title: Enhancing pentose phosphate pathway in Corynebacterium glutamicum to improve l-isoleucine production.
abstract: Three genes, gnd, pgl, and fbp, relevant to the pentose phosphate pathway (PPP) were overexpressed in Corynebacterium glutamicum IWJ001, leading to increase of l-isoleucine production. The transcriptional levels of gnd, pgl, and fbp significantly increased in IWJ001/pDXW-8-gnd-fbp-pgl. Compared with the control strain IWJ001/pDXW-8, intracellular NADPH/NADP+ratios in IWJ001/pDXW-8-gnd and IWJ001/pDXW-8-gnd-fbp cells grown for 36 H increased threefold and fourfold, respectively, indicating that overexpression of gnd and fbp redirected the carbon flux to PPP. Intracellular NADPH/NADP+ratio in IWJ001/pDXW-8-gnd-fbp-pgl grown for 36 H was similar to IWJ001/pDXW-8, suggesting that the NADPH produced by PPP could be quickly consumed for l-isoleucine production. 10.9 and 28.96 g/L of l-isoleucine was produced in IWJ001/pDXW-8-gnd-fbp-pgl in shake flask cultivation and fed-batch fermentation, respectively. In addition, IWJ001/pDXW-8-gnd-fbp-pgl grew fast, its dry cell weight reached 49 g/L after 48 H, whereas the start strain IWJ001/pDXW-8 reached only 40 g/L. After 96 H fermentation, l-isoleucine yield on glucose in IWJ001/pDXW-8-gnd-fbp-pgl reached 0.138 g/g. The results demonstrate that carbon flux redirection to PPP is an efficient approach to enhance l-isoleucine production in C. glutamicum.
authors.affiliation: School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China.
authors.forename: Wenjian
authors.initials: W
authors.lastname: Ma
authors.affiliation: School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China.
authors.forename: Jianli
authors.initials: J
authors.lastname: Wang
authors.affiliation: School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China.|State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.|Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, People's Republic of China.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Hu
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.|Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, People's Republic of China.
authors.forename: Feng
authors.initials: F
authors.lastname: Shi
authors.affiliation: School of Biotechnology, Jiangnan University, Wuxi, People's Republic of China.|State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, People's Republic of China.|Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, People's Republic of China.
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Wang
mesh_terms: D061249:Batch Cell Culture Techniques; D002237:Carbohydrate Dehydrogenases / Q000235:genetics; D002244:Carbon / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D007532:Isoleucine / Q000096:biosynthesis*; D060847:Metabolic Engineering / Q000379:methods*; D009249:NADP / Q000378:metabolism; D010427:Pentose Phosphate Pathway / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D007532:Isoleucine; D009249:NADP; D002244:Carbon; D002237:Carbohydrate Dehydrogenases
keywords: C. glutamicum; NADPH; branched-chain amino acids; l-isoleucine; pentose phosphate pathway