Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, Yunnan Normal University, Kunming 650500, China; State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu 214122, China.
State Key Laboratory of Food Science and Resources, Jiangnan University, Wuxi, Jiangsu 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
Int J Biol Macromol. 2024 Nov;280(Pt 4):136063. doi: 10.1016/j.ijbiomac.2024.136063. Epub 2024 Sep 26.
Epilactose, a lactose derivative known for its prebiotic properties and potential health benefits, has garnered significant interest. Cellulose 2-epimerase (CEase) is responsible for catalyzing the conversion of lactose to epilactose. In this study, the enhancement of food-grade CEase expression in Bacillus subtilis WB600 was systematically investigated. Among seven selected epilactose-producing CEases, Rhodothermus marinus CEase (RmCE) exhibited the highest epimerization activity when expressed in B. subtilis. Translational and transcriptional regulations were employed to enhance CEase expression by screening effective N-terminal coding sequences (NCSs) and promoters. The final strain demonstrated efficient production of CEase, with epimerization activity reaching 273.6 ± 6.5 U/mL and 1255 ± 26.4 U/mL in shake-flask and fed-batch cultivation, respectively. Utilizing only 0.25 % (V/V) of the fed-batch cultivation broth for lactose biotransformation, epilactose was efficiently produced from 300 g/L of lactose within 4 h, achieving a yield of 29.5 %. These findings provide significant support for the potential industrialization of enzymatic epilactose production.
已酰化乳糖，一种具有益生元特性和潜在健康益处的乳糖衍生物，引起了广泛关注。纤维素 2-差向异构酶（CEase）负责催化乳糖向已酰化乳糖的转化。在本研究中，系统研究了在枯草芽孢杆菌 WB600 中增强食品级 CEase 表达。在 7 种筛选出的产已酰化乳糖的 CEases 中，海洋栖热菌 CEase（RmCE）在枯草芽孢杆菌中表达时表现出最高的差向异构化活性。通过筛选有效的 N 端编码序列（NCS）和启动子，采用翻译和转录调控来增强 CEase 的表达。最终的菌株能够高效生产 CEase，在摇瓶和分批补料培养中的差向异构化活性分别达到 273.6±6.5 U/mL 和 1255±26.4 U/mL。在分批补料培养中仅使用 0.25%（V/V）的培养物进行乳糖转化，已酰化乳糖能够在 4 小时内从 300 g/L 的乳糖中高效生产，产率为 29.5%。这些发现为酶法已酰化乳糖生产的工业化应用提供了重要支持。
