title: Improvement of exopolysaccharide production in Lactobacillus casei LC2W by overexpression of NADH oxidase gene.
abstract: Lactobacillus casei LC2W is an exopolysaccharide (EPS)-producing strain with probiotic effects. To investigate the regulation mechanism of EPS biosynthesis and to improve EPS production through cofactor engineering, a H₂O-forming NADH oxidase gene was cloned from Streptococcus mutans and overexpressed in L. casei LC2W under the control of constitutive promoter P₂₃. The recombinant strain LC-nox exhibited 0.854 U/mL of NADH oxidase activity, which was elevated by almost 20-fold in comparison with that of wild-type strain. As a result, overexpression of NADH oxidase resulted in a reduction in growth rate. In addition, lactate production was decreased by 22% in recombinant strain. It was proposed that more carbon source was saved and used for the biosynthesis of EPS, the production of which was reached at 219.4 mg/L, increased by 46% compared to that of wild-type strain. This work provided a novel and convenient genetic approach to manipulate metabolic flux and to increase EPS production. To the best of our knowledge, this is the first report which correlates cofactor engineering with EPS production.
authors: State Key Laboratory of Dairy Biotechnology, Dairy Research Institute, Bright Dairy & Food Co., Ltd., PR China.
authors: Nan
authors: N
authors: Li
authors: State Key Laboratory of Dairy Biotechnology, Dairy Research Institute, Bright Dairy & Food Co., Ltd., PR China.
authors: Yuanlong
authors: Y
authors: Wang
authors: State Key Laboratory of Dairy Biotechnology, Dairy Research Institute, Bright Dairy & Food Co., Ltd., PR China.
authors: Ping
authors: P
authors: Zhu
authors: State Key Laboratory of Dairy Biotechnology, Dairy Research Institute, Bright Dairy & Food Co., Ltd., PR China.
authors: Zhenmin
authors: Z
authors: Liu
authors: State Key Laboratory of Dairy Biotechnology, Dairy Research Institute, Bright Dairy & Food Co., Ltd., PR China.
authors: Benheng
authors: B
authors: Guo
authors: State Key Laboratory of Dairy Biotechnology, Dairy Research Institute, Bright Dairy & Food Co., Ltd., PR China. Electronic address: renjing@brightdairy.com.
authors: Jing
authors: J
authors: Ren
mesh_terms: D003001:Cloning, Molecular; D005285:Fermentation; D015870:Gene Expression; D005798:Genes, Bacterial; D007780:Lacticaseibacillus casei / Q000235:genetics* / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics*; D009154:Mutation; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics*; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D013302:Streptomyces / Q000235:genetics
chemical_list: D009097:Multienzyme Complexes; D011135:Polysaccharides, Bacterial; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases
keywords: Cofactor engineering; Exopolysaccharide; Lactobacillus casei; NADH oxidase; Overexpression