pNPGal at 80 °C and retaining full activity after incubation at 70 °C for 60 h. ReGal2 is insensitive to treatments by many metal ions and exhibits superior tolerance to protein denaturants. Moreover, ReGal2 efficiently hydrolyzed stachyose and raffinose in soybeans at 70 °C in 3 h and 24 h, respectively. CONCLUSION: A modified P. pichia expression system with significantly enhanced AOX1 promoter activity has been established, in which ReGal2 production is markedly elevated to facilitate downstream purification and characterization. Purified ReGal2 exhibited prominent features in thermostability, catalytic activity, and resistance to protein denaturants. ReGal2 thus holds great potential in relevant biotechnological applications.