Exopolysaccharide production and its antioxidant properties of Armillaria mellea in batch fermentation

• Main Authors: Chih-Wei Hsieh, 謝志偉
• Other Authors: Ming-Yeou Lung
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/86517665068944422832

碩士 === 明新科技大學 === 化學工程研究所 === 98 === Abstract Armillariella mellea is one of the fungi food-medicine mushrooms to tranquilize the central nervous system and to reduce the mice death rate induced by nicotine. It can also treat dizziness, palsy, insomnia, tinnitus, etc.,imultaneously. Many researchers have demonstrated that A. mellea polysaccharides are excellent in anti-tumor and antioxidant activities. In this study, influence of culture aeration rate and temperature, two-stage, four-stage on polysaccharide fermentation from Armillariella mellea by submerged culture and its antioxidant properties were examined. Armillariella mellea culture at different aeration rate ranging from 0.3 vvm to 1.5 vvm by submerged cultures was individually carried out in a 5-L fermentor and to increase production of exopolysaccharide (EPS) by regulating two-stage culture strategy (1.2 vvm → 0.6 vvm). Armillariella mellea culture at different temperature ranging from 13 ℃ to 34 ℃ by submerged cultures was individually carried out in a 5-L fermentor and to increase production of exopolysaccharide (EPS) by regulating two-stage culture strategy (28 ℃→ 22 ℃). The experimental results exhibited that the maximum of mycelia production in stirred-tank bioreactor was 7.16 mgmL-1 at 1.2 vvm. The maximum EPS production was 0.17 mgmL-1 at 0.6 vvm. To improve the biomass and EPS production, the two-stage culture strategy was used. The two-stage aeration rate process (1.2 vvm → 0.6 vvm) demonstrated a high biomass and EPS producttion with 11.43 mgmL-1and 0.27 mgmL-1. The experimental results exhibited that the maximum of mycelia production in stirred-tank bioreactor was 12.61 mgmL-1 at 28℃ . The maximum EPS production was 0.21 mgmL-1 at 22℃. To improve the biomass and EPS production, the two-stage culture strategy was used. The two-stage temperature process (28 ℃ → 22 ℃) demonstrated a high biomass and EPS producttion with16.45 mgmL-1and 0.36 mgmL-1. The four-stage aeration rate culture, including aeration rate process (1.2 vvm → 0.6 vvm) and temperature process( 28 ℃ → 22 ℃) demonstrated a high biomass and EPS production with 21.34 mgmL-1and 0.44 mgmL-1, respectively. In addition, The four-stage fermentation product extracts, exopolysaccharide (EPS) and intracellular polysaccharide (IPS), showed a high antioxidant activity, reducing powers, scavenging effects on 1,1-diphenol-2-picrylhydrazyl radicals (DPPH), chelating effects and scavenging effects on superoxide anion. For reducing owers, the lowest EC50 value of 0.34 mgmL-1 for IPS was achieved from four-stage culture strategy. The lowest EC50 values of 0.06 mgmL-1 were obtained for antioxidant activity of ethanolic extract of mycelia from four-stage culture strategy . The lowest EC50 values for hot water extract of mycelia were 1.43 mgmL-1at four-stage culture strategy for scavenging effects on 1,1-diphenol-2-picrylhydrazyl radicals (DPPH). For chelating effects, the lowest EC50 values of EPS were 0.11 mgmL-1 by four-stage culture. For scavenging effects on superoxide anion, the lowest EC50 values from hot water extracts of mycelia by four-stage culture were 0.03 mgmL-1. In two-stage aeration rate culture strategy, the number molecular weight of EPS and IPS were 2.14×106 Da and 6.13×106 Da, respectively. The two-stage temperature culture strategy, the number molecular weight of IPS and EPS were 5.99×106 Da and 2.16×106 Da, respectively. The number molecular weights of IPS and EPS from the four-stage were 6.61×106 Da and 3.34×106 Da, respectively. In antioxidant properties, the high molecular weight and polysaccharide had better antioxidant activities. The results could provide a reference for future study and antioxidant health-food production of large-scale process.