title: Construction of a novel, stable, food-grade expression system by engineering the endogenous toxin-antitoxin system in Bacillus subtilis.
abstract: Bacillus subtilis as an important workhorse that has been widely used to produce enzymes and metabolites. To broaden its applications, especially in the food and feed industry, we constructed a novel, stable, food-grade expression system by engineering its type II toxin-antitoxin system. The expression of the toxin EndoA, encoded by the chromosomal ydcE gene, was regulated by an endogenous, xylose-inducible promoter, while the ydcD gene, which encodes the unstable antitoxin EndoB, was inserted into a food-grade vector backbone, where its expression was driven by the native, constitutive promoter PylxM. By maintaining the xylose concentration above 2.0 g L(-1), this auto-regulated expression system was absolutely stable after 100 generations. Compared with traditional antibiotic-dependent expression systems, this novel expression system resulted in greater biomass and higher titers of desired products (enzymes or metabolites). Our results demonstrate that this stable, food-grade expression system is suitable for enzyme production and pathway engineering, especially for the production of food-grade enzymes and metabolites.
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China.
authors.forename: Sen
authors.initials: S
authors.lastname: Yang
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China. Electronic address: zkang@jiangnan.edu.cn.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Kang
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China.
authors.forename: Wenlong
authors.initials: W
authors.lastname: Cao
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Guocheng
authors.initials: G
authors.lastname: Du
authors.affiliation: The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi 214122, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu 214122, China. Electronic address: jchen@jiangnan.edu.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: Chen
mesh_terms: D000992:Antitoxins / Q000235:genetics*; D001412:Bacillus subtilis / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics*; D005524:Food Technology; D015964:Gene Expression Regulation, Bacterial; D005822:Genetic Vectors; D011401:Promoter Regions, Genetic; D014994:Xylose / Q000378:metabolism*
chemical_list: D000992:Antitoxins; D001427:Bacterial Toxins; D014994:Xylose
keywords: Bacillus subtilis; EndoA; EndoB; Food-grade expression system; Toxin–antitoxin