Optimization production of acid urease by Enterobacter sp. in an approach to reduce urea in Chinese rice wine

摘要

Urea in alcoholic beverages is a precursor of ethyl carbamate, which is carcinogenic. Acid urease (EC 3.5.1.5) is regarded as a good approach to scavenge the urea. The acid urease of Enterobacter sp. R-SYB082, with lower optimum pH than the widely used commercial acid urease, exhibited a urea removal rate of 66.5% in Chinese rice wine, which was higher than that of the commercial acid urease (58.9%). The production of the acid urease was optimized from 1,100 to 2,504 UL~(-1) by an approach which includes the optimization of initial glucose concentration, the elevation of anaerobic level of the reactor by charging CO_2 and in vitro natural activation of the target enzyme by simple cold storage (4℃). These would open up the possibility for developing industrial application of this acid urease for producing high-quality Chinese rice wine.