Discovery of supercritical carbon dioxide in a hydrothermal system.

Supercritical CO2 appearing as bubbles in hydrothermal vents was identified in the south part of the Okinawa Trough using in situ Raman spectroscopy. Significantly, the N2 peak in supercritical CO2 is much larger than those in seawater and vent fluids, indicating that supercritical CO2 enriches N2 from the surrounding environment. Considering that the partial pressures of CO2 and N2 in the Earth's proto-atmosphere were ~10-20 MPa, supercritical CO2 with high N2 was likely the dominant CO2 phase near the water-air interface in the early history of the Earth, which promoted the synthesis, pre-enrichment and preservation of amino acids and other organic matters that are essential to the origin of life.

Marinobacter fonticola sp. nov., isolated from deep sea cold seep sediment.

In this study, we report a novel Gram-negative bacterium, designated as strain CS412T, isolated from deep-sea sediment collected in a cold seep area of the South China Sea. Growth of strain CS412T occurred at 4-40 °C (optimum, 28 °C), pH 5.0-11.0 (optimum, pH 6.0) and with 0-19 % (w/v) NaCl (optimum, 1-2 %). Phylogenetic analysis based on 16S rRNA gene sequence data indicated that strain CS412T belonged to the genus Marinobacter. The closest phylogenetic neighbours of strain CS412T were Marinobacter pelagius HS225T (96.9 %), Marinobacter szutsaonensis NTU-104T (96.8%), Marinobacter santoriniensis NKSG1T (96.4%) and Marinobacter koreensisdd-M3T (96.3 %). The genomic DNA G+C content of strain CS412T was 58.0 mol%. The principal respiratory quinone was ubiquinone-9 (Q-9). The polar lipids of CS412T contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, aminophospholipidand and four glycolipids. The major fatty acids of CS412T contained cyclo-C19 : 0ω8c, C16 : 0, C18 : 1ω7c and C18 : 1ω7c 11-methyl. The results of phylogenetic, physiological, biochemical and morphological analyses suggested that strain CS412T represents a novel species of the genus Marinobacter, and the name Marinobacter fonticola sp. nov. is proposed with the type species CS412T (=CCTCC AB 2019197T=KCTC 72475T).

High temperature-induced proteomic and metabolomic profiles of a thermophilic Bacillus manusensis isolated from the deep-sea hydrothermal field of Manus Basin.

Thermophiles are organisms that grow optimally at 50 °C-80 °C and studies on the survival mechanisms of thermophiles have drawn great attention. Bacillus manusensis S50-6 is the type strain of a new thermophilic species isolated from hydrothermal vent in Manus Basin. In this study, we examined the growth and global responses of S50-6 to high temperature on molecular level using multi-omics method (genomics, proteomics, and metabolomics). S50-6 grew optimally at 50 °C (Favorable, F) and poorly at 65 °C (Non-Favorable, NF); it formed spores at F but not at NF condition. At NF condition, S50-6 formed long filaments containing undivided cells. A total of 1621 proteins were identified at F and NF conditions, and 613 proteins were differentially expressed between F and NF. At NF condition, proteins of glycolysis, rRNA mature and modification, and DNA/protein repair were up-regulated, whereas proteins of sporulation and amino acid/nucleotide metabolism were down-regulated. Consistently, many metabolites associated with amino acid and nucleotide metabolic processes were down-regulated at NF condition. Our results revealed molecular strategies of deep-sea B. manusensis to survive at unfavorable high temperature and provided new insights into the thermotolerant mechanisms of thermophiles. SIGNIFICANCE: In this study, we systematically characterized the genomic, proteomic and metabolomic profiles of a thermophilic deep-sea Bacillus manusensis under different temperatures. Based on these analysis, we propose a model delineating the global responses of B. manusensis to unfavorable high temperature. Under unfavorable high temperature, glycolysis is a more important energy supply pathway; protein synthesis is subjected to more stringent regulation by increased tRNA modification; protein and DNA repair associated proteins are enhanced in production to promote heat survival. In contrast, energy-costing pathways, such as sporulation, are repressed, and basic metabolic pathways, such as amino acid and nucleotide metabolisms, are slowed down. Our results provide new insights into the thermotolerant mechanisms of thermophilic Bacillus.

Description of Bacillus kexueae sp. nov. and Bacillus manusensis sp. nov., isolated from hydrothermal sediments.

Two Gram-staining-positive, strictly aerobic bacilli, designated as strains Ma50-5T and Ma50-6T, were isolated from the hydrothermal sediments of Manus Basin in the western Pacific Ocean. Based on 16S rRNA gene sequence, strains Ma50-5T and Ma50-6T were most closely related to Bacillus alveayuensis (97.0 and 97.2 % identity, respectively). The 16S rRNA gene sequence identity between strains Ma50-5T and Ma50-6T was 97.4 %. The identities between strains Ma50-5T and Ma50-6T and other closely related organisms were below 97.0 %. The G+C contents of the genomic DNA of strains Ma50-5T and Ma50-6T were 43.4 and 47.6 mol%, respectively. The major fatty acids (>10 %) of both strains were iso-C15 : 0 and iso-C17 : 0. The predominant isoprenoid quinone detected in both strains was menaquinone-7. Phylogenetic, physiological, biochemical and morphological analyses suggested that strains Ma50-5T and Ma50-6T represent two novel species of the genus Bacillus, for which the names Bacillus kexueae sp. nov. (type strain Ma50-5T=KCTC 33881T=CCTCC AB 2017020T) and Bacillus manusensis sp. nov. (type strain Ma50-6T=KCTC 33882T=CCTCC AB 2017019T), respectively, are proposed.

Comparative transcriptome analysis of Rimicaris sp. reveals novel molecular features associated with survival in deep-sea hydrothermal vent.

Shrimp of the family Alvinocarididae are the predominant megafauna of deep-sea hydrothermal vents. However, genome information on this family is currently unavailable. In the present study, by employing Illumina sequencing, we performed the first de novo transcriptome analysis of the gills of the shrimp Rimicaris sp. from the hydrothermal vent in Desmos, Manus Basin. The analysis was conducted in a comparative manner with the shrimp taken directly from the vent (GR samples) and the shrimp that had been maintained for ten days under normal laboratory condition (mGR samples). Among the 128,938 unigenes identified, a large number of differentially expressed genes (DEGs) between the GR and mGR samples were detected, including 2365 and 1607 genes significantly upregulated and downregulated, respectively, in GR. The DEGs covered diverse functional categories. Most of the DEGs associated with immunity were downregulated in GR, while most of the DEGs associated with sulfur metabolism and detoxification were upregulated in GR. These results provide the first comprehensive transcriptomic resource for hydrothermal vent Rimicaris and revealed varied categories of genes likely involved in deep-sea survival.