Li Xu, Xu Shuqin, Zhang Xian, Xu Meijuan, Yang Taowei, Wang Li, Zhang Huiling, Fang Haitian, Osire Tolbert, Yang Shangtian, Rao Zhiming
The Key Laboratory of Industrial Biotechnology Ministry of Education School of Biotechnology Jiangnan University Wuxi P. R. China.
School of Food Science and Technology Jiangnan University Wuxi P. R. China.
Eng Life Sci. 2019 Feb 13;19(3):229-239. doi: 10.1002/elsc.201800166. eCollection 2019 Mar.
l-asparaginase has high application value in medicine and food industry, but the low yield limits its application. In this study, we designed a synthetic system in to produce l-asparaginase by improving gene expression and optimizing the fermentation agitation speed. Gene expression was improved by respectively increasing transcription levels and translation speeds through screening promoters and RBS sequences. With the optimal promoter, P43, and the synthetic RBS sequence, the yield obtained in a shake flask was 371.87 U/mL, which was 2.09 times that with the original strain. To further enhance production in a 5-L fermenter, a multistage agitation speed control strategy was adopted, involving agitation at 600 rpm for the first 12 h, followed by a gradual increase in speed to 900 rpm, which resulted in the highest yield of l-asparaginase, 5321 U/mL, after 42 h of fermentation.
L-天冬酰胺酶在医药和食品工业中具有很高的应用价值，但产量低限制了其应用。在本研究中，我们设计了一个合成系统，通过改善基因表达和优化发酵搅拌速度来生产L-天冬酰胺酶。通过筛选启动子和核糖体结合位点（RBS）序列分别提高转录水平和翻译速度来改善基因表达。使用最佳启动子P43和合成RBS序列，摇瓶中获得的产量为371.87 U/mL，是原始菌株的2.09倍。为了进一步提高在5-L发酵罐中的产量，采用了多级搅拌速度控制策略，即前12小时以600 rpm搅拌，然后逐渐将速度提高到900 rpm，发酵42小时后L-天冬酰胺酶的产量最高，达到5321 U/mL。
