Jia Xuewei, Qu Lili, Panpan Ran, Liu Shuai, Wu Yan, Xu Chunping
College of Food and Biological Engineering, Zhengzhou University of Light Industry, Zhengzhou, Henan, China; Collaborative Innovation Center of Food Production and Safety, Zhengzhou, Henan, China.
College of Food and Biological Engineering, Zhengzhou University of Light Industry, Zhengzhou, Henan, China.
Int J Med Mushrooms. 2018;20(4):311-320. doi: 10.1615/IntJMedMushrooms.2018025808.
In this investigation we developed an optimal fermentation medium to produce an exopolysaccharide (EPS) with antioxidant activity from Rigidoporus microporus. Lactose and tryptone were chosen as the optimal carbon and nitrogen sources, respectively, for EPS production, with a 6-day cultivation cycle. After removing proteins through the use of the Sevag method, one EPS fraction was purified from the culture filtrates by gel filtration chromatography on a Sepharose CL-6B column. The preliminary chemical structure of the EPS fraction was determined by Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, and nuclear magnetic resonance. The results indicated that the main structure of the EPS consisted of β-glucopyranose and mannopyranose. Furthermore, conformational parameters such as molecular weight (Mw), intrinsic viscosity ([η]), mean-square radii of gyration (Rg), and hydrodynamic radius (Rh) of the EPS were characterized using a size exclusion chromatography-multiangle light scattering-refractive index viscometry method. It showed that the EPS was a kind of water-soluble polysaccharide with a moderate molecular weight (34.1 × 104) and a flexible, linear random coil chain structure. The antioxidant activity tests suggested that the EPS has great potential application as a natural antioxidant material in foods and medicines.
在本研究中，我们开发了一种优化的发酵培养基，用于从微小硬孔菌中生产具有抗氧化活性的胞外多糖（EPS）。乳糖和胰蛋白胨分别被选为EPS生产的最佳碳源和氮源，培养周期为6天。通过使用Sevag法去除蛋白质后，通过在Sepharose CL-6B柱上进行凝胶过滤色谱从培养滤液中纯化出一个EPS组分。通过傅里叶变换红外光谱、气相色谱 - 质谱和核磁共振确定了EPS组分的初步化学结构。结果表明，EPS的主要结构由β - 吡喃葡萄糖和吡喃甘露糖组成。此外，使用尺寸排阻色谱 - 多角度光散射 - 折光率粘度法对EPS的构象参数如分子量（Mw）、特性粘度（[η]）、均方回转半径（Rg）和流体力学半径（Rh）进行了表征。结果表明，EPS是一种具有中等分子量（34.1×104）且具有柔性、线性无规卷曲链结构的水溶性多糖。抗氧化活性测试表明，EPS作为天然抗氧化材料在食品和药品中具有巨大的潜在应用价值。
