生物转化生产D-塔格糖的食品级菌种选育及L-阿拉伯糖异构酶的克隆表达

Screening of food-grade microorganisms for biotransformation of D-tagatose and cloning and expression of L-arabinose isomerase

摘要:

L-阿拉伯糖异构酶 (L-arabinose isomerase，L-AI) 是一种可以催化D-半乳糖为D-塔格糖的胞内异构化酶。随着塔格糖在食品工业中越来越广泛的应用，能够将半乳糖转化为塔格糖的食品级微生物以及食品级来源的L-AI受到更大的关注。文中从各种酸奶制品、泡菜及其他一些食品中采集不同的样品，筛选出1株具有L-AI酶活的食品级菌株，经过生理生化鉴定以及16S rDNA序列测定，确定该菌株为戊糖片球菌，命名为Pediococcus pentosaceus PC-5。以该菌基因组为模板，克隆L-AI

Abstract:

L-Arabinose isomerase (L-AI) is an intracellular enzyme that catalyzes the reversible isomerization of D-galactose and D-tagatose. Given the widespread use of D-tagatose in the food industry, food-grade microorganisms and the derivation of L-AI for the production of D-tagatose is gaining increased attention. In the current study, food-grade strains from different foods that can convert D-galactose to D-tagatose were screened. According to physiological, biochemical, and 16S rDNA gene analyses, the selected strain was found to share 99% identity with Pediococcus pentosaceus, and was named as Pediococcus pentosaceus PC-5. The araA gene encoding L-AI from Pediococcus pentosaceus PC-5 was cloned and overexpressed in E .coli BL21. The yield of D-tagatose using D-galactose as the substrate catalyzed by the crude enzyme in the presence of Mn2+ was found to be 33% at 40 °C.