1State Key Laboratory of Bioreactor Engineering, Shanghai Collaborative Innovation Center for Biomanufacturing Technology, School of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China
2MOE Key Laboratory of Bio-Intelligent Manufacturing, School of Bioengineering, Dalian University of Technology, Dalian, China
3Key Laboratory of Bio-based Material Engineering of China National Light Industry Council, 130 Meilong Road, Shanghai, 200237, China
| Received 22 Feb 2025 |
Accepted 03 May 2025 |
Published 06 Jun 2025 |
In this study, a platform was constructed for the efficient biosynthesis of a lactate-based copolymer using a phosphite dehydrogenase (PtxD)-based NADH regeneration strategy. PtxD catalyzes the conversion of phosphite to phosphate while reducing NAD + to NADH. The latter is an essential cofactor for lactate synthesis in Escherichia coli. This strategy allows the decoupling of NADH regeneration from carbon metabolism flow, providing sufficient NADH for lactate synthesis. Different concentrations of isopropyl β-d-1-thiogalactopyranoside (IPTG) were used to control the intensity of PtxD expression, and the lactate fraction in the copolymer synthesized by the engineered strain ranged from 6.2 to 16.7 mol%. The ptxD gene was integrated into the genome of strain WJPCTP-01, which successfully synthesized 3.24 g/L P(3HB-co-23.0 mol% LA) and 2.23 g/L P(3HB-co-39.0 mol% LA) using glucose and xylose as substrates, respectively, in shake flask cultures. In 5 L bioreactor fermentations, the titer of P(3HB-co-41.3 mol% LA) reached 8.57 g/L, with a synthesis rate of 0.12 g/L/h when xylose was used as a substrate. These findings indicate that the PtxD-based NADH regeneration strategy enhances lactate synthesis without any significant negative impact on bacterial growth or the synthesis of P(3HB-co-LA).
