Pedobacter riviphilus sp. nov., isolated from stream sediment.

A Gram-stain-negative, aerobic, motile by gliding, rod-shaped and pink-coloured bacterium, designated strain SW-16T, was isolated from the sediment of small stream in the Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain SW-16T formed a lineage within the genus Pedobacter of the family Sphingobacteriaceae. Phylogenetic analysis also showed that strain SW-16T was most closely related to Pedobacter soli 15-51T (98.0% 16S rRNA gene sequence similarity), Pedobacter humicola R135T (97.5%), Pedobacter suwonensis 15-52T (97.4%), Pedobacter sandarakinus DS-27T (97.0%) and Pedobacter kyungheensis THG-T17T (97.0%). Growth was observed at 10-37 °C (optimum at 30 °C), pH 6-8 (optimum at pH 7) and with 0-2.0 % NaCl (optimum at 0%). The major fatty acids of the bacterial strain were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1 ω7c). The predominant respiratory quinone was menaquinone-7 and the major polar lipids were phosphatidylethanolamine, two unidentified amino lipids, one unidentified phospholipid and three unidentified lipids. The genome size of strain SW-16T was 5.8 Mbp and the G+C content was 38.5 mol%. Based on the results of phenotypic, genomic and phylogenetic analyses, strain SW-16T represents a novel species of the genus Pedobacter, for which the name Pedobacter riviphilus sp. nov. is proposed. The type strain is SW-16T (=KEMB 1602-396T=KCTC 82079T=JCM 34181T).

Collagenase and Tyrosinase Inhibitory Compounds from Fish Gut Bacteria Ruegeria atlantica and Pseudoalteromonas neustonica.

Ruegeria atlantica and Pseudoalteromonas neustonica are fish gut bacteria that have been isolated from the guts of Pagrus major and Acanthopagrus schlegelii, respectively. A total of 22 compounds (1-22) were isolated from these two bacteria; 16 compounds (1-16) from R. atalantica and 6 compounds (17-22) from P. neustonica. Their chemical structures were elucidated by spectroscopic and spectrometric data analysis and chemical synthesis. Compounds 11 and 13 showed strong collagenase inhibitory activity, with 31.91% and 36.43% at 20 µM, respectively, comparable to or surpassing that of the positive control epigallocatechin gallate (EGCG, 34.66%). Also, compounds 11 and 14 exhibited a mild tyrosinase inhibitory effect of 6.73% and 13.68%, respectively. All of the tested compounds displayed no significant antibacterial activity against Escherichia coli and Bacillus subtilis up to 100 µM. The collagenase- and tyrosinase-inhibitory compound 11, cyclo(l-Pro-d-Leu), was found to be stable under heat (50 °C) and UV light (254 and 365 nm) for up to 6 days. These results indicate that compound 11 could be developed into a cosmeceutical with antiaging effects.