Isolation Of UV-B Tolerance Strain Pantoea Agglomerans KFS-9 And Study On Its Radioprotective Mechanism

One UV-B tolerance strain that its extro cellular metabolites can protect it from UV-B irradiation is isolated using the two-step isolation method. 263 Strains are isolated from the mangrove forest marine environment in Shenzhen after repeating enrichment and selection. 5 Strains with high UV-B tolerance are selected from the 263 strains. After selected according to the protection of metabolites against UV-B irradiation, strain KFS-9 is selected as the aim strain. The isolate is identified as Pantoea agglomerans by 16S rRNA gene sequence analysis and conventional identification method, and its accession number in Genbank is DQ350072. A mutant strain KFS-98 that lack of carotenoids gene is obtained, and its tolerance to UV-B irradiation is no obvious change vs. wild-type strain. That indicates that carotenoids have no active contribution to the tolerance of cells against UV-B.In order to study the contribution of small molecular metabolites on the anti-ultraviolet ability, the component and property of UV-B absorbing metabolites from Pantoea agglomerans are studied. From the cell free supernatant of cultures, the extro cellular metabolites with UV absorbing ability are extracted and separated. Their components and structures are analyzed by LC-TOP-MS, GC-MS, 1H NMR, 13C NMR. A series of high unsaturated aromatic pigments dissolved in 2,3-butanediol (BAPs) are obtained from the extro cellular metabolites of strain Pantoea agglomerans KFS-9, which effectively absorb UV irradiation range from 290~340 nm, and have high light stability.The exopolysaccharides from Pantoea agglomerans (PAEPS) is obtained and its basis characteristics are studied elementarily. The suitable procedure for extraction...