RESUMEN
Objective The anti-UV-B radiation mechanism of UV-B tolerance strain KFS-9 was studied from the profile of metabolites.Methods The compounds were separated by column chromatography and their structures were elucidated based on GC-MS,LC-TOF-MS,EI-MS and NMR analyses.Results Three unsaturated fatty acids(identified as 9-hexadecenoic acid,9,12-octadecadienoic acid and 11-octadecenoic acid) and 1,2-benzenedicarboxylic acid able to absorb ultraviolet were isolated from the petroleum ether extract of the fermentation liquid of Pantoea agglomerans KFS-9.Fraction(Ⅱ) was isolated from the ethyl acetate extract and was composed of 2,3-butanediol and a series of high unsaturated aroma compounds.Fraction(Ⅱ) had a wide absorption peak,and it could protect E.coli from UV-B damage in some sense.Conclusion Strain KFS-9 produced metabolites that were able to absorb UV to build a natural barrier and so improved the tolerance to UV radiation.The UV-B radiation protection test to the E.coli also showed fraction(Ⅱ) was not the only protector,and there definitely existedother materials and mechanism to protect the strain.