Polysaccharide produced by Bacillus subtilis using burdock oligofructose as carbon source

In this study, a polysaccharide, BP, was produced by Bacillus subtilis using burdock oligofructose as a carbon source. The polysaccharide BP was isolated from burdock fermented through B. subtilis by hot water extraction, ethanol precipitation, anion exchange and gel filtration chromatography. The molecular weight of BP was determined to be 1.533 × 10⁷ g/mol, and is composed of mannose, rhamnose, glucose, galactose, and arabinose in the ratio of 1:0.12:17.16:0.69:1.10. Furthermore, BP is made up of a backbone structure of (1→6)-linked α-d-glucopyranosyl residues substituted at the O-3 position with α-d-glucopyranosyl branches. In vitro, BP inhibited A549 cell proliferation and increased reactive oxygen species production, thus, promoting the apoptosis of cells. Moreover, BP up-regulated the expression of caspase-3 and the corresponding protein, indicating that it activates the caspase-3 pathway. These findings suggest that the potential of BP as a supplement or drug to treat cancer.