Actinoflavosides B-D, Flavonoid Type Glycosides from Tidal Mudflat-Derived Actinomyces.

Three new secondary metabolites, actinoflavosides B-D (1-3), were discovered in the culture broth of two actinomycete strains (JML48 and JMS33) that were isolated from tidal mudflat sediment in Muan, Republic of Korea. The planar structures of the actinoflavosides were elucidated by MS, UV, and NMR analyses. The stereochemistry of an aminosugar, 2,3,6-trideoxy-3-amino-ribopyranoside in the actinoflavosides was determined by J-based configuration analysis using values obtained from DQF-COSY experiments and modified Mosher's method. Actinoflavosides B-D (1-3) displayed antibacterial activity against Pseudomonas aeruginosa, and actinoflavoside D (3) significantly increased IL-2 production in mouse splenocytes.

Roseibium limicola sp. nov., isolated from tidal mudflat.

A novel bacterium, designated strain CAU 1637T, was isolated from a tidal mudflat. Cells of strain CAU 1637T were Gram-stain-negative, aerobic, motile with single flagellum and rod-shaped. The optimum conditions for growth were observed at 30 °C, pH 6.0 and in the presence of 2 % (w/v) NaCl. The respiratory quinone was ubiquinone-10. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain CAU 1637T was closely related to the genus Roseibium, with the highest similarity to Roseibium aestuarii NRBC 112946T (97.4 %), followed by Roseibium hamelinense NRBC 16783T (96.8 %), Roseibium aquae JCM 19310T (96.4 %), Roseibium sediminis KCTC 52373T (95.8 %) and Roseibium denhamense JCM 10543T (95.3 %). The predominant cellular fatty acids were C18 : 1 ω7c 11-methyl and summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c). The major polar lipids consisted of diphosphatidylglycerol and phosphatidylglycerol. The average nucleotide identity values between the novel isolate and related strains ranged from 71.0 to 76.4 %, and the DNA-DNA hybridization values ranged from 19.3 to 20.3 %. The G+C content was 58.4 mol% and the whole-genome size was 4.6 Mb, which included 17 contigs and 3931 protein-coding genes. Based on the taxonomic data, strain CAU 1637T represents a novel species of the genus Roseibium, for which the name Roseibium limicola sp. nov. is proposed. The type strain is CAU 1637T (=KCTC 82429T=MCCC 1K06080T).

Marimonas lutisalis sp. nov., isolated from a tidal mudflat and emended description of the genus Marimonas.

A Gram-reaction-negative bacterial strain, designated GH1-19T, was isolated from a tidal mudflat sample collected in Gangwha Island, Republic of Korea. Cells of the novel micro-organism were strictly aerobic, non-sporulating, motile and rod-shaped. Growth occurred at 10-40 °C (optimum, 30 °C), pH 6-9 (pH 8) and in the presence of 1-9 % NaCl (3 %). Comparative analysis of complete or nearly complete 16S rRNA gene sequences exhibited that strain GH1-19T formed a distinct cluster between Marimonas arenosa CAU 1311T (97.42 % sequence similarity) and Aquicoccus porphyridii L1 8-17T (97.35 %). Similarity levels of 16S rRNA gene sequences between the novel strain and other members of the family Rhodobacteraceae were below 96.6 %. The isoprenoid quinone was Q-10. The major fatty acids were C18 : 1ω7c, C16 : 0, summed feature 3 (C16 : 0 ω7c and/or C16 : 0 ω6c) and C12 : 0 3-OH. The polar lipids consisted of diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, an unidentified aminolipid, an unidentified phospholipid and an unidentified lipid. The G+C content of the DNA was 63.2 mol% (draft genome). DNA-DNA relatedness value between the novel strain and the type strain of Marimonas arenosa was 12.7±9.0 %. On the basis of data from phenotypic, chemotaxonomic and DNA-DNA hybridization studies together with phylogenetic analyses, strain GH1-19T (=KCTC 62376T=DSM 106292T) represents a novel species of the genus Marimonas, for which the name Marimonas lutisalis sp. nov. is proposed, with the emended description of the genus Marimonas.

Kangsaoukella pontilimi gen. nov., sp. nov., a new member of the family Rhodobacteraceae isolated from a tidal mudflat.

A strictly aerobic, Gram-stain-negative, non-motile, ovoid- and rod-shaped bacterium, designated strain GH1-50T, was isolated from a tidal mudflat sample collected from Dongmak seashore on Gangwha Island, Republic of Korea. The organism showed growth at 20-40 °C (optimum, 30 °C), pH 7-8 (optimum, pH 7) and 2-6  % (w/v) NaCl (optimum, 5 %). The pufLM genes were present but bacteriochlorophyll a was not detected. The major isoprenoid quinone was Q-10. The polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, an unidentified aminolipid and five unidentified lipids. The predominant cellular fatty acids were C18 : 1 ω7c, C18 : 1 ω7c 11-methyl and C18 : 0. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that the isolate belonged to the family Rhodobacteraceae and was loosely associated with members of the recognized genera. The closest relative was the type strain of Pseudoruegeria marinistellae (96.8 % similarity) followed by Boseongicola aestuarii (96.4 %). Other members of the family shared 16S rRNA gene similarity values below 96.0 % to the novel isolate. The DNA G+C content calculated from the draft genome sequence was 64.0 %. The average amino acid identity, average nucleotide identity and digital DNA-DNA hybridization values between genome sequences of strain GH1-50T and all the type strains of the recognized taxa compared were <70.0, <84.1 and <20.5 %, respectively. Based on data obtained by a polyphasic approach, strain GH1-50T (=KCTC 72224T=NBRC 113929T) represents a novel species of a new genus in the family Rhodobacteraceae, for which the name Kangsaoukella pontilimi gen. nov., sp. nov. is proposed.

Seongchinamella unica gen. nov., sp. nov., isolated from a tidal mudflat of beach, and transfer of Halioglobus sediminis to Seongchinamella sediminis comb. nov. and Halioglobus lutimaris to Pseudohalioglobus gen. nov. as Pseudohalioglobus lutimaris comb. nov.

A Gram-reaction-negative, motile by gliding, rod-shaped bacterium, designated strain GH4-78T, was isolated from the tidal mudflat of a beach in the Republic of Korea. Cells were aerobic, catalase-positive, oxidase-negative and produced cream-coloured colonies. Q-8 was the only isoprenoid quinone. The major fatty acids were summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) and C16 : 0. The major polar lipids are phosphatidylethanolamine and phosphatidylglycerol. Results of phylogenetic analyses based on 16S rRNA gene sequences revealed that strain GH4-78T formed a distinct lineage with Halioglobus sediminis (98.2 % sequence similarity). The DNA G+C content was 59.9 mol%. The average nucleotide identity value with the closest relative was 82.90 %. On the basis of the results from phenotypic, chemotaxonomic, phylogenetic and phylogenomic analyses, strain GH4-78T (=KCTC 62383T=DSM 106349T) represents a novel species of a new genus in the family Halieaceae, for which the name Seongchinamella unica gen. nov., sp. nov. is proposed. Moreover, the transfers of Halioglobus sediminis Han et al. 2019 to Seongchinamella sediminis comb. nov. and Halioglobus lutimaris Shi et al. 2018 to Pseudohalioglobus gen. nov. as Pseudohalioglobus lutimaris comb. nov. are also proposed, with the emended description of the genus Halioglobus.

Sneathiella limimaris sp. nov., a marine alphaproteobacterium isolated from a tidal mudflat and emended description of the genus Sneathiella.

A novel marine bacterium, designated strain GH1-24T, was isolated from a tidal mudflat sample collected at Gangwha Island, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequence comparison exhibited that the novel isolate was most closely related to Sneathiella and formed a tight cluster with Sneathiella glossodoripedis JCM 23214T with 98.1 % sequence similarity. The 16S rRNA gene sequence similarities to other Sneathiella species were low: Sneathiella chinensis LMG 23452T (96.1 %) and Sneathiellachungangensis CAU 1294T (95.8 %). Cells of the organism were Gram-reaction-negative, strictly aerobic, catalase- and oxidase-positive, motile rods and showed growth at 0.5-6 % NaCl, 20-42 °C and pH 6.0-8.0. The G+C content of the DNA was 54.9 mol%. The major isoprenoid quinone was Q-10. The major cellular fatty acids were C18 : 1ω7c, C16 : 0 and C19 : 0cyclo ω8c. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol and an unidentified aminophospholipid. The results of phenotypic and phylogenetic analyses and DNA-DNA relatedness studies suggest that the isolate can be a member of a novel species of the genus Sneathiella, for which the name Sneathiellalimimaris sp. nov. is proposed. The type strain is GH1-24T (=KCTC 52846T=NBRC 113276T).

Altererythrobacter lutipelagi sp. nov., isolated from a tidal mudflat, and emended description of the genus Altererythrobacter.

A marine proteobacterium, designated strain GH1-16T, was isolated from a sample of tidal mudflat collected at the seashore of Gangwha Island, Republic of Korea and the taxonomic status was examined by a polyphasic approach. The isolate was Gram-reaction-negative, strictly aerobic, catalase- and oxidase-positive, non-motile, short-rod-shaped and produced yellow-coloured colonies. An absolute requirement for Na+ was observed. The major respiratory quinone was ubiquinone-10. The major polar lipids consisted of phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and sphingoglycolipid. The dominant cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C17 : 1ω6c. The DNA G+C content was 60.6 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain GH1-16T was closely related to members of the genus Altererythrobacter. The closest relative was Altererythrobacter marensis MSW-14T (97.3 % sequence similarity) followed by Altererythrobacter aquaemixtae JSSK-8T (96.8 %) and Altererythrobacter epoxidivorans JCS350T (96.7 %). The DNA relatedness of strain GH1-16T against its closest relative was 21.8-25.0 %. On the basis of data obtained by a polyphasic taxonomic approach, strain GH1-16T (=KCTC 52845T=NBRC 113275T) is considered to represent a novel species of the genus Altererythrobacter, for which the name Altererythrobacter lutipelagi sp. nov. is proposed.

Lutibaculum pontilimi sp. nov., isolated from a tidal mudflat and emended description of the genus Lutibaculum.

A novel Gram-reaction-negative bacterium, designated strain GH1-34T, was isolated from a sample of tidal mudflat collected at the seashore of Gangwha Island, Republic of Korea. Cells of the bacterium were strictly aerobic, catalase- and oxidase-positive, motile by means of a polar flagellum and rod shaped. It was found to grow at 0-5 % (w/v) NaCl, 20-45 °C and pH 6-10. The major isoprenoid quinone was Q-10. The polar lipids were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, an unidentified aminolipid and an unidentified glycolipid. The predominant fatty acids were C18 : 1ω7c and C19 : 0cyclo ω8c. The G+C content of the DNA was 70.9 mol%. Comparative 16S rRNA gene sequence analysis revealed that strain GH1-34T formed a tight cluster with the type strain of Lutibaculum baratangense with 98.3 % sequence similarity; levels of the 16S rRNA gene sequence similarity between the novel strain and other representatives of the order 'Rhizobiales' were <95.0 %. DNA-DNA relatedness between the organism and L. baratangense KCTC 22669T was 33 %, Based on the results of phenotypic analysis and DNA-DNA hybridization experiments, strain GH1-34T (=KCTC 52847T=NBRC 113277T) represents a novel species of the genus Lutibaculum, for which the name Lutibaculum pontilimi sp. nov. is proposed.

Maribius pontilimi sp. nov., isolated from a tidal mudflat.

A novel marine Gram-negative bacterium, designated strain GH1-23T, was isolated from a tidal mudflat sample collected at Dongmak seashore on Gangwha Island, Republic of Korea and its taxonomic position was determined through a polyphasic investigation. The bacterium was strictly aerobic, chemoheterotrophic, catalase- and oxidase-positive, consisted of non-motile rods and grew optimally at 30 °C, pH 7 and 1 % NaCl. The predominant cellular fatty acids were C18 : 1ω7c and cyclo-C19 : 0ω8c. The major isoprenoid quinone was Q-10. The major polar lipids were phosphatidylglycerol, a phosphoglycolipid and an aminolipid. Comparative 16S rRNA gene sequence analysis revealed that the isolate was closely related to members of the genus Maribius. The highest 16S rRNA gene sequence similarity was found to be 97.5 % to Maribius salinus followed by 97.4 % to Maribius pelagius; levels of 16S rRNA gene sequence similarity between the novel strain and other representatives of family Rhodobacteraceae were <95.5 %. The DNA G+C content was 66.7 mol % and DNA-DNA relatedness values with the type strains of species of the genus Maribius were 33-39 %. Based on combined data from a polyphasic investigation, strain GH1-23T (=KCTC 52957T=DSM 104950T) represents a novel species of the genus Maribius, for which the name Maribius pontilimi sp. nov. is proposed.

Cystargamides C and D, New Cyclic Lipopeptides From a Tidal Mudflat-Derived Streptomyces sp. JMS132.

Cystargamides C and D (2 and 3) were isolated from a marine actinomycete strain collected at Beolgyo, South Korea. The planar structures of the cystargamides were elucidated by 1/2D NMR, UV, and MS spectroscopic analyses. The absolute configurations of 2 and 3 were determined based on ROESY correlations and the advanced Marfey's methods. The structures of the compounds were elucidated as new lipodepsipeptides bearing six amino acids with an epoxy fatty acid side chain. For the first time, the nonribosomal peptide synthetase biosynthetic pathway of the cystargamides has been proposed using whole genome sequence analysis. The cystargamides displayed antioxidant effect in the DPPH and ABTS assay. The discovery of new cyclic lipopeptides, cystargamides C and D, from a tidal mudflat-derived Streptomyces sp. supported that marine bacteria have potential as source of bioactive natural products.

Martelella lutilitoris sp. nov., isolated from a tidal mudflat.

A novel, Gram-stain-negative marine bacterium, designated GH2-6T, was isolated from a rhizosphere mudflat of a halophyte (Carex scabrifolia) collected in Gangwha Island, the Republic of Korea. The cells of the organism were strictly aerobic, oxidase- and catalase-positive, non-flagellated rods. Growth occurred at 20-45°C, pH 5-10, and 0.5-9 (w/v) NaCl. The requirement of Na+ for growth (0.5-3%) was observed. The major respiratory quinone was Q-10. The major polar lipids were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, an aminolipid and a glycolipid. The predominant fatty acids were C18:1ω7c, C18:0, C16:0, C19:0 cyclo ω8c, C18:1ω7c 11-methyl and summed feature 2 (C14:0 3-OH and/or C16:1 iso I). The genome size was 4.45 Mb and the G+C content of the genomic DNA was 61.9 mol%. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain GH2-6T belonged to genus Martelella and formed a tight cluster with M. radicis BM5-7T and M. endophytica YC6887T. Levels of 16S rRNA gene sequence similarity between the novel isolate and members of the genus were 99.3-95.5%, but strain GH2-6T possessed an extended loop (49 nucleotides in length) between positions 187 and 213 of the 16S rRNA gene sequence (E. coli numbering). DDH values in vitro between the novel isolate and the closest relatives were 23.2±12.8-46.3±5.2%. On the basis of polyphasic data presented in this study, the type strain GH2-6T (= KACC 19403T = KCTC 62125T = NBRC 113212T) represents a novel species of the genus Martelella for which the name Martelella lutilitoris sp. nov. is proposed.