发酵生产环氧琥珀酸水解酶的研究

诺卡氏菌环氧琥珀酸水解酶是胞内酶,提高发酵过程酶的产量可以从提高菌体质量浓度和提高比酶活两方面入手。菌体质量浓度和培养基中葡萄糖的质量浓度有关,但葡萄糖质量浓度过高对菌体的生长会有抑制作用,培养基中初始葡萄糖质量浓度为5g/L,在消耗殆尽后以1.3g/(L·h)的速度流加,可以将菌体质量浓度提高到6g/L以上。环氧琥珀酸采用两段式流加,流加结束时比酶活达到3000u/g以上,菌体质量浓度达到了8g/L,与原产酶水平1200u/g和菌体质量浓度4g/L相比有较大的提高。

Epoxysuccinate hydrolase production in fed-batch cultivation of Nocardia sp.

Epoxysuccinate hydrolase is an intracellular enzyme of Nocardia sp. There are two ways to improve the enzyme production. One is to increase the concentration of cells,and the other is to enhance the specific enzymatic activity. Cell concentration was dependent on the amount of glucose in the medium, but high concentration of glucose inhibited the growth of cells. The culture medium contained about 5 g/L glucose at the beginning of fermentation. When glucose was consumed up, a glucose solution was continuously added at 1.3 g/(L·h), and the cell density reached 6 g/L at the end of feeding of glucose. The feeding rate of cis epoxysuccinic acid was increased at the late period of the induction phase to maintain a sufficient level of the inducer. In fed batch fermentation with controlled glucose and epoxysuccinate feeding, the specific epoxysuccinate hydrolase activity and cell density reached 3000 units/g and 8 g/L respectively, much higher than 1200 units/g and 4 g/L obtained with the original strategies.