Effect of metal ions on the growth and metabolites production of Ganoderma lucidum in submerged culture
The effects of several metal ions on the cell growth, production of polysaccharides by Ganoderma lucidum in submerged fermentation were studied. The results showed that 50 ppm Se2+ and 25 ppm Se2+ was identified to be the most favorable for biomass (11.103 ± 0.6 g/l ) and polysaccharide production (IPS and EPS was 183 ± 10.2 and 248 ± 5.5 mg/l, respectively); 100 ppm of Fe2+ and 50 ppm of Zn2+ were suitable for growth (the biomass was 8.23 ± 0.67 and 8.01 ± 0.29 g/l, respectively) and under the concentration of 50 ppm of Zn2+ and Fe2+, the production of polysaccharide was up to the most (EPS content: 263±4 and 254.3±8.0 mg/l; IPS content : 170±0.8 and 174±5 mg/l); Mg2+ had no obvious effect on biomass and polysaccharide production; Cr2+ was poisonous to the cell under the test concentration. The combination (FeSO4, 50 ppm; NaSeSO3, 25 ppm; ZnSO4, 75 ppm) by A 9 ×3 replicates (27) experiments of L9 (34) orthogonal projects was tested optimal for the cell growth and polysaccharides production. Biomass, EPS and IPS production reached their good value of 14.7 ± 0.5 g/l, 369 ± 6 mg/l and 239 ± 4 mg/g, respectively under the combination, which were higher 130.7, 50 and 50%, respectively than in the basal fermentation medium without metal ions. The validation experiment showed the experimental values agreed with the predicted values well (error <1%).
Key words: Ganoderma lucidum, metal ions, biomass, polysaccharide, orthogonal projects.