title: Efficient production of lactulose from whey powder by cellobiose 2-epimerase in an enzymatic membrane reactor.
abstract: In this study, the gene encoding cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus (CsCE) was successfully expressed in Bacillus subtilis WB800. After the fermentation medium optimization, the activity of recombinant strain was 4.5-fold higher than the original medium in a 7.5L fermentor. The optimal catalytic pH and temperature of crude CsCE were 7.0 and 80°C, respectively. An enzymatic synthesis of lactulose was developed using cheese-whey lactose as its substrate. The maximum conversion rate of whey powder obtained was 58.5% using 7.5 U/mL CsCE. The enzymatic membrane reactor system exhibited a great operational stability, confirmed with the higher lactose conversion (42.4%) after 10 batches. To our best knowledge, this is the first report of lactulose synthesis in food grade strain, which improve the food safety, and we not only realize the biological production of lactulose, but also make good use of industrial waste, which have positive impact on environment.
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing 211816, China; College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
authors.forename: Lingtian
authors.initials: L
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing 211816, China; College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
authors.forename: Cen
authors.initials: C
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing 211816, China; College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
authors.forename: Sha
authors.initials: S
authors.lastname: Li
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing 211816, China; College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Liang
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing 211816, China; College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing 211816, China; College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China. Electronic address: xuzheng@njtech.edu.cn.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Xu
mesh_terms: D002475:Cellobiose; D007785:Lactose; D007792:Lactulose / Q000378:metabolism*; D019998:Racemases and Epimerases; D000067796:Whey
chemical_list: D002475:Cellobiose; D007792:Lactulose; D019998:Racemases and Epimerases; D007785:Lactose
keywords: Bacillus subtilis; Biologic membrane reactor; Cellobiose 2-epimerase; Enzymic catalysis; Lactulose; Whey powder