Oricola nitratireducens sp. nov., a novel nitrate reducing bacterium isolated from marine sediment in East China Sea.

A novel strain designated NBU1457T, was isolated from marine sediment sampled on Meishan Island located in the East China Sea. Cells of strain NBU1457T was Gram-negative, facultatively anaerobic, non-motile and ovoid-shaped. Strain NBU1457T grew optimally at 37 °C, NaCl concentration of 2.0-3.0% (w/v) and pH 6.5-7.5. Catalase and oxidase activities, urease, nitrate reduction and H2S production were positive. Indole production, methyl red reaction, hydrolysis of starch, gelatin, casein, Tweens 20, 40, 60 and 80 were negative. Comparative analysis of the 16S rRNA gene sequence showed highest similarities to the species with validated name Oricola thermophila MEBiC13590T (98.8%), Oricola cellulosilytica CC-AMH-0 T (97.9%) and Oricola indica JL-62 T (97.9%). Phylogenetic analyses indicated that strain NBU1457T clustered with the genus Oricola and closely related to strains Oricola thermophila MEBiC13590T, Oricola cellulosilytica CC-AMH-0 T and Oricola indica JL-62 T. The average nucleotide identity and digital DNA-DNA hybridization values between strain NBU1457T and related species of genus Oricola were well below the threshold limit for prokaryotic species delineation. The DNA G + C content was 63.2%. The major cellular fatty acid was summed feature 8 (C18:1 ω7c and/or C18:1 ω6c). The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylmonomethylethanolamine, sulfoquinovosyldiacylglycerol and phosphatidylglycerol. The only respiratory quinone was ubiquinone-10 (Q-10). Combining results of our phenotypic, chemotaxonomic and genotypic data, strain NBU1457T is considered to be a representative in the genus Oricola, which the name Oricola nitratireducens sp. nov. is proposed. The type strain of the new species is NBU1457T (= KCTC 82225 T = MCCC 1K04764T).

Luteolibacter marinus sp. nov., a novel bacterium in the family Verrucomicrobiaceae, isolated from marine sediment.

A Gram-negative, rod-shaped, non-motile and strictly aerobic bacterium, designated NBU1238T, was isolated from marine sediment sampled on Meishan Island located in the East China Sea. Strain NBU1238T was able to grow optimally at 28-32 °C, at pH 7.5 and with no NaCl. Catalase and oxidase activities, H2S production and hydrolysis of Tweens 40 and 60 were positive. Methyl red reaction, Voges-Proskauer test and hydrolysis of starch, casein and Tweens 20 and 80 were negative. The major cellular fatty acids were iso-C14 : 0, C16 : 0, C16 : 1 ω9c and C14 : 0. The only respiratory quinone was menaquinone-9. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylmethylethanolamine. The 16S rRNA gene sequence of strain NBU1238T showed 95.6, 95.6, 94.8 and 93.8% sequence similarity to Luteolibacter flavescens GKXT, Luteolibacter luteus G-1-1-1T, Luteolibacter arcticus MC 3726T and Luteolibacter pohnpeiensis A4T-83T, respectively. Phylogenetic analyses indicated that strain NBU1238T clustered with the genus Luteolibacter and was closely related to strains L. flavescens GKXT, L. arcticus MC 3726T and L. luteus G-1-1-1T. The average nucleotide identity and digital DNA-DNA hybridization values between strain NBU1238T and related species of genus Luteolibacter were well below the threshold limit for prokaryotic species delineation. The DNA G+C content of the genomic DNA was 65.0 mol%. Based on its phenotypic, chemotaxonomic and genotypic data, strain NBU1238T is considered to be a representative of a novel species in the genus Luteolibacter, for which the name Luteolibacter marinus sp. nov. is proposed. The type strain is NBU1238T (=KCTC 82227T=MCCC 1K04772T).

Nisaea sediminum sp. nov., a heavy metal resistant bacterium isolated from marine sediment in the East China Sea.

A Gram-negative, rod-shaped, motile and strictly aerobic bacterium, designated NBU1469T, was isolated from marine sediment sampled on Meishan Island located in the East China Sea. Strain NBU1469T grew optimally at temperature of 40 °C, NaCl concentration of 2.0% (w/v) and pH 7.5. Catalase and oxidase activities, H2S production, nitrate reduction and hydrolysis of Tween 20 were positive. Indole, methyl red reaction, urease, hydrolysis of gelatin, starch, casein, Tweens 40, 60 and 80 were negative. The major cellular fatty acids were C16:0, C19:0 cyclo ω8c and summed feature 8 (C18:1 ω7c and/or C18:1 ω6c). The only respiratory quinone was ubiquinone-10 (Q-10). The major polar lipids were phosphatidylglycerol, two unidentified amino-phospholipids and two unidentified phospholipids. Comparative analysis of the 16S rRNA gene sequence showed highest similarities to the species with validated name Nisaea nitritireducens DR41_18T (98.1%) and Nisaea denitrificans DR41_21T (97.6%). Phylogenetic analyses indicated that strain NBU1469T formed a distinct lineage with strains Nisaea nitritireducens DR41_18T and Nisaea denitrificans DR41_21T within the genus Nisaea. The average nucleotide identity and digital DNA-DNA hybridization values between strain NBU1469T and related species of genus Nisaea were well below the threshold limit for prokaryotic species delineation. The DNA G + C content was 63.6%. Based on its phenotypic, chemotaxonomic and genotypic data, strain NBU1469T is considered to be a representative of a novel species in the genus Nisaea, for which the name Nisaea sediminum sp. nov. is proposed. The type strain is NBU1469T (=KCTC 82224 T =MCCC 1K04763T).

Microbulbifer hainanensis sp. nov., a moderately halopilic bacterium isolated from mangrove sediment.

A new bacterium was successfully isolated from a mangrove sediment sample in Haikou City, Hainan Province, China. The organism is a Gram-negative, rod-shaped, non-motile and strictly aerobic bacterium, named NBU-8HK146T. Strain NBU-8HK146T was able to grow at temperatures of 10-40 °C, at salinities of 0-11% (w/v) and at pH 5.5-9.5. Veoges-Proskauer, methyl red reaction and hydrolysis of Tween 20 were negative. Catalase and oxidase activities, H2S production, hydrolysis of starch, casein, Tweens 40, 60 and 80 were positive. The major cellular fatty acids were C16:0, iso-C15:0 and summed feature 9. The major respiratory quinone was ubiquinone-8 (Q-8). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and two unidentified glycolipids. According to 16S rRNA gene sequence similarities, strain NBU-8HK146T shared 98.0%, 97.9%, 97.7%, 97.6% and 97.3% similarities to the species with validated name Microbulbifer taiwanensis CC-LN1-12T, Microbulbifer rhizosphaerae Cs16bT, Microbulbifer marinus Y215T, Microbulbifer donghaiensis CN85T and Microbulbifer aggregans CCB-MM1T, respectively. Phylogenetic analyses indicated that strain NBU-8HK146T formed a distinct lineage with strains Microbulbifer taiwanensis CC-LN1-12T and Microbulbifer marinus Y215T. Both digital DNA-DNA hybridization values (19.5-22.7%) and average nucleotide identity values (73.2-78.9%) between strain NBU-8HK146T and related species of genus Microbulbifer were below the species delineation cutoffs. The DNA G+C content was 58.9 mol%. Many proteins involving in the adaption of osmotic stress in the salt environment of mangrove were predicted in genome of strain NBU-8HK146T. From phenotypic, genotypic, phylogenetic and chemotaxonomic characteristics, strain NBU-8HK146T can be regarded as a new Microbulbifer species for which the name Microbulbifer hainanensis. The type strain is NBU-8HK146T (= KCTC 82226T = MCCC 1K04737T).

Reg2 treatment is protective but the induced Reg2 autoantibody is destructive to the islets in NOD mice.

Regenerating family protein 2 (Reg2) is a trophic factor which stimulates ß-cell replication and resists islet destruction. However, Reg2 also serves as an islet autoantigen, which makes it complicated to judge the effectiveness in treating diabetes. How Reg2 treatment behaves in non-obese diabetic (NOD) mice is to be investigated. NOD mice were treated with recombinant Reg2 protein, Complete Freund's adjuvant (CFA) + PBS and CFA+Reg2 vaccinations, CFA+PBS- and CFA+Reg2-immunized antisera, and single chain variable fragment (scFv)-Reg2 and mIgG2a-Reg2 antibodies. Glycemic level, bodyweight, serum Reg2 antibody titer, glucose tolerance, and insulin secretion were determined. Islet morphological characteristics, insulitis, cell apoptosis, islet cell components, and T cell infiltration were analyzed by histological examinations. The autoantigenicity of constructed Reg2C and Reg2X fragments was determined in healthy BALB/c mice, and the bioactivity in stimulating cell proliferation and survival was assessed in insulinoma MIN6 cells. Reg2 administration alleviated diabetes in NOD mice with improved glucose tolerance and insulin secretion but elevated serum Reg2 autoantibodies. Histomorphometry showed reduced inflammatory area, TUNEL signal and CD8 + T cell infiltration, and increased ß-cell proportion in support of the islet-protective effect of Reg2 treatment. CFA+PBS and CFA+Reg2 immunizations prevented diabetic onset and alleviated insulitis while injections of the antisera offered mild protections. Antibody treatments accelerated diabetic onset without increasing the overall incidence. Reg2C fragment depletes antigenicity, but reserves protective activity in streptozotocin (STZ)-treated MIN6 cells. In conclusion, Reg2 treatment alleviates type 1 diabetes (T1D) by preserving islet ß-cells, but induces Reg2 autoantibody production which poses a potential risk of accelerating diabetic progression.