稻绿核菌胞外多糖抗氧化活性和培养基优化

Antioxidant Activity of Exopolysaccharide from Villosiclava virens and Medium Optimization for Exopolysaccharide Production

采用Fe3+还原能力和·OH清除能力为检测指标对稻绿核菌(Villosiclava virens)UV-2菌丝水提多糖(WPS)、菌丝碱提多糖(SPS)和胞外多糖(EPS)的抗氧化活性进行了评价,EPS表现出较好的抗氧化活性。为了有效提高发酵培养中EPS的得率,通过Plackett-Burman设计,筛选出培养基中影响EPS生产的主效因子为葡萄糖和蛋白胨。通过单因素实验,确定中心组合设计(CCD)中葡萄糖和蛋白胨浓度的取值范围分别为70~90g/L和10~20 g/L。采用CCD和响应面分析(RSM)优化了对稻绿核菌EPS得率具有显著影响的葡萄糖和蛋白胨的浓度,建立了EPS得率与这两个变量之间的二次回归模型。通过求解该模型EPS得率最大时对应变量的取值,当培养基中葡萄糖浓度为84.08 g/L,蛋白胨浓度为14.11 g/L时,EPS得率达到最大值,为881.40 mg/L。对该优化条件进行实验验证,得到EPS得率为917.80 mg/L,是优化前(87.00 mg/L)的10.55倍。研究结果为今后培养稻绿核菌大规模生产胞外多糖及其开发与应用提供了依据。

The in vitro antioxidant activities of water-extracted mycelial pelysaccharide （ WIS）, sodium hydroxide-extrac- ted mycelial polysaccharidc （SPS） and exopolysaccharide （EPS） from rice false smut pathogen Villosiclava virens UV-2 were evaluated using Fe3 ＋ reducing activity and OH radical scavenging activity assays. EPS exhibited the strongest an- tioxidant activity among the polysaeeharides. In order to increase EPS yield in fermentation culture of V. virens,the main effective factors on EPS production,namely concentrations of glucose and peptone,in fermentation culture were screened by Plackett-Burman experimental matrix. The optimal concentration ranges of glucose and peptone were respectively de- termined as 70-90 g/L and 10-20 g/L by the single-factor experiments. Both the central composite design and response surface methodology were employed to optimize the tested variables （concentrations of glucose and peptone） and to es- tablish a second-order polynomial regression equation between EPS yield and the variables. When the cor^centrations of glucose and peptone in medium were at 84.08 g/L and 14.11 g/L,respectively,the EPS yield reached the maximum （881.40 mg/L）. Verification experiment confirmed the validity with the actual EPS yield as 917.80 mg/L, which was 10.55-fold in comparison with that （87.00 mg,/L） in the original basal medium. The results prodded supporting data for EPS production in large scale and also speeded up the application of the fungus V. virens.