Marinicellulosiphila megalodicopiae gen. nov., sp. nov., a deep-sea alkaliphilic cellulolytic bacterium isolated from an endemic ascidian Megalodicopia hians

The strain TOYAMA8T is a deep-sea alkaliphilic cellulolytic bacterium isolated from a slurry-adhered epiphytic site of Megalodicopia hians. Cells of this strain are Gram-negative, aerobic, curved rods or spirilla, motile with monopolar flagella, and grow on cellulose as the sole carbon source. Compared to other closely related species, this bacterium is characterized by a large number of cellulase genes. Strain TOYAMA8T showed alkaliphilic growth within the pH range 7.5-9.0. The major cellular fatty acids were C18 : 1 ω7, C14 : 0, C16 : 0 and C16 : 1 ω7. The major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, unidentified phospholipids and aminolipids. A major respiratory lipoquinone was Q-9. Phylogenomic analysis using the 16S rRNA gene and whole-genome sequence data showed that the strain is related to the families Gynuellaceae, Saccharospirillaceae and Natronospirillaceae. The values of 16S rRNA gene sequence similarity, amino acid identity and percentage of conserved proteins between the strain TOYAMA8T and related species were low, with maximum values of 90.6, 48.1 and 34.6%, respectively. These results, together with differences in phenotypic and biochemical characteristics, indicate that the new isolate TOYAMA8T represents a novel genus and species, for which the name Marinicellulosiphila megalodicopiae gen. nov., sp. nov., is proposed. The type strain is TOYAMA8T (JCM 31119T=DSM 114864T).

Reinekea thalattae sp. nov., a New Species of the Genus Reinekea Isolated from Surface Seawater in Sehwa Beach

A Gram-stain-negative, non-pigmented, curved rod-shaped, single polarly flagellated, facultatively anaerobic bacterium, designated as SSH23^T, was isolated from surface seawater sample collected at the Sehwa Beach in South Korea. The novel isolate required NaCl for growth and grew optimally between 2 and 3% NaCl. Strain SSH23^T showed high 16S rRNA gene sequence similarities with Reinekea marinisedimentorum DSM 15388^T (96.4%), Reinekea marina KACC 17315^T (96.2%), Reinekea blandensis KACC 17315^T (95.9%) and Reinekea aestuarii KCTC 22813^T (95.6%). The major polar lipids of strain SSH23^T were phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The major cellular fatty acids of strain SSH23^T were C_16:0, summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c), and summed feature 8 (C_18:1 ω7c and/or C_18:1 ω6c). The predominant respiratory quinone was found to be ubiquinone-8. The average nucleotide identity values of strain SSH23^T with R. marinisedimentorum DSM 15388^T and R. blandensis MED297^T were determined to be 72.2% and 69.8%, respectively. The G+C content of the genomic DNA was 45.5 mol%. Based on genotypic, phenotypic, chemotaxonomic, and phylogenetic analyses, strain SSH23^T was considered to represent a novel member of the genus Reinekea, for which the name Reinekea thalattae sp. nov. is proposed. The type strain of Reinekea thalattae is SSH23^T (= KACC 21168^T = NBRC 113795^T).

Bacterial biofilm development during experimental degradation of Melicertus kerathurus exoskeleton in seawater

Chitinolytic bacteria are widespread in marine and terrestrial environment, and this is rather a reflection of their principle growth substrate's ubiquity, chitin, in our planet. In this paper, we investigated the development of naturally occurring bacterial biofilms on the exoskeleton of the shrimp Melicertus kerathurus during its degradation in sea water. During a 12-day experiment with exoskeleton fragments in batch cultures containing only sea water as the growth medium at 18 °C in darkness, we analysed the formation and succession of biofilms by scanning electron microscopy and 16S rRNA gene diversity by next generation sequencing. Bacteria belonging to the γ- and α-Proteobacteria and Bacteroidetes showed marked (less or more than 10%) changes in their relative abundance from the beginning of the experiment. These bacterial taxa related to known chitinolytic bacteria were the Pseudolateromonas porphyrae, Halomonasaquamarina, Reinekea aestuarii, Colwellia asteriadis and Vibrio crassostreae. These bacteria could be considered as appropriate candidates for the degradation of chitinous crustacean waste from the seafood industry as they dominated in the biofilms developed on the shrimp's exoskeleton in natural sea water with no added substrates and the degradation of the shrimp exoskeleton was also evidenced.

Reinekea marina sp. nov., isolated from seawater, and emended description of the genus Reinekea

A Gram-stain-negative, curved rod-shaped and non-pigmented strain, HME8277T, was isolated from surface seawater of the Yellow Sea in the Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences showed that the novel strain was related most closely to Reinekea blandensis MED297T (96.4 % 16S rRNA gene sequence similarity), Reinekea aestuarii IMCC4489T (96.3 %) and Reinekea marinisedimentorum KMM 3655T (95.8 %). The major fatty acids were summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c; 43.0 %), C16 : 0 (19.0 %) and summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1ω6c; 15.0 %). The DNA G+C content was 46.1 mol%. The predominant respiratory quinone was Q-8. The major polar lipids of strain HME8277T comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, four unidentified phospholipids and four unidentified lipids. On the basis of polyphasic analyses, strain HME8277T represents a novel species of the genus Reinekea, for which the name Reinekea marina sp. nov. is proposed. The type strain HME8277T ( = KACC 17315T = CECT 8288T). An emended description of the genus Reinekea is also provided.

Salinispirillum marinum gen. nov., sp. nov., a haloalkaliphilic bacterium in the family ‘Saccharospirillaceae’

A novel Gram-staining-negative, motile, non-pigmented, facultatively anaerobic, spirillum-shaped, halophilic and alkaliphilic bacterium, designated strain GCWy1T, was isolated from water of the coastal–marine wetland Gomishan in Iran. The strain was able to grow at NaCl concentrations of 1–10 % (w/v) and optimal growth was achieved at 3 % (w/v). The optimum pH and temperature for growth were pH 8.5 and 30 °C, while the strain was able to grow at pH 7.5–10 and 4–40 °C. Phylogenetic analysis based on the comparison of the 16S rRNA gene sequence placed the isolate within the class Gammaproteobacteria as a separate deep branch, with 92.1 % or lower sequence similarity to representatives of the genera Saccharospirillum and Reinekea and less than 91.0 % sequence similarity with other remotely related genera. The major cellular fatty acids of the isolate were C18 : 1ω7c, C16 : 0 and C17 : 0, and the major components of its polar lipid profile were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The cells of strain GCWy1T contained the isoprenoid quinones Q-9 and Q-8 (81 % and 2 %, respectively). The G+C content of the genomic DNA of this strain was 52.3 mol%. On the basis of 16S rRNA gene sequence analysis in combination with chemotaxonomic and phenotypic data, strain GCWy1T represents a novel species in a new genus in the family ‘ Saccharospirillaceae ’, order Oceanospirillales , for which the name Salinispirillum marinum gen. nov., sp. nov. is proposed. The type strain of the type species is GCWy1T ( = IBRC-M 10765T = CECT 8342T).

Litoribrevibacter albus gen. nov. sp. nov., isolated from coastal seawater, Fujian Province, China

A Gram-stain negative, short rod-shaped aerobic bacterium with flagella, designated strain Y32(T), was isolated from coastal seawater in Xiamen, Fujian Province of China. 16S rRNA gene sequence comparisons showed that strain Y32(T) is a member of the family Oceanospirillaceae, forming a distinct lineage with species of the genus Litoribacillus. The 16S rRNA gene sequence similarities between strain Y32(T) and other strains were all less than 94.0 %. Strain Y32(T) was found to grow optimally at 28 °C, at pH 7.0-8.0 and in the presence of 4-5 % (w/v) NaCl. The major fatty acids were identified as Summed Feature 3 (comprising C16:1 ω7c and/or C16:1 ω6c, 49.4 %), C16:0 (17.7 %), C14:0 (6.9 %) and C18:1 ω9c (5.4 %). The major respiratory quinone was identified as ubiquinone-8 (Q-8). The major polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content of strain Y32(T) was determined to be 55.6 mol%. According to its morphology, physiology, fatty acid composition, polar lipids composition and 16S rRNA gene sequence data, strain Y32(T) represents a novel species of a new genus in the family Oceanospirillaceae, for which the name Litoribrevibacter albus gen. nov. sp. nov. is proposed. The type strain of Litoribrevibacter albus is Y32(T) (=MCCC 1F01211(T)=NBRC 110071(T)).

Purification and characterization of β-mannanase from Reinekea sp. KIT-YO10 with transglycosylation activity

Marine bacterium Reinekea sp. KIT-YO10 was isolated from the seashore of Kanazawa Port in Japan as a seaweed-degrading bacterium. Homology between KIT-YO10 16S rDNA and the 16S rDNA of Reinekea blandensis and Reinekea marinisedimentorum was 96.4 and 95.4%, respectively. Endo-1,4-β-D-mannanase (β-mannanase, EC 3.2.1.78) from Reinekea sp. KIT-YO10 was purified 29.4-fold to a 21% yield using anion exchange chromatography. The purified enzyme had a molecular mass of 44.3 kDa, as estimated by SDS-PAGE. Furthermore, the purified enzyme displayed high specificity for konjac glucomannan, with no secondary agarase and arginase activity detected. Hydrolysis of konjac glucomannan and locust bean gum yielded oligosaccharides, compatible with an endo mode of substrate depolymerization. The purified enzyme possessed transglycosylation activity when mannooligosaccharides (mannotriose or mannotetraose) were used as substrates. Optimal pH and temperature were determined to be 8.0 and 70 °C, respectively. It showed thermostability at temperatures from 20 to 50 °C and alkaline stability up to pH 10.0. The current enzyme was thermostable and thermophile compared to the β-mannanase of other marine bacteria.