发酵耦合酶解高效制备右旋糖酐工艺研究

【目的】改进肠膜明串珠菌（Leuconostoc mesenteriodes 31208）发酵蔗糖制备右旋糖酐的工艺，实现灵活控制分子量及高效制备右旋糖酐的目标。【方法】采用单因素实验法研究蔗糖浓度对蔗糖转化的影响，确定蔗糖流加工艺的各个参数，以及右旋糖酐酶添加耦合蔗糖流加的工艺条件。【结果】通过调控右旋糖酐酶添加工艺，可灵活控制右旋糖酐的分子量，无需再经酸水解及乙醇分级沉淀就可以得到不同分子量的右旋糖酐，节省无水乙醇的用量；且确定的最佳蔗糖流加工艺参数：初始蔗糖浓度为130 g／L，流加速度为12 g·L－1·h－1，起始流加时间为16 h。与蔗糖单批发酵结果相比，该工艺可使蔗糖转化效率提高约75％，特定分子量（5000～7500 Da）右旋糖酐浓度可达108 g／L，相应提高2．3倍，收率稳定在32％左右。【结论】该方法具有发酵易调控、高效和成本低的优点，对大规模生产右旋糖酐具有重要的参考价值和应用价值。

Study on Efficient Preparation for Dextran by Fermentation Coupled with Enzymatic Hydrolysis

Objective]This paper aims to control dextran molecular flexibly and prepare dextran efficiently with Leuconostoc mesenteriodes 31208 by improving the preparation process.Meth-ods]The effect of sucrose concentration on sucrose conversion,the parameters of sucrose feed-ing,as well as the process conditions coupled enzymatic adding and sucrose feeding were stud-ied by means of single factor experiment.Results]The molecular weight of dextran was con-trolled flexibly by changing the enzymatic hydrolysis process,and the parameters of optimal su-crose feeding process were the initial sucrose concentration of 130 g/L with the flow accelera-tion of 12 g·L-1 ·h-1 at 16 h.Compared with the single batch fermentation,the conversion rate improved by 75% and specific-molecular dextran（5000~7500 Da）increased over time,and the yield of dextran was about 32%.Conclu-sion]This method has the characteristics of sim-ple fermentation control,high efficiency and low cost,which was important to the preparation of dextran for industrial production.