Production of Xanthan Gum and Its Oligosaccharides by Degrading Polysaccharide Coating Effects Through Supplementation of Glucanase

ABSTRACT As xanthan gum (XG) accumulates within the fermentation system, the encapsulated bacterial cells and the high‐viscosity environment of the culture medium progressively impede carbon transfer to the cells. This carbon transfer limitation consequently reduces the XG biosynthesis rate. This study investigated coupled fermentation, effectively mitigating the encapsulation effect of polysaccharides by supplementing a controlled amount of glucanase to synthesize XG and xanthan gum oligosaccharides (XGOS). XG production peaked at 4% glucanase addition. Electron microscopy revealed that this effectively mitigated the polysaccharide encapsulation effect. In a 7 L fermenter, after 108 h of fermentation, the XG yield in the batch supplemented with 4% glucanase reached 29.45 g·L −1 , representing a 36.1% increase compared to the control group (XG yield of 21.65 g·L −1 ). Glycerol residue was measured at 3.87 g·L −1 , while the glycerol consumption in the group without glucanase addition was 8.695 g·L −1 . By adjusting glucanase concentration (6%–18%), a coupled fermentation system for XGOS production was established. At 14% glucanase addition, XGOS yield reached 1.675 g·L −1 , with a molecular weight of 901 Da. Scaled‐up fermentation in a 7 L bioreactor yielded 4.46 g·L −1 of XGOS after 108 h, representing a 1.65‐fold increase compared to the 1.68 g·L −1 obtained in the shake flask experiment. This study presents an innovative approach to effectively mitigate the impact of XG‐coated cells. By supplementing with a precise amount of glucanase, it enables efficient production of XG and XGOS, offering a novel strategy for high‐yield.