Efficient cascade biosynthesis of (S)-2-hydroxybutyric acid.
- Author:
Lingzhi TIAN
1
;
Junping ZHOU
1
;
Taowei YANG
1
;
Xian ZHANG
1
;
Minglong SHAO
1
;
Meijuan XU
1
;
Zhiming RAO
1
Author Information
- Publication Type:Journal Article
- Keywords: (S)-2-hydroxybutyric acid; NADH regeneration; cascade biocatalysis; multi-enzyme-coordinated expression system; promoter engineering
- MeSH: Escherichia coli/genetics*; Formate Dehydrogenases; Hydroxybutyrates; Threonine Dehydratase
- From: Chinese Journal of Biotechnology 2021;37(12):4231-4242
- CountryChina
- Language:Chinese
- Abstract: 2-Hydroxybutyric acid (2-HBA) is an important intermediate for synthesizing biodegradable materials and various medicines. Chemically synthesized racemized 2-HBA requires deracemization to obtain optically pure enantiomers for industrial application. In this study, we designed a cascade biosynthesis system in Escherichia coli BL21 by coexpressing L-threonine deaminase (TD), NAD-dependent L-lactate dehydrogenase (LDH) and formate dehydrogenase (FDH) for production of optically pure (S)-2-HBA from bulk chemical L-threonine (L-Thr). To coordinate the production rate and the consumption rate of the intermediate 2-oxobutyric acid in the multi-enzyme cascade catalytic reactions, we explored promoter engineering to regulate the expression levels of TD and FDH, and developed a recombinant strain P21285FDH-T7V7827 with a tunable system to achieve a coordinated multi-enzyme expression. The recombinant strain P21285FDH-T7V7827 was able to efficiently produce (S)-2-HBA with the highest titer of 143 g/L and a molar yield of 97% achieved within 16 hours. This titer was approximately 1.83 times than that of the highest yield reported to date, showing great potential for industrial application. Our results indicated that constructing a multi-enzyme-coordinated expression system in a single cell significantly contributed to the biosynthesis of hydroxyl acids.
