Lactose is a main by-product in the cheese industry. Many attempts have been made to convert the lactose to high value-added products, including epilactose. Epilactose is a valuable prebiotic and can be epimerized from lactose with cellobiose 2-epimerase (CEase). The objective of the present work was to construct a food-grade recombinant Bacillus subtilis that produces CEase from Thermoanaerobacterium saccharolyticum. The CEase was expressed in B. subtilis without antibiotic resistance genes. After fermentation, the maximum volumetric activity of the fermented broth was more than 7 U/mL. The activity of the recombinant B. subtilis was increased by up to 3.7 fold after ethanol permeabilization. Then, 66.9 ± 0.7 g/L of epilactose was produced from 300 g/L of whey powder solution in 1 h with 13.3 U/mL of permeabilized biocatalyst. In addition, an enzymatic route including degradation of the lactose, yeast fermentation, and cation exchange chromatography was described to further purify the produced epilactose from lactose. Finally, epilactose with a purity >98% was produced from 300 g/L of lactose with a yield of 24.0%. In conclusion, neither antibiotics nor pathogenic bacteria were used throughout the epilactose production and purification procedure.

乳糖是奶酪行业的主要副产品。已经进行了许多尝试来将乳糖转化为高附加值的产品，包括表乳糖。癫pil糖是一种有价值的益生元，可以与纤维二糖2-表异构酶（CEase）一起从乳糖中异构化。本工作的目的是构建食品级重组枯草芽孢杆菌，该枯草芽孢杆菌由解热嗜热厌氧杆菌产生CEase 。CEase在没有抗生素抗性基因的枯草芽孢杆菌中表达。发酵后，发酵液的最大体积活性超过7 U / mL。重组枯草芽孢杆菌的活性乙醇通透后，其增加高达3.7倍。然后，用13.3 U / mL的可渗透生物催化剂，在1小时内从300 g / L的乳清粉溶液中产生66.9±0.7 g / L的表乳糖。另外，描述了包括乳糖降解，酵母发酵和阳离子交换色谱的酶促途径，以进一步从乳糖中纯化产生的表乳糖。最后，从300 g / L的乳糖中产生纯度> 98％的表乳糖，产率为24.0％。总之，在整个表皮糖的生产和纯化过程中，既没有使用抗生素也没有使用致病菌。