Tepidibacillus marianensis sp. nov., a novel heterotrophic iron-reducing bacterium isolated from Mariana Trench sediment.

A novel chemoheterotrophic iron-reducing micro-organism, designated as strain LSZ-M11000T, was isolated from sediment of the Marianas Trench. Phylogenetic analysis based on the 16S rRNA gene revealed that strain LSZ-M11000T belonged to genus Tepidibacillus, with 97 % identity to that of Tepidibacillus fermentans STGHT, a mesophilic bacterium isolated from the Severo-Stavropolskoye underground gas storage facility in Russia. The polar lipid profile of strain LSZ-M11000T consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, as well as other unidentified phospholipids and lipids. The major fatty acids were C16 : 0 (28.4 %), C18 : 0 (15.8 %), iso-C15 : 0 (12.9 %), and anteiso-C15 : 0 (12.0 %). Strain LSZ-M11000T had no menaquinone. Genome sequencing revealed that the genome size of strain LSZ-M11000T was 2.97 Mb and the DNA G+C content was 37.9 mol%. The average nucleotide identity values between strain LSZ-M11000T and its close phylogenetic relatives, Tepidibacillus fermentans STGHT and Tepidibacillus decaturensis Z9T, were 76.4 and 72.6 %, respectively. The corresponding DNA-DNA hybridization estimates were 20.9 and 23.4 %, respectively. Cells of strain LSZ-M11000T were rod-shaped (1.0-1.5×0.3-0.5 µm). Using pyruvate as an electron donor, it was capable of reducing KMnO4, MnO2, As(V), NaNO3, NaNO2, Na2SO4, Na2S2O3, and K2Cr2O7. Based on phenotypic, genotypic, and phylogenetic evidence, strain LSZ-M11000T is proposed to be a novel strain of the genus Tepidibacillus, for which the name Tepdibacillus marianensis is proposed. The type strain is LSZ-M11000T (=CCAM 1008T=JCM 39431T).

Characterization and Biosynthetic Regulation of Isoflavone Genistein in Deep-Sea Actinomycetes Microbacterium sp. B1075.

Deep-sea environments, as relatively unexplored extremes within the Earth's biosphere, exhibit notable distinctions from terrestrial habitats. To thrive in these extreme conditions, deep-sea actinomycetes have evolved unique biochemical metabolisms and physiological capabilities to ensure their survival in this niche. In this study, five actinomycetes strains were isolated and identified from the Mariana Trench via the culture-dependent method and 16S rRNA sequencing approach. The antimicrobial activity of Microbacterium sp. B1075 was found to be the most potent, and therefore, it was selected as the target strain. Molecular networking analysis via the Global Natural Products Social Molecular Networking (GNPS) platform identified 25 flavonoid compounds as flavonoid secondary metabolites. Among these, genistein was purified and identified as a bioactive compound with significant antibacterial activity. The complete synthesis pathway for genistein was proposed within strain B1075 based on whole-genome sequencing data, with the key gene being CHS (encoding chalcone synthase). The expression of the gene CHS was significantly regulated by high hydrostatic pressure, with a consequent impact on the production of flavonoid compounds in strain B1075, revealing the relationship between actinomycetes' synthesis of flavonoid-like secondary metabolites and their adaptation to high-pressure environments at the molecular level. These results not only expand our understanding of deep-sea microorganisms but also hold promise for providing valuable insights into the development of novel pharmaceuticals in the field of biopharmaceuticals.

Effects of Epigenetic Modification and High Hydrostatic Pressure on Polyketide Synthase Genes and Secondary Metabolites of Alternaria alternata Derived from the Mariana Trench Sediments.

The hadal biosphere is the most mysterious ecosystem on the planet, located in a unique and extreme environment on Earth. To adapt to extreme environmental conditions, hadal microorganisms evolve special strategies and metabolisms to survive and reproduce. However, the secondary metabolites of the hadal microorganisms are poorly understood. In this study, we focused on the isolation and characterization of hadal fungi, screening the potential strains with bioactive natural products. The isolates obtained were detected further for the polyketide synthase (PKS) genes. Two isolates of Alternaria alternata were picked up as the representatives, which had the potential to synthesize active natural products. The epigenetic modifiers were used for the two A. alternata isolates to stimulate functional gene expression in hadal fungi under laboratory conditions. The results showed that the chemical epigenetic modifier, 5-Azacytidine (5-Aza), affected the phenotype, PKS gene expression, production of secondary metabolites, and antimicrobial activity of the hadal fungus A. alternata. The influence of epigenetic modification on natural products was strongest when the concentration of 5-Aza was 50 µM. Furthermore, the modification of epigenetic agents on hadal fungi under high hydrostatic pressure (HHP) of 40 MPa displayed significant effects on PKS gene expression, and also activated the production of new compounds. Our study demonstrates the high biosynthetic potential of cultivable hadal fungi, but also provides evidence for the utility of chemical epigenetic modifiers on active natural products from hadal fungi, providing new ideas for the development and exploitation of microbial resources in extreme environments.

Cellulomonas aurantiaca Kim et al. 2020 is a later heterotypic synonym of Cellulomonas algicola Yamamura et al. 2019.

Cellulomonas algicola KZ-21T was compared with Cellulomonas aurantiaca THG-SMD2.3T to examine the taxonomic relationship between the two type strains. The 16S rRNA gene sequence of Cellulomonas algicola KZ-21T shared complete similarity (100.0 %) with that of Cellulomonas aurantiaca THG-SMD2.3T. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the two strains formed a tight cluster within the genus Cellulomonas. Genome comparison between the two strains revealed an average nucleotide identity of 99.2 % and a digital DNA-DNA hybridization estimate of 93.7±1.8 %, strongly indicating that the two strains belong to a single species. In addition, neither strain displayed any striking differences in metabolic, physiological or chemotaxonomic features. Therefore, we propose Cellulomonas aurantiaca as a later heterotypic synonym of Cellulomonas algicola.

Hanstruepera crassostreae He et al. 2018 is a later heterotypic synonym of Pseudobizionia ponticola Park et al. 2018.

Hanstruepera crassostreae L53T was compared with Pseudobizionia ponticola MM-14T to examine the taxonomic relationship between the two type strains. The 16S rRNA gene sequence of H. crassostreae L53T had complete similarity (100.0%) to that of P. ponticola MM-14T. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the two strains formed a tight cluster within the genus Pseudobizionia. Draft genomic comparison between the two strains revealed an average nucleotide identity of 96.9 % and a digital DNA-DNA hybridization estimate of 75.3±2.8 %, strongly indicating that the two strains represented a single species. In addition, neither strain displayed any striking difference in metabolic, physiological or chemotaxonomic features. Therefore, we propose that Hanstruepera crassostreae is a later heterotypic synonym of Pseudobizionia ponticola.

Nonomuraea nitratireducens Qu et al. 2020 is a later heterotypic synonym of Nonomuraea phyllanthi Klykleung et al. 2020.

Nonomuraea nitratireducens WYY166T was compared with Nonomuraea phyllanthi PA1-10T to examine the taxonomic relationship between the two type strains. The 16S rRNA gene sequence of N. nitratireducens WYY166T had high similarity (99.9 %) to that of N. phyllanthi PA1-10T. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the two strains formed a tight cluster within the genus Nonomuraea. Draft genomic comparison between the two strains revealed an average nucleotide identity of 99.3 % and a digital DNA-DNA hybridization estimate of 94.4±1.8 %, strongly indicating that the two strains represented a single species. In addition, neither strain displayed any striking difference in metabolic, physiological or chemotaxonomic features. Therefore, we propose Nonomuraea nitratireducens as a later heterotypic synonym of Nonomuraea phyllanthi.

Evidence for Long-Term Anthropogenic Pollution: The Hadal Trench as a Depository and Indicator for Dissemination of Antibiotic Resistance Genes.

Knowledge of the distribution and dissemination of antibiotic resistance genes (ARGs) is essential for understanding anthropogenic impacts on natural ecosystems. The transportation of ARGs via aquatic environments is significant and has received great attention, but whether there has been anthropogenic ARG pollution to the hadal ocean ecosystem has not been well explored. For investigating ecological health concerns, we profiled the ARG occurrence in sediments of the Mariana Trench (MT) (10 890 m), the deepest region of the ocean. Metagenomic-based ARG profiles showed a sudden increase of abundance and diversity in the surface layer of MT sediments reaching 2.73 × 10-2 copy/cell and 81 subtypes, and a high percentage of ∼63.6% anthropogenic pollution sources was predicted by the Bayesian-modeling classification method. These together suggested that ARG accumulation and anthropogenic impacts have already permeated into the bottom of the deepest corner on the earth. Moreover, six ARG-carrying draft genomes were retrieved using a metagenomic binning strategy, one of which assigned as Streptococcus was identified as a potential bacterial host to contribute to the ARG accumulation in MT, carrying ermF, tetM, tetQ, cfxA2, PBP-2X, and PBP-1A. We propose that the MT ecosystem needs further long-term monitoring for the assessment of human impacts, and our identified three biomarkers (cfxA2, ermF, and mefA) could be used for the rapid monitoring of anthropogenic pollution. Together our findings imply that anthropogenic pollution has penetrated into the deepest region of the ocean and urge for better pollution control to reduce the risk of ARG dissemination to prevent the consistent accumulation and potential threat to the natural environment.

Metabacillus sediminilitoris sp. nov., a marine bacterium isolated from a tidal sediment.

A Gram-stain-positive, endospore-forming, motile and rod-shaped bacterium, designated as strain DSL-17T, was isolated from a tidal sediment of the East China Sea and characterized phylogenetically and phenotypically. The strain could grow at 16-47 °C (optimum 37 °C), at pH 6.0-10.0 (optimum 6.0) and with 1-7% (w/v) NaCl (optimum 3 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain DSL-17T was related to members of the genus Metabacillus and shared the highest similarity with Metabacillus litoralis SW-211T (98.6 %), followed by Metabacillus halosaccharovorans E33T (97.9 %), Metabacillus crassostreae JSM 100118T (97.7 %), Metabacillus niabensis 4T19T (97.7 %) and Metabacillus malikii NCCP-662T (97.5 %). 16S rRNA gene sequence similarities between strain DSL-17T and other members of the genus Metabacillus were below 96.6 %. The sole respiratory quinone was MK-7. Strain DSL-17T had a cell-wall peptidoglycan based on meso-diaminopimelic acid. The polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), three unidentified glycolipids and six unidentified lipids. The strain had iso-C15 : 0, anteiso-C15 : 0, iso-C14 : 0, C16 : 0 and iso-C16 : 0 as major fatty acids. The G+C content of the genomic DNA was 35.7 mol%. The combined genotypic and phenotypic data indicated that strain DSL-17T represents a novel species of the genus Metabacillus, for which the name Metabacillus sediminilitoris sp. nov. is proposed The type strain is DSL-17T (=MCCC 1K03777T=DSM 109843T).

Halomonas piezotolerans sp. nov., a multiple-stress-tolerant bacterium isolated from a deep-sea sediment sample of the New Britain Trench.

A piezotolerant, H2O2-tolerant, heavy-metal-tolerant, slightly halophilic bacterium (strain NBT06E8T) was isolated from a deep-sea sediment sample collected from the New Britain Trench at depth of 8900 m. The strain was aerobic, motile, Gram-stain-negative, rod-shaped, oxidase-positive and catalase-positive. Growth of the strain was observed at 4-45 °C (optimum, 30 °C), at pH 5-11 (optimum, pH 8-9) and in 0.5-21 % (w/v) NaCl (optimum, 3-7 %). The optimum pressure for growth was 0.1-30 MPa with tolerance up to 60 MPa. Under optimum growth conditions, the strain could tolerate 15 mM H2O2. Resuls of 16S rRNA gene sequence analysis showed that strain NBT06E8T is closely related to Halomonas aquamarina DSM 30161T (99.5%), Halomonas meridiana DSM 5425T (99.43%) and Halomonas axialensis Althf1T (99.35%). The digital DNA-DNA hybridization values between strain NBT06E8T and the three related type strains, H. aquamarina, H. meridiana and H. axialensis, were 30.5±2.4 %, 30.7±2.5% and 31.5±2.5 %, respectively. The average nucleotide identity values between strain NBT06E8T and the three related type strains were 86.26, 86.26 and 83.63 %, respectively. The major fatty acids were summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) and C16 : 0. The predominant respiratory quinone detected was ubiquinone-9 (Q-9). Based on its phenotypic and phylogenetic characteristics, we conclude that strain NBT06E8T represents a novel species of the genus Halomonas, for which the name Halomonas piezotolerans sp. nov. is proposed (type strain NBT06E8T= MCCC 1K04228T=KCTC 72680T).

Muricauda hadalis sp. nov., a novel piezophile isolated from hadopelagic water of the Mariana Trench and reclassification of Muricauda antarctica as a later heterotypic synonym of Muricauda teanensis.

A novel marine Gram-stain-negative, non-motile, aerobic and rod-shaped bacterium, designated as strain MT-229T, was isolated from the deep seawater in the Mariana Trench and characterized phylogenetically and phenotypically. Bacterial optimal growth occurred at 30 °C (ranging 10-40 °C), pH 6 (ranging 3-11) and with 11 % (w/v) NaCl (ranging 0-17 %). Strain MT-229T was a piezophile, growing optimally at 20 MPa (range 0.1-70 MPa). The nearest phylogenetic neighbours were Muricauda antarctica CGMCC 1.2174T and Muricauda taeanensis JCM 17757T with 16S rRNA gene similarity of 98.7 %. The sole respiratory quinone was menaquinone-6 (MK-6). The major polar lipids were phosphatidylethanolamine (PE), two unidentified aminolipids (AL) and ten unidentified lipids. The major fatty acids of strain MT-229T were iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1 G. The G+C content of the genomic DNA was 45.6 mol%. The combined genotypic and phenotypic data indicated that strain MT-229T represents a novel species of the genus Muricauda, for which the name Muricauda hadalis sp. nov. is proposed, with the type strain MT-229T (=DSM 109894T=MCCC 1K04201T). In addition, the whole-genome-based comparisons revealed that the type strains of Muricauda antarctica and Muricauda teanensis belong to a single species. It is, therefore, proposed that M. antarctica be recognized as a heterotypic synonym of M. teanensis.

Georhizobium profundi gen. nov., sp. nov., a piezotolerant bacterium isolated from a deep-sea sediment sample of the New Britain Trench.

A novel alphaproteobacterium, strain WS11T, was isolated from a deep-sea sediment sample collected from the New Britain Trench. The full-length 16S rRNA gene of strain WS11T had the highest sequence similarity of 97.6 % to Rhizobium subbaraonis JC85T, followed by Mycoplana ramosa DSM 7292T (96.9 %) and Rhizobium azooxidifex Po 20/26T (96.8 %). Phylogenetic analysis of concatenated 16S rRNA, atpD and recA gene sequences showed that strain WS11T was deeply separated from the species within the family Rhizobiaceae. Phylogenomic analysis based on the whole-genome protein sequences showed that strain WS11T formed an independent monophyletic branch in the family Rhizobiaceae, paralleled with the species in the families Brucellaceae and Phyllobacteriaceae within the order Rhizobiales. Cells were Gram-stain-negative, oxidase- and catalase-positive, and aerobic short rods (1.5-2.4×0.9-1.0 µm). Growth was observed at salinities ranging from 0 to 5% (optimum, 1 %), from pH 6.5 to 9 (optimum, pH 7) and at temperatures between 20 and 30 °C (optimum, 28 °C). Strain WS11T was piezotolerant, growing optimally at 0.1 MPa (range 0.1-70 MPa). The main fatty acid was summed feature 8 (C18 : 1 ω7c/C18  : 1 ω 6c). The sole respiratory quinone was ubiquinone-10 (Q-10). The predominant polar lipids were phosphatidylcholine, two unidentified aminophospholipids and an unidentified phospholipid. The genome size was about 4.36 Mbp and the G+C content was 62.3 mol%. The combined genotypic and phenotypic data show that strain WS11T represents a novel species of a novel genus in the family Rhizobiaceae, for which the name Georhizobium profundi gen. nov., sp. nov. is proposed (type strain WS11T=MCCC 1K03498T=KCTC 62439T).

Occurrence of Halogenated Organic Pollutants in Hadal Trenches of the Western Pacific Ocean.

The hadal trenches are the most remote and inaccessible habitats on earth and were once believed to be pristine. A recent study has reported the detection of high levels of persistent organic pollutants (POPs), including polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs), in endemic amphipods from two hadal trenches (Mariana and Kermadec) in the Western Pacific, implicating that the trenches are indeed polluted. However, a fundamental question remains unanswered, if and to what extent such the physical environment of the trenches is polluted by POPs. In this study, we sampled Mariana, Mussau, and New Britain trenches and analyzed samples of amphipods, sediment, and suspended particulate matter (SPM). Our results show that the amphipods contained elevated levels of PCBs and PBDEs, comparable to those reported in the earlier study. We also detected significantly high concentrations (up to 1343 ng g-1 lw) of chlorinated pesticides, such as dichlorodiphenyltrichloroethanes and chlordanes. Furthermore, four brominated natural products (BNPs), which structurally resembled methoxylated brominated diphenyl ethers or polybrominated biphenyls, were identified in the endemic amphipods. However, neither POPs nor BNPs were detected in sediments or SPM. Taken together, we propose that the POPs detected in endemic amphipods likely resulted from bioaccumulation by feeding on polluted large detritus (e.g., carrion) falling to the trench bottoms from the surface ocean.

Confluentibacter sediminis sp. nov., isolated from the junction between the ocean and a freshwater lake and emended description of the genus Confluentibacter.

A novel marine Gram-stain-negative, non-motile, aerobic and rod-shaped bacterium, designated strain DSL-48T, was isolated from tidal flat sediment sampled from the East China Sea and characterized phylogenetically and phenotypically. Bacterial optimal growth occurred at 35 °C (range, 4-37 °C), pH 6 (pH 5-10) and with 4 % (w/v) NaCl (0-7 %). The nearest phylogenetic neighbour was Confluentibacter citreus KCTC 52638T with 16S rRNA gene similarity of 97.1 %. The predominant respiratory quinone was menaquinone-6 (MK-6). The major polar lipids were phosphatidylethanolamine, three unidentified aminolipids and four unidentified lipids. The major fatty acids of strain DSL-48T were iso-C15 : 0, iso-C17 : 0 3-OH, anteiso-C15 : 0, iso-C15 : 0 3-OH and iso-C16 : 0 3-OH. The G+C content of the genomic DNA was 33.3 mol%. The combined genotypic and phenotypic data indicated that strain DSL-48T represents a novel species of the genus Confluentibacter, for which the name Confluentibacter sediminis sp. nov. is proposed, with the type strain DSL-48T (=KCTC 62648T=MCCC 1K03537T).

Alteromonas indica Lin et al. 2018 is a later heterotypic synonym of Salinimonas sediminis Cao et al. 2018.

Alteromonas indica IO390401T was compared with Salinimonas sediminis N102T to examine the taxonomic relationship between the two type strains. The 16S rRNA gene sequence of A. indica IO390401T shared high similarity (99.9 %) with that of S. sediminis N102T. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the two strains formed a tight cluster within the genus Salinimonas. Whole genomic comparison between the two strains revealed an average nucleotide identity of 99.2 % and a digital DNA-DNA hybridization estimate of 92.6 %, strongly indicating that the two strains represented a single species. In addition, neither strain displayed any striking difference in metabolic, physiological or chemotaxonomic features. Therefore, we propose Alteromonas indica as a later heterotypic synonym of Salinimonas sediminis.

Marinomonas shanghaiensis sp. nov., isolated from the junction between an ocean and a freshwater lake.

A Gram-stain-negative, motile with single polar flagellum, rod-shaped bacterium, designated as strain DSL-35T, was isolated from the location where the ocean and Dishui lake meet at Shanghai on the East China Sea and characterized phylogenetically and phenotypically. Optimal growth occurred at 35 °C (range, 4-40 °C), pH 8 pH 5-11) and with 3-4 % (w/v) NaCl (0-12 %). Phylogenetic analysis based on its 16S rRNA gene sequence showed that strain DSL-35T was related to members of the genus Marinomonas and shared the highest sequence identities with Marinomonasarctica 328T (98.0 %), Marinomonashwangdonensis HDW-15T (97.5 %) and Marinomonasrhizomae IVIA-Po-145T (97.2 %). The 16S rRNA gene sequence identities between strain DSL-35T and other members of the genus Marinomonas were below 96.8 %. The digital DNA-DNA hybridization values between strain DSL-35T and the three type strains, Marinomonas. arctica 328T, M. rhizomae HDW-15T and M. rhizomae IVIA-Po-145T, were 30.9±2.4 %, 21.7±2.2% and 22±2.3 %, respectively. The average nucleotide identity values between strain DSL-35T and the three type strains were 87.6 %, 84.6 and 84.2 %, respectively. The predominant ubiquinone was Q-8. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. The predominant cellular fatty acids of strain DSL-35T were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c; 40.0 %), C16 : 0 (22.5 %), summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 11.2 %), summed feature 2 (C14 : 0 3-OH and/or iso I C16 : 1; 7.2 %), C14 : 0 (6.8 %) and C12 : 0 (5.2 %). The G+C content of the genomic DNA was 44.5 mol%. The combined genotypic and phenotypic data indicated that strain DSL-35T represents a novel species of the genus Marinomonas, for which the name Marinomonas shanghaiensis sp. nov. is proposed, with the type strain DSL-35T (=KCTC 62646T=MCCC 1K03535T).

Paracoccus sediminilitoris sp. nov., isolated from a tidal flat sediment.

A novel marine Gram-stain-negative, non-spore-forming, motile, aerobic, coccoid or ovoid bacterium, designated as strain DSL-16T, was isolated from a tidal flat sediment on the East China Sea and characterized phylogenetically and phenotypically. Optimal growth of the strain occurred at 35 °C (range 4-40 °C), at pH 6 (range 5-11) and with 4 % (w/v) NaCl (range 1-14 %). The nearest phylogenetic neighbour was Paracoccusseriniphilus DSM 14827T (98.2 % 16S rRNA gene sequence similarity). The digital DNA-DNA hybridization value between strain DSL-16T and P. seriniphilus DSM 14827T was 19.5±2.2 %. The average nucleotide identity value between strain DSL-16T and P. seriniphilus DSM 14827T was 83.6 %. The sole respiratory ubiquinone was Q-10. The major polar lipids were phosphatidylmonomethylethanolamine (PME), phosphatidylglycerol (PG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), diphosphatidyglycerol (DPG) and glycolipid (GL). The predominant cellular fatty acids of strain DSL-16T were C18 : 1ω7c, C18 : 0 and 11-methyl C18 : 1ω7c. The G+C content of the genomic DNA was 64.5 mol%. The combined genotypic and phenotypic data indicated that strain DSL-16T represents a novel species of the genus Paracoccus, for which the name Paracoccus sediminilitoris sp. nov. is proposed. The type strain is DSL-16T (=KCTC 62644T=MCCC 1K03534T).

Marinobacter profundi sp. nov., a slightly halophilic bacterium isolated from a deep-sea sediment sample of the New Britain Trench.

A piezotolerant, cold-adapted, slightly halophilic bacterium, designated strain PWS21T, was isolated from a deep-sea sediment sample collected from the New Britain Trench. Cells were observed to be Gram-stain negative, rod-shaped, oxidase- and catalase-positive. Growth of the strain was observed at 4-45 °C (optimum 37 °C), at pH 5.0-9.0 (optimum 7.0) and in 0.5-20% (w/v) NaCl (optimum 3-4%). The optimum pressure for growth was 0.1 MPa (megapascal) with tolerance up to 70 MPa. 16S rRNA gene sequence analysis showed that strain PWS21T is closely related to Marinobacter guineae M3BT (98.4%) and Marinobacter lipolyticus SM19T (98.2%). Multilocus sequence analysis (MLSA) based on sequences of housekeeping genes gyrB, recA, atpD, rpoB and rpoD indicates that strain PWS21T represents a distinct evolutionary lineage within the genus Marinobacter. Furthermore, strain PWS21T showed low ANI and diDDH values to the closely related species. The principal fatty acids were identified as C12:0, C12:0 3-OH, C16:1ω9c, C16:0 and C18:1ω9c. Ubiquinone-9 was identified as the major respiratory quinone. The polar lipids were identified as phosphatidylethanolamine (PE), phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), aminophospholipid (APL), two unidentified lipids and an unidentified phospholipid (PL). The G + C content of the genomic DNA was determined to be 60.3 mol%. On the basis of phenotypic, chemotaxonomic and molecular data, we conclude that strain PWS21T represents a novel species of the genus Marinobacter, for which the name Marinobacter profundi sp. nov. is proposed (type strain PWS21T = KCTC 52990T = MCCC 1K03345T).

Algoriphagus litoralis sp. nov., isolated from the junction between the ocean and a freshwater lake.

A Gram-stain negative, non-motile and short rod shaped bacterium, designated strain DSL-12T, was isolated from seawater of the East China Sea and characterised phylogenetically and phenotypically. Optimal growth was found to occur at 28 °C (range 4-40 °C), pH 7 (range 6-12) and with 3% (w/v) NaCl (range 0-8%). Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain DSL-12T is related to members of the genus Algoriphagus and shares high sequence similarities with Algoriphagus boritolerans DSM 17298T (97.6%) and Algoriphagus alkaliphilus DSM 22703T (97.6%). The 16S rRNA gene sequence identities between strain DSL-12T and other current members of the genus Algoriphagus were below 96.4%. The digital DNA-DNA hybridization values between strain DSL-12T and the type strains A. boritolerans DSM 17298T and A. alkaliphilus DSM 22703T were found to be 21.2 ± 2.4% and 20.2 ± 2.4%, respectively. The average nucleotide identity (ANI) values between strain DSL-12T and A. boritolerans DSM 17298T and A. alkaliphilus DSM 22703T were found to be 83.2% and 82.8%, respectively. The sole respiratory quinone was identified as MK-7. The major polar lipids were identified as phosphatidylethanolamine, diphosphatidylglycerol, one unidentified phospholipid and two unidentified lipids. The major fatty acids identified as were iso-C15:0, summed feature 8 (C18:1ω7c and/or C18:1ω6c), C16:0, summed feature 3 (C16:1ω7c and/or C16:1ω6c) and iso-C17:0. The G+C content of the genomic DNA was determined to be 43.3 mol%. The combined genotypic and phenotypic data indicate that strain DSL-12T represents a novel species of the genus Algoriphagus, for which the name Algoriphagus litoralis sp. nov. is proposed, with the type strain DSL-12T (= KCTC 62647T = MCCC 1K03536T).

Corynebacterium hadale sp. nov. isolated from hadopelagic water of the New Britain Trench.

A novel heterotrophic, Gram-stain-positive, facultatively anaerobic and rod-shaped bacterium, designated strain NBT06-6T, was isolated from the deep seawater in the New Britain Trench and characterized phylogenetically and phenotypically. Optimal bacterial growth occurred at 35 °C (range 22-41 °C), at pH 6 (4-8) and with 4 % (w/v) NaCl (0-10 %). The strain grew at hydrostatic pressures of 0.1-100 MPa (optimum, 0.1 MPa) at 35 °C. Phylogenetic analysis of the 16S rRNA gene sequences indicated that strain NBT06-6T belonged to the genus Corynebacterium, with the highest sequence similarity (97.9 %) to Corynebacterium imitans, and shared low 16S rRNA gene sequence similarities (<97.0 %) with other type strains. The major respiratory menaquinones were MK-8(H2) and MK-9(H2). The polar lipids were diphosphatidyglycerol, phosphatidylglycerol, phosphatidylinositol, three unidentified aminoglycolipids and four unidentified glycolipids. The major fatty acids detected were C18 : 1ω9c, C16 : 0 and C15 : 0. Strain NBT06-6T contained meso-diaminopimelic acid and mycolic acids in its cell wall, and mannose, galactose, glucose, arabinose and ribose as major whole-cell sugars. The G+C content of the genomic DNA was 65.1 mol%. The digital DNA-DNA hybridization value and the average nucleotide identity between strain NBT06-6T and C. imitans were 24.5±2.4 and 81.9 %, respectively. The combined genotypic and phenotypic data indicated that strain NBT06-6T represents a novel species of the genus Corynebacterium, for which the name Corynebacterium hadale sp. nov. is proposed, with the type strain NBT06-6T (=MCCC 1K03347T=DSM 105365T).

Salinimonas sediminis sp. nov., a piezophilic bacterium isolated from a deep-sea sediment sample from the New Britain Trench.

A cold-adapted, piezophilic, slightly halophilic bacterium, designated as N102T, was isolated from a deep-sea (4700 m) sediment sample collected from the New Britain Trench. Strain N102T was Gram-stain-negative, rod-shaped, oxidase- and catalase-positive, and grew optimally at 28 °C (range, 4-40 °C), pH 7.0-7.5 (range, 6.0-9.0) and 3-4 %(w/v) NaCl (range, 2-15 %). The optimum pressure for growth was 10 MPa with tolerance up to 70 MPa. 16S rRNA gene sequence analysis showed that strain N102T was most closely related to Alteromonas addita R10SW13T (97.2 %), Alteromonas stellipolaris LMG 21861T (97.1 %), Alteromonas gracilis 9a2T (97.1 %), Salinimonas lutimaris DPSR-4T (96.1 %) and Salinimonas chungwhensis BH030046T (95.4 %). Phylogenetic analyses based on 16S rRNA gene, gyrB gene and whole-genome sequences placed strain N102T within the genus Salinimonas. Genomic comparisons based on average nucleotide identity and tetranucleotide signature frequencies corroborated the results of the phylogenetic analyses. The principal fatty acids were summed feature 3 (C16 : 1ω7c/C16 : 1ω6c), C16 : 0 and summed feature 8 (C18 : 1ω7c/C18 : 1ω6c). The major respiratory quinone was ubiquinone 8. The predominant polar lipids were phosphatidylethanolamine, phosphatidylglycerol and an unidentified phospholipid. The G+C content of the genomic DNA was 48.2 mol%. On the basis of phenotypic, chemotaxonomic and molecular data, we conclude that strain N102T represents a novel species of the genus Salinimonas, for which the name Salinimonassediminis sp. nov. is proposed (type strain N102T=MCCC 1K03497T=KCTC 62440T).