Mesonia profundi sp. nov., isolated from deep-sea sediment of the Mariana Trench.

A Gram-stain-negative, aerobic, rod-shaped, non-flagellated, non-gliding bacterial strain, designated MT50T, was isolated from a deep-sea sediment sample collected from the Mariana Trench. Optimal growth of strain MT50T was observed at 25 °C, pH 7.0-7.5 and in the presence of 3-5 % (w/v) NaCl. The strain was positive for oxidase and catalase. Phylogenetic analysis of 16S rRNA gene sequences revealed that strain MT50T is affiliated with the genus Mesonia, showing the highest sequence similarity (98.5 %) to the type strain of Mesonia ostreae. The digital DNA-DNA hybridization and average nucleotide identity values between strain MT50T and four closely related type strains of known Mesonia species (14.1-54.8 % and 72.7-86.8 %, respectively) were all below the threshold values to discriminate bacterial species, indicating that strain MT50T is affiliated with a novel species within the genus. The genomic G+C content deduced from the genome of strain MT50T was 36.2 mol%. The major fatty acids of strain MT50T were iso-C15 : 0, iso-C17 : 0 3-OH and anteiso-C15 : 0. The predominant respiratory quinone of the strain was MK-6. The polar lipids of strain MT50T included phosphatidylethanolamine and two unidentified lipids. Based on the polyphasic data presented in this study, strain MT50T represents a novel species of the genus Mesonia, for which the name Mesonia profundi sp. nov. is proposed. The type strain is MT50T (=MCCC 1K07833T=KCTC 92380T).

Characteristics and Application of a Novel Cold-Adapted and Salt-Tolerant Protease EK4-1 Produced by an Arctic Bacterium Mesonia algae K4-1.

Mesonia algae K4-1 from the Arctic secretes a novel cold-adapted and salt-tolerant protease EK4-1. It has the highest sequence similarity with Stearolysin, an M4 family protease from Geobacillus stearothermophilus, with only 45% sequence identity, and is a novel M4 family protease. Ek4-1 has a low optimal catalytic temperature (40 °C) and is stable at low temperatures. Moreover, EK4-1 is still active in 4 mol/L NaCl solution and is tolerant to surfactants, oxidizing agents and organic solvents; furthermore, it prefers the hydrolysis of peptide bonds at the P1' position as the hydrophobic residues, such as Leu, Phe and Val, and amino acids with a long side chain, such as Phe and Tyr. Mn2+and Mg2+ significantly promoted enzyme activity, while Fe3+, Co+, Zn2+ and Cu2+ significantly inhibited enzyme activity. Amino acid composition analysis showed that EK4-1 had more small-side-chain amino acids and fewer large-side-chain amino acids. Compared with a thermophilic protease Stearolysin, the cold-adapted protease EK4-1 contains more random coils (48.07%) and a larger active pocket (727.42 Å3). In addition, the acidic amino acid content of protease EK4-1 was higher than that of the basic amino acid, which might be related to the salt tolerance of protease. Compared with the homologous proteases EB62 and E423, the cold-adapted protease EK4-1 was more efficient in the proteolysis of grass carp skin, salmon skin and casein at a low temperature, and produced a large number of antioxidant peptides, with DPPH, ·OH and ROO· scavenging activities. Therefore, cold-adapted and salt-tolerant protease EK4-1 offers wide application prospects in the cosmetic and detergent industries.

Mesonia aestuariivivens sp. nov., isolated from a tidal flat.

A Gram-negative, aerobic, non-flagellated and ovoid or rod-shaped bacterial strain (JHPTF-M18T), which was isolated from a tidal flat sediment in Republic of Korea, was taxonomically characterized. Strain JHPTF-M18T grew optimally at 25 °C, at pH 7.0-7.5 and in the presence of 2.0-3.0% (w/v) NaCl. 16S rRNA gene sequence analysis showed that strain JHPTF-M18T forms a phylogenetic lineage within the radiation comprising type strains of Mesonia species. The 16S rRNA gene of strain JHPTF-M18T shared sequence similarities of 97.7% with that of type strain of M. mobilis and 92.5-96.8% with those of type strains of the other nine Mesonia species. The DNA G+C content was 33.1% based on its genomic sequence. AAI, ANI and dDDH values between strain JHPTF-M18T and the type strains of M. mobilis, M. hitae, M. oceanica, M. phycicola and M. algae were 72.1-83.7%, 73.1-79.7% and 18.5-22.8%, respectively. Strain JHPTF-M18T contained MK-6 as the predominant menaquinone and iso-C15:0, iso-C17:0 3-OH and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c) as its major fatty acids. Major polar lipids of strain JHPTF-M18T were phosphatidylethanolamine and two unidentified lipids. Strain JHPTF-M18T was separated from recognized Mesonia species by its phenotypic properties together with the phylogenetic and genetic distinctiveness. Based on data presented in this study, strain JHPTF-M18T is considered to represent a novel species of the genus Mesonia. The name Mesonia aestuariivivens sp. nov. is proposed for JHPTF-M18T (=KACC 22185T = NBRC 115119T).

Mesonia hitae sp. nov., isolated from the seawater of the South Atlantic Ocean.

A Gram-negative, non-motile, non-spore-forming, aerobic and short rod-shaped bacterial strain R32T, was isolated from seawater of the South Atlantic Ocean. Strain R32T grew at 10-40 °C (optimum 28 °C), at pH 6.0-8.0 (optimum 7.0), and in the presence of 3-8 % NaCl (w/v) (optimum 5 %). Cells were oxidase- and catalase-positive. The 16S rRNA gene sequence of strain R32T shared the highest similarities with Mesonia oceanica (98.3 %), followed by Salegentibacter salarius (93.0 %), Salegentibacter mishustinae (92.8 %), Salegentibacter salegens (92.5 %) and Mesonia maritima (92.4 %). The dominant fatty acids were iso-C15 : 0 (32.7 %) and iso-C17 : 0 3-OH (21.1 %). Menaquinone-6 (MK-6) was detected as the sole respiratory quinone. The polar lipids found were phosphatidylethanolamine, three aminolipids and three unidentified lipids. The DNA G+C content was 35.0 mol%. The ANI value and dDDH value between strain R32T and the Salegentibacter and Mesonia species were 70.5-85.8 % and 18.7-30.5 %, respectively. Based on the results of the polyphasic characterization, strain R32T is considered to represent a novel species of the genus Mesonia, for which the name Mesonia hitae sp. nov. is proposed. The type strain is R32T (=MCCC 1A09780T=KCTC 72004T).

Temporal differences in microbial composition of Époisses cheese rinds during ripening and storage.

Époisses is a protected designation of origin smear-ripened cheese from the Burgundy region in France. It has an orange color and a strong flavor, both of which are generated by surface microorganisms. The objective of the present study was to investigate the microbial dynamics at the surface of Époisses cheese during ripening and postmanufacturing storage at low temperatures. Rind samples were analyzed by enumeration on agar plates and by 16S rRNA gene and internal transcribed spacer amplicon sequencing. During most of the ripening process, the counts of yeasts, which corresponded to the species Debaryomyces hansenii and Geotrichum candidum, were higher than those of the aerobic acid-sensitive bacteria. Debaryomyces hansenii reached a level of about 3 × 108 cfu/cm2, and its viability strongly decreased in the late stage of ripening and during storage at 4°C. Two of the inoculated bacterial species, Brevibacterium aurantiacum and Staphylococcus xylosus, did not establish themselves at the cheese surface. At the end of ripening, among the 18 most abundant bacterial species detected by amplicon sequencing, 14 were gram-negative, mainly from genera Psychrobacter, Vibrio, Halomonas, and Mesonia. It was hypothesized that the high moisture level of the Époisses rinds, due the humid atmosphere of the ripening rooms and to the frequent washings of the curds, favored growth of these gram-negative species. These species may be of interest for the development of efficient ripening cultures. In addition, because the orange color of Époisses cheeses could not be attributed to the growth of Brevibacterium, it would be interesting to investigate the type and origin of the pigments that confer color to this cheese.

Mesonia oceanica sp. nov., isolated from oceans during the Tara oceans expedition, with a preference for mesopelagic waters.

Strain ISS653T, isolated from Atlantic seawater, is a yellow pigmented, non-motile, Gram-reaction-negative rod-shaped bacterium, strictly aerobic and chemoorganotrophic, slightly halophilic (1-15 % NaCl) and mesophilic (4-37 °C), oxidase- and catalase-positive and proteolytic. Its major cellular fatty acids are iso-C15 : 0, iso-C15 : 0 2-OH, and iso-C17 : 0 3-OH; the major identified phospholipid is phosphatidylethanolamine and the major respiratory quinone is MK6. Genome size is 4.28 Mbp and DNA G+C content is 34.9 mol%. 16S rRNA gene sequence similarity places the strain among members of the family Flavobacteriaceae, with the type strains of Mesonia phycicola (93.2 %), Salegentibacter mishustinae (93.1 %) and Mesonia mobilis (92.9 %) as closest relatives. Average amino acid identity (AAI) and average nucleotide identity (ANI) indices show highest values with M. mobilis (81 % AAI; 78.9 % ANI), M. phycicola (76 % AAI; 76.3 % ANI), Mesonia maritima (72 % AAI, 74.9 % ANI), Mesonia hippocampi (64 % AAI, 70.8 % ANI) and Mesonia algae (68 % AAI; 72.2 % ANI). Phylogenomic analysis using the Up-to-date-Bacterial Core Gene set (UBCG) merges strain ISS653T in a clade with species of the genus Mesonia. We conclude that strain ISS653T represents a novel species of the genus Mesonia for which we propose the name Mesonia oceanica sp. nov., and strain ISS653T (=CECT 9532T=LMG 31236T) as the type strain. A second strain of the species, ISS1889 (=CECT 30008) was isolated from Pacific Ocean seawater. Data obtained throughout the Tara oceans expedition indicate that the species is more abundant in the mesopelagic dark ocean than in the photic layer and it is more frequent in the South Pacific, Indian and North Atlantic oceans.

Genome Sequencing of Mesonia algae K4-1 Reveals Its Adaptation to the Arctic Ocean.

The special ecological environment of the Arctic has brought about a large number of salt-tolerant and psychrotolerant microorganisms. We isolated two culturable bacterial strains of the genus Mesonia; one from the Arctic ocean, Mesonia algae K4-1, and one from the tropical sea, Mesonia sp. HuA40. Our genome analysis and phenotypic experiments indicated that Mesonia algae K4-1 is a moderately halophilic and psychrophilic bacterium. Mesonia algae K4-1 can tolerate 3-14% NaCl and grow at a wide range of temperatures from 4 to 50°C. Mesonia sp. HuA40 is a mesophilic bacterium that can only grow with 3-9% NaCl. In addition, the salt adaptation strategy of Mesonia algae K4-1 accumulates organic osmolytes in the cell. RNA helicases, glutathione and organic compatible solutes may play important roles in maintaining the metabolism and physiological function of Mesonia algae K4-1 under cold stress. Moreover, the ability of Mesonia algae K4-1 to adapt to an oligotrophic marine environment is likely due to the synthesis of a large number of extracellular polysaccharides and the secretion of various families of extracellular proteases. This study systematically analyzed the relationship between genomic differentiation and environmental factors of the Mesonia genus and revealed the possible adaptation mechanism of Mesonia algae K4-1 in the extreme Arctic marine environment at the genomic level.

Mesonia sediminis sp. nov., isolated from a sea cucumber culture pond.

A yellow-pigmented, Gram-stain negative and facultatively anaerobic bacterium, designated MF326(T), was isolated from a sample of sediment collected from a sea cucumber culture pond in Rongcheng, China (122°14'34″E 36°54'36″N). Cells of strain MF326(T) were found to be catalase negative and oxidase positive. Optimal growth was found to occur at 30 °C and pH 7.0-7.5 in the presence of 2.0-3.0% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MF326(T) is a member of the genus Mesonia and exhibits the high sequence similarity (94.3%) with the type strain of Mesonia ostreae, followed by Mesonia algae (93.9%). The dominant fatty acids of strain MF326(T) were identified as iso-C(15:0), an unidentified fatty acid with an equivalent chain-length of 13.565 and anteiso-C(15:0). The major polar lipids were found to be two unidentified lipids and phosphatidylethanolamine. The major respiratory quinone was found to be MK-6 and the genomic DNA G+C content was determined to be 40.7 mol%. On the basis of the phylogenetic analysis and differential phenotypic characteristics, it is concluded that strain MF326(T) (=KCTC 42255(T) =MCCC 1H00125(T)) should be assigned to the genus Mesonia as the type strain of a novel species, for which the name Mesonia sediminis sp. nov. is proposed.