Abstract: In this paper, the medium composition and process conditions of polysaccharides produced by liquid fermentation of Monascus were optimized, and the extraction, purification, antioxidation and antibacterial activities of liquid fermentation polysaccharides from Monascus were studied. Under the liquid fermentation of a medium consisting of 40 mg/mL rice flour, 10 mg/mL soybean powder, 0.15 mg/mL KCl, 0.15 mg/mL KH₂PO₄, 0.15 mg/mL NaCl, optimized by single factor experiment,the fermentation process conditions are as follows: the fermentation medium maintains an initial pH value of 32 ℃ and a rotational speed of 180 r/min. Under this condition, the mass concentration of polysaccharides in the liquid fermentation of Monascus shake flask reached 142.3 mg/mL, which was about 1.3 times that before optimization. The preliminary detection of the antioxidant activity of the extracted Monascus polysaccharides showed that the Monascus exopolysaccharide scavenged DPPH free radicals better, and the ability to scavenge hydroxyl radicals was weak. Moreover, Monascus polysaccharide had a certain antibacterial effect on Escherichia coli and Aerobacteria, but had no antibacterial activity against Bacillus subtilis.

Key words: Monascus extracellular polysaccharide, condition optimization, polysaccharide extraction, antioxidant, bacteriostatic