韦兰胶（welan gum）是由鞘氨醇单胞菌（Sphingomonas paucimobilis）分泌的一种可溶性胞外多糖。利用实验室优化筛选的一株韦兰胶产生菌Sphingomonas sp. 511，通过单因素实验，研究了韦兰胶发酵工艺条件，得出韦兰胶适宜的发酵条件为：种龄15 h，接种量10%，装液量80 mL（500 mL 摇瓶），初始pH 8.0，摇床转速300 r/min，培养温度32 ℃，发酵时间72 h，在此实验基础上进行10 L 发酵罐的放大试验，韦兰胶产率为25.76 g/L。

Welan gum is a soluble exopolysaccharide produced by Sphingomonas sp. The fermentation conditions were optimized by single-factor experiments using a welan gum producing strain Sphingomonas sp. 511 screened in our laboratory. The optimal fermentation conditions were as follows: inoculum age 15 h, inoculum volumn 10% (V/V), medium volumetric ratio 16% (V/V), initial pH value 8.0, rotate speed 300 r/min, culture temperature 32 ℃ and fermentation period 72 h. The scale-up test was carried out under these conditions and the concentration of welan gum reached 25.76 g/L.