| Summary: | Salvianic acid A (SAA), as the main bioactive component of the traditional Chinese herb <i>Salvia miltiorrhiza</i>, has important application value in the treatment of cardiovascular diseases. In this study, a two-step bioprocess for the preparation of SAA from <span style="font-variant: small-caps;">l</span>-DOPA was developed. In the first step, <span style="font-variant: small-caps;">l</span>-DOPA was transformed to 3,4-dihydroxyphenylalanine (DHPPA) using engineered <i>Escherichia coli</i> cells expressing membrane-bound L-amino acid deaminase from <i>Proteus vulgaris.</i> After that, the unpurified DHPPA was directly converted into SAA by permeabilized recombinant <i>E. coli</i> cells co-expressing <span style="font-variant: small-caps;">d</span>-lactate dehydrogenase from <i>Pediococcus acidilactici</i> and formate dehydrogenase from <i>Mycobacterium vaccae</i> N10. Under optimized conditions, 48.3 mM of SAA could be prepared from 50 mM of <span style="font-variant: small-caps;">l</span>-DOPA, with a yield of 96.6%. Therefore, the bioprocess developed here was not only environmentally friendly, but also exhibited excellent production efficiency and, thus, is promising for industrial SAA production.
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