Vulcaniibacterium gelatinicum sp. nov., a moderately thermophilic bacterium isolated from a hot spring.

The present study aimed to determine the taxonomic positions of strains designated R-5-52-3T, R-5-33-5-1-2, R-5-48-2 and R-5-51-4 isolated from hot spring water samples. Cells of these strains were Gram-stain-negative, non-motile and rod-shaped. The strains shared highest 16S rRNA gene sequence similarity with Vulcaniibacterium thermophilum KCTC 32020T (95.1%). Growth occurred at 28-55 °C, at pH 6-8 and with up to 3 % (w/v) NaCl. DNA fingerprinting, biochemical, phylogenetic and 16S rRNA gene sequence analyses suggested that R-5-52-3T, R-5-33-5-1-2, R-5-48-2 and R-5-51-4 were different strains but belonged to the same species. Hence, R-5-52-3T was chosen for further analysis and R-5-33-5-1-2, R-5-48-2 and R-5-51-4 were considered as additional strains of this species. R-5-52-3T possessed Q-8 as the only quinone and iso-C15:0, iso-C11:0, C16 : 0 and iso-C17 : 0 as major fatty acids. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified polar lipids and two unidentified phospholipids. The genomic G+C content was 71.6 mol%. Heat shock proteins (e.g. Hsp20, GroEL, DnaK and Clp ATPases) were noted in the R-5-52-3T genome, which could suggest its protection in the hot spring environment. Pan-genome analysis showed the number of singleton gene clusters among Vulcaniibacterium members varied. Average nucleotide identity (ANI) values between R-5-52-3T, Vulcaniibacterium tengchongense YIM 77520T and V. thermophilum KCTC 32020T were 80.1-85.8 %, which were below the cut-off level (95-96 %) recommended as the ANI criterion for interspecies identity. Thus, based on the above results, strain R-5-52-3T represents a novel species of the genus Vulcaniibacterium, for which the name Vulcaniibacterium gelatinicum sp. nov. is proposed. The type strain is R-5-52-3T (=KCTC 72061T=CGMCC 1.16678T).

A new cytochalasin from endophytic Phomopsis sp. IFB-E060.

AIM: To study the chemical constituents of the solid culture of the endophyte Phomopsis sp. IFB-E060 in Vatica mangachapoi. METHOD: Isolation and purification were performed through silica gel column chromatography, gel filtration over Sephadex LH-20, ODS column chromatography, and HPLC. Structures of the isolated compounds were elucidated by a combination of spectroscopic analyses (UV, CD, IR, MS, 1D, and 2D NMR). The cytotoxicity of the isolates was evaluated in vitro by the MTT method against the human hepatocarcinoma cell line SMMC-7721. RESULTS: Five compounds were isolated from the solid culture of the endophyte Phomopsis sp. IFB-E060 and their structures were identified as 18-methoxy cytochalasin J (1), cytochalasin H (2), (22E, 24S)-cerevisterol (3), ergosterol (4), and nicotinic acid (5). Compound 1 had an inhibition rate of 24.4% at 10 µg·mL(-1) and 2 had an IC50 value of 15.0 µg·mL(-1), while a positive control 5-fluorouracil had an inhibition rate of 28.7% at 10 µg·mL(-1). CONCLUSION: 18-Methoxy cytochalasin J (1), produced by endophytic Phomopsis sp. IFB-E060, is a new cytochalasin with weak cytotoxicity to the human hepatocarcinoma cell line SMMC-7721.