Enhanced biosynthesis of chiral phenyllactic acid from l-phenylalanine through a new whole-cell biocatalyst
Phenyllactic acid (PLA) is a high-value compound, which was usually produced by lactic acid bacteria (LAB) as biocatalysts and glucose or phenylpyruvic acid (PPA) as starting materials for PLA synthesis in previous studies. However, the PLA produced using LAB is a racemic mixture. Besides, both glucose and PPA were unsatisfactory substrates, as the former could not produce high concentrations of PLA while the latter is not a renewable and green substrate. To overcome these drawbacks, in this study, a new biotransformation process was developed for chiral PLA production from l-phenylalanine via the intermediate PPA using recombinant Escherichia coli co-expressing l-amino acid deaminase, NAD-dependent l-lactate dehydrogenase or NAD-dependent d-lactate dehydrogenase, and formate dehydrogenase. After optimization, the recombinant E. coli produced l- and d-PLA at concentrations of 59.9 and 60.3 mM in 6 h, respectively. Hence, this process provides an effective and promising alternative method for chiral PLA production.
KeywordsChiral phenyllactic acid l-Amino acid deaminase NAD-dependent l- or d-lactate dehydrogenase l-Phenylalanine Biotransformation
We acknowledge financial support from the National Key Research & Development Program of China (2017YFD0600205), the National Natural Science Foundation of China (31300487), the Major Program of the Natural Science Foundation of Jiangsu Higher Education of China (16KJA220004), and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).
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Conflict of interest
All authors declare no conflict of interest, financially or otherwise.
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