利用扁桃斑鸠菊叶发酵高产粗毛纤孔菌胞外多糖的条件优化及其抗氧化活性研究

粗毛纤孔菌胞外多糖是粗毛纤孔菌液体发酵的重要活性代谢产物,但采用常规的发酵方法,粗毛纤孔菌胞外多糖的产量较低。为更好地获取粗毛纤孔菌胞外多糖,本文采用双向液体发酵的方法,通过向发酵培养基中添加适量的扁桃斑鸠菊叶粉末,来提高粗毛纤孔菌胞外多糖的产量,并对优化得到的胞外多糖抗氧化活性进行了研究。以发酵液中胞外多糖含量为指标,采用单因素实验和正交实验优化发酵条件;采用红外光谱对胞外多糖的结构特征进行分析;通过测定胞外多糖对ABTS、DPPH和羟基自由基的清除率来了解其抗氧化活性。结果表明,最优发酵条件为：扁桃斑鸠菊叶粉末添加量0.5g/L、发酵时间10d、pH 6.5、接种量5.0mL,在此条件下,粗毛纤孔菌胞外多糖的产量达到(2.34±0.25)mg/mL,与未添加扁桃斑鸠菊叶的空白组相比,其胞外多糖产量提高了约216.22%;红外分析与抗氧化活性实验结果表明,添加扁桃斑鸠菊叶后的胞外多糖与未添加扁桃斑鸠菊叶的胞外多糖红外主要吸收峰一致,并且对ABTS、DPPH以及羟基自由基清除能力相近。本研究结果表明扁桃斑鸠菊叶能够有效地提高粗毛纤孔菌胞外多糖的产量,为其他珍稀食药用菌胞外多糖的高效生产提供了新思路。

Optimization on fermentation conditions for high production of Inonotus hispidus exopolysaccharides using Vernonia amygdalina dried leaf powder as additive and analyses on antioxidant activities of the polysaccharide product

Exopolysaccharide (EPS) is an important kind of active metabolite of Inonotus hispidus in liquid fermentation. Usually, the yield of Inonotus hispidus EPS is low obtained from conventional fermentation. In this study, bi-directional liquid fermentation was adopted to promote the Inonotus hispidus EPS production by adding Vernonia amygdalina leaf powder to the fermentation medium. Using the content of EPS in fermentation broth as main index, the fermentation conditions were optimized through single factor and orthogonal test, and infrared spectroscopy was used to analyze the structural features of EPS. ABTS, DPPH, hydroxyl radical scavenging rates were measured to detect the antioxidant activity of EPS. The optimum fermentation conditions were as follows: addition of V. amygdalina dried leaf powder of 0.5g/L, fermentation duration of 10d, initial pH of 6.5, inoculum size of 5.0mL. Under such a condition, the yield of Inonotus hispidus EPS can reach (2.34±0.25)mg/mL, increased by 216.22% as compared with the experimental control without addition of the leaf powder. Infrared analysis and antioxidant activity tests indicated the principal absorption peaks of the EPS product accorded with those of experimental control, and the ability of the EPS product to scavenge ABTS, DPPH and hydroxyl radicals was similar to that of control. The result of this research suggests that V. amygdalina leaf can enhance the production of Inonotus hispidus EPS effectively.