Characterization of a New Marine Leucine Dehydrogenase from Pseudomonas balearica and Its Application for L-tert-Leucine Production

Leucine dehydrogenase (LeuDH) has emerged as the most promising biocatalyst for L-tert-leucine (L-Tle) production via asymmetric reduction in trimethylpyruvate (TMP). In this study, a new LeuDH namedPbLeuDH from marinePseudomonas balearicawas heterologously over-expressed inEscherichia coli, followed by purification and characterization.PbLeuDH possessed a broad substrate scope, displaying activities toward numerous L-amino acids andα-keto acids. Notably, compared with those reported LeuDHs,PbLeuDH exhibited excellent catalytic efficiency for TMP with aKmvalue of 4.92 mM and akcat/Kmvalue of 24.49 s−1mM−1. Subsequently, L-Tle efficient production was implemented from TMP by whole-cell biocatalysis using recombinantE. colias a catalyst, which co-expressedPbLeuDH and glucose dehydrogenase (GDH). Ultimately, using a fed-batch feeding strategy, 273 mM (35.8 g L−1) L-Tle was achieved with a 96.1% yield and 2.39 g L−1h−1productivity. In summary, our research provides a competitive biocatalyst for L-Tle green biosynthesis and lays a solid foundation for the realization of large-scale L-Tle industrial production.Keywords:leucine dehydrogenase;L-tert-leucine;trimethylpyruvate;reductive amination;whole-cell biocatalysis