Abstract Gellan gum is a water-soluble exopolysaccharide, it has applications in the food, pharmaceutical and chemical industries. In this study, a gellan gum producing strain was isolated from rice root, and this strain was identified be the species of Sphingomonas azotifigens. The Plackett-Burman design was applied to investigate the main factors affecting gellan gum production by S. azotifigens GL-1 in a molasses and cheese whey based medium; the medium compositions were optimized by response surface methodology. The optimum cheese whey based medium consisted of cheese whey 68.34 g/L, Na2HPO4 14.58 g/L and KH2PO4 7.66 g/L, and the maximum gellan gum production that using this medium was 33.75 ± 1.55 g/L. 14.75 ± 0.65 g/L gellan gum was obtained with an optimized molasses medium, which consisted of molasses 50 g/L, Na2HPO4 9.71 g/L and KH2PO4 5.92 g/L. The molecular weight of gellan gum obtained from two medias were 1.06 × 106 and 0.89 × 106 Da, respectively. The cheese whey-derived gellan gum showed a higher rhamnose, lower glucuronic acid and higher glycerate content compared to the molasses-derived gellan gum. S. azotifigens GL-1 has a high gellan gum production capacity in a cheap medium suggesting it has great potential as an industrial gellan gum producer.

中文翻译：

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在基于奶酪乳清和糖蜜的培养基中通过新分离的 Sphingomonas azotifigens GL-1 改进结冷胶生产

摘要 结冷胶是一种水溶性胞外多糖，在食品、医药和化工等行业都有应用。本研究从水稻根中分离出一株产结冷胶的菌株，该菌株被鉴定为Sphingomonas azotifigens。Plackett-Burman 设计用于研究影响 S. azotifigens GL-1 在糖蜜和奶酪乳清培养基中生产结冷胶的主要因素；通过响应面法优化培养基成分。最佳奶酪乳清基培养基由奶酪乳清 68.34 g/L、Na2HPO4 14.58 g/L 和 KH2PO4 7.66 g/L 组成，使用该培养基的最大结冷胶产量为 33.75 ± 1.55 g/L。使用由糖蜜 50 g/L、Na2HPO4 9.71 g/L 和 KH2PO4 5 组成的优化糖蜜培养基获得 14.75 ± 0.65 g/L 结冷胶。92 克/升。从两种介质中获得的结冷胶的分子量分别为 1.06 × 106 和 0.89 × 106 Da。与糖蜜来源的结冷胶相比，干酪乳清来源的结冷胶显示出更高的鼠李糖、更低的葡萄糖醛酸和更高的甘油酸含量。S. azotifigens GL-1 在廉价培养基中具有很高的结冷胶生产能力，表明它作为工业结冷胶生产商具有巨大潜力。