Bioassay-guided isolation of antibacterial fractions from extracts of submerged-cultured Inonotus obliquus
Lulu Yan & Xiangqun Xu
Sydowia 72: 115-122
Published online on April 17th, 2020
Inonotus obliquus (I. obliquus) is an edible and traditional medicinal mushroom. Levels of some of the bioactive components it contains could possibly be increased under submerged fermentation. In order to identify the antimicrobial activity of submerged- cultured I. obliquus, various fractions of the mixture were prepared and isolated by bioassay-guidance. By means of liquid-liquid extraction, D101 macroporous adsorption resin and silica gel column chromatography, the sub-fraction of D101- Fr.1 from the ethyl acetate extract was found to be the most efficient on Staphylococcus aureus ATCC 6538, while the sub-fraction of SG-Fr.1 isolated via silica gel column chromatography from the ethyl acetate extract showed the best effect on Escherichia coli ATCC 6538. In addition, D101-Fr.1 and SG-Fr.1 could inhibit the initial cell attachment and the preformed biofilm for S. aureus and E. coli. Surprisingly, different fractions from submerged-cultured I. obliquus showed a much longer effect on all the strains compared to ampicillin. This study contributes to investigate the antimicrobial effect of I. obliquus and is significant for seeking natural agents against harmful bacteria instead of antibiotics in the future.
Key words: Inonotus obliquus, submerged fermentation, antimicrobial activity, antibiofilm, bioassay-guided isolation.
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