Optimization of culture parameters affecting polysaccharide production by a strain of Boletus edulis grown in submerged culture.

The effects of selected culture parameters on polysaccharide production by a strain of Boletus edulis are described.Optimal conditions for small-scale polysaccharide production in submerged flask cultures were as follows:a fermentation medium consisting of 10% potato,2% sucrose,0.6% peptone,0.10% ZnSO4·7H2O,0.2% CaCO3,0.3% KH2PO4 and 0.2% MgSO4·7H2O,pH 5.0～5.4,120 r/min shaking speed,temperature 25～28 ℃,40% medium loading ratio,10 glass beads per flask,and a 5-day incubation period.Under these conditions,polysaccharide production reached a peak of 3.161 g/L.In 10-L fermenter cultures using the same medium,pH,temperature,a 50% medium loading ratio,a similar stirrer speed,and an aeration rate of 0.8 vvm,highest polysaccharide yields were obtained after four days.