Biosynthetic L-tert-leucine using Escherichia coli co-expressing a novel NADH-dependent leucine dehydrogenase and a formate dehydrogenase

Background L- tert -Leucine has been widely used in pharmaceutical, chemical, and other industries as a vital chiral intermediate. Compared with chemical methods, enzymatic methods to produce L- tert -leucine have unparalleled advantages. Previously, we found a novel leucine dehydrogenase from the halophilic thermophile Laceyella sacchari ( Ls LeuDH) that showed good thermostability and great potential for the synthesis of L- tert -leucine in the preliminary study. Hence, we manage to use the Ls LeuDH coupling with a formate dehydrogenase from Candida boidinii ( Cb FDH) in the biosynthesis of L- tert -leucine through reductive amination in the present study. Result The double-plasmid recombinant strain exhibited higher conversion than the single-plasmid recombinant strain when resting cells cultivated in shake flask for 22 h were used. Under the optimized conditions, the double-plasmid recombinant  E. coli  BL21 (pETDute-FDH-LDH, pACYCDute-FDH) transformed 1 mol·L -1 trimethylpyruvate (TMP) completely into L- tert -leucine with greater than 99.9% ee within 8 h. Conclusions The Ls LeuDH showed great ability to biosynthesize L- tert -leucine. In addition, it provided a new option for the biosynthesis of L- tert -leucine. How to cite Wang L, Zhu W, Gao Z, et al. Biosynthetic L- tert -leucine using Escherichia coli co-expressing a novel NADH-dependent leucine dehydrogenase and a formate dehydrogenase. Electron J Biotechnol 2020;47. https://doi.org/10.1016/j.ejbt.2020.07.001