Production method of high-activity dextransucrase

The invention discloses a production method of high-activity dextransucrase, which comprises the following steps: fermenting leuconostoc mesenteroides in an enzyme-producing culture medium containing 2-8% of dextran with the weight-average molecular weight of less than 100kDa for 15-20 hours by using a fermentation-affinity-membrane separation coupling technology to obtain high-activity dextransucrase fermentation liquor; and filtering by using a membrane to remove small molecular impurities in the fermentation liquor, concentrating, and centrifugally degerming to obtain the high-activity dextransucrase preparation with good stability. The average enzyme activity of the fermentation liquor reaches 22 U/ml or above, the highest enzyme activity is two times or above of that of a control, the purified dextransucrase crude enzyme liquid exceeds 100 U/ml, and the dextransucrase crude enzyme liquid can be stably stored for 3 months or above at the temperature of 2-8 DEG C and can meet the requirement for synthesizi