Print Email Facebook Twitter Engineering NADH/NAD+ ratio in Halomonas bluephagenesis for enhanced production of polyhydroxyalkanoates (PHA) Title Engineering NADH/NAD+ ratio in Halomonas bluephagenesis for enhanced production of polyhydroxyalkanoates (PHA) Author Ling, Chen (Tsinghua University) Qiao, Guan Qing (Tsinghua University) Shuai, Bo Wen (Tsinghua University) Olavarria, Karel (TU Delft OLD BT/Cell Systems Engineering) Yin, Jin (Tsinghua University) Xiang, Rui Juan (Bluepha) Song, Kun Nan (Tsinghua University) Shen, Yun Hao (Tsinghua University) Guo, Yingying (Tsinghua University) Chen, G. (Tsinghua University) Date 2018 Abstract Halomonas bluephagenesis has been developed as a platform strain for the next generation industrial biotechnology (NGIB) with advantages of resistances to microbial contamination and high cell density growth (HCD), especially for production of polyhydroxyalkanoates (PHA) including poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). However, little is known about the mechanism behind PHA accumulation under oxygen limitation. This study for the first time found that H. bluephagenesis utilizes NADH instead of NADPH as a cofactor for PHB production, thus revealing the rare situation of enhanced PHA accumulation under oxygen limitation. To increase NADH/NAD+ ratio for enhanced PHA accumulation under oxygen limitation, an electron transport pathway containing electron transfer flavoprotein subunits α and β encoded by etf operon was blocked to increase NADH supply, leading to 90% PHB accumulation in the cell dry weight (CDW) of H. bluephagenesis compared with 84% by the wild type. Acetic acid, a cost-effective carbon source, was used together with glucose to balance the redox state and reduce inhibition on pyruvate metabolism, resulting in 22% more CDW and 94% PHB accumulation. The cellular redox state changes induced by the addition of acetic acid increased 3HV ratio in its copolymer PHBV from 4% to 8%, 4HB in its copolymer P34HB from 8% to 12%, respectively, by engineered H. bluephagenesis. The strategy of systematically modulation on the redox potential of H. bluephagenesis led to enhanced PHA accumulation and controllable monomer ratios in PHA copolymers under oxygen limitation, reducing energy consumption and scale-up complexity. Subject etfHalomonasNADHNADH/NADNext generation industrial biotechnologyOxygen limitationPHBPolyhydroxyalkanoates To reference this document use: http://resolver.tudelft.nl/uuid:e367dedc-7540-4a06-8b43-f78fcf642f66 DOI https://doi.org/10.1016/j.ymben.2018.09.007 Embargo date 2019-09-18 ISSN 1096-7176 Source Metabolic Engineering, 49, 275-286 Bibliographical note Accepted Author Manuscript Part of collection Institutional Repository Document type journal article Rights © 2018 Chen Ling, Guan Qing Qiao, Bo Wen Shuai, Karel Olavarria, Jin Yin, Rui Juan Xiang, Kun Nan Song, Yun Hao Shen, Yingying Guo, G. Chen Files PDF accepted_Ling_Chen_and_co ... s_2018.pdf 2.37 MB Close viewer /islandora/object/uuid:e367dedc-7540-4a06-8b43-f78fcf642f66/datastream/OBJ/view