Bacillus solimangrovi sp. nov., isolated from mangrove soil.

Two novel bacterial strains, GH2-4T and GH2-5, were isolated from mangrove soil near the seashore of Weno island in Chuuk state, Micronesia, and were characterized by a polyphasic approach. The two strains were strictly aerobic, Gram-staining-positive, motile, endospore-forming rods that were catalase- and oxidase-positive. Colonies were circular, convex, stringy and transparent yellowish (GH2-4T) or opaque whitish (GH2-5). The 16S rRNA gene sequences of the two isolates were identical. The most closely related strains in terms of 16S rRNA gene sequence similarity were Bacillus kochii WCC 4582T, B. horneckiae DSM 23495T, B. azotoformans LMG 9581T, B. cohnii DSM 6307T and B. halmapalus DSM 8723T (95.6, 95.4, 95.4, 95.2 and 95.2% similarity, respectively). The partial groEL sequence of strain GH2-4T was identical to that of strain GH2-5 and showed <85% similarity to those of the most closely related strains. The isolates grew at pH 5-12 (optimal growth at pH 9), at 10-40 °C (optimum 30-35 °C) and at 0-9% (w/v) NaCl (optimum 1-3% NaCl). The cell-wall peptidoglycan of strains GH2-4T and GH2-5 contained meso-diaminopimelic acid and cell-wall hydrolysates contained ribose as a major sugar. The DNA G+C content was 36 mol%, and DNA-DNA relatedness between the isolates and five related reference strains was 20-24%. Strain GH2-4T exhibited 81% DNA-DNA relatedness with strain GH2-5. The major cellular fatty acids of both strains were iso-C15:0, iso-C16:0, iso-C14:0 and anteiso-C15:0 and the predominant menaquinone was MK-7. On the basis of the evidence from this polyphasic study, strains GH2-4T and GH2-5 (=KCTC 33143=JCM 18995=DSM 27084) represent a novel species of the genus Bacillus, for which the name Bacillus solimangrovi sp. nov. is proposed; the type strain is GH2-4T (=KCTC 33142T=JCM 18994T=DSM 27083T).

Description of Kordiimonas aquimaris sp. nov., isolated from seawater, and emended descriptions of the genus Kordiimonas Kwon et al. 2005 emend. Xu et al. 2011 and of its existing species.

A Gram-negative, aerobic, rod-shaped (0.6-0.9 × 0.7-1.2 µm), motile marine bacterium, designated MEBiC06554(T), was isolated from seawater collected from the East Sea, Korea (also known as the Sea of Japan). 16S rRNA gene sequence analysis revealed that strain MEBiC06554(T) was affiliated to the order Kordiimonadales and showed high similarity to Kordiimonas gwangyangensis GW14-5(T) (95.4 %), but formed a distinct phyletic line. Growth was observed at 10.5-35.0 °C (optimum 20 °C), at pH 5.0-8.0 (optimum pH 7.0) and with 0-13 % (w/v) NaCl (optimum 3.0-3.5 %). The predominant cellular fatty acids were iso-C(15 : 0) (14.9 %), iso-C(17 : 1)ω9c (44.6 %), iso-C(17 : 0) (6.3 %) and summed feature 3 (comprising iso-C(15 : 0) 2-OH and/or C(16 : 1)ω7c; 13.9 %). The DNA G+C content was 50.3 mol%. The major respiratory quinone was Q-10. Phosphatidylethanolamine, two unidentified glycolipids, six unidentified aminolipids, three unidentified lipids and one unidentified aminophospholipid were detected as major polar lipids. On the basis of the data from our polyphasic taxonomic study, strain MEBiC06554(T) should be classified within a novel species of the genus Kordiimonas, as Kordiimonas aquimaris sp. nov. The type strain is MEBiC06554(T) (= KCCM 42940(T) = JCM 16665(T)). Emended descriptions of the genus Kordiimonas and of its species Kordiimonas gwangyangensis and Kordiimonas lacus are also proposed.

Exosomes from differentiating human skeletal muscle cells trigger myogenesis of stem cells and provide biochemical cues for skeletal muscle regeneration.

Exosomes released from skeletal muscle cells play important roles in myogenesis and muscle development via the transfer of specific signal molecules. In this study, we investigated whether exosomes secreted during myotube differentiation from human skeletal myoblasts (HSkM) could induce a cellular response from human adipose-derived stem cells (HASCs) and enhance muscle regeneration in a muscle laceration mouse model. The exosomes contained various signal molecules including myogenic growth factors related to muscle development, such as insulin-like growth factors (IGFs), hepatocyte growth factor (HGF), fibroblast growth factor-2 (FGF2), and platelet-derived growth factor-AA (PDGF-AA). Interestingly, exosome-treated HASCs fused with neighboring cells at early time points and exhibited a myotube-like phenotype with increased expression of myogenic proteins (myosin heavy chain and desmin). On day 21, mRNAs of terminal myogenic genes were also up-regulated in exosome-treated HASCs. Moreover, in vivo studies demonstrated that exosomes from differentiating HSkM reduced the fibrotic area and increased the number of regenerated myofibers in the injury site, resulting in significant improvement of skeletal muscle regeneration. Our findings suggest that exosomes act as a biochemical cue directing stem cell differentiation and provide a cell-free therapeutic approach for muscle regeneration.