In: Sydowia 72, (2020): 115-122, ISSN 0082-0598, DOI 10.12905/0380.sydowia72-2020-0115, Published online on April 17, 2020

Bioassay-guided isolation of antibacterial fractions from extracts of submerged-cultured Inonotus obliquus

Lulu Yan & Xiangqun Xu (2020) Bioassay-guided isolation of antibacterial fractions from extracts of submerged-cultured
Inonotus obliquus. – Sydowia 72: 115–122.

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.