Enhancement of pipecolic acid production by the expression of multiple
lysine cyclodeaminase in the Escherichia coli whole-cell system
Abstract
Pipecolic acid, a non-proteinogenic amino acid, is a metabolite in
lysine metabolism and a key chiral precursor in local anesthesia and
macrolide antibiotics. To replace the environmentally unfriendly
chemical production or preparation procedure of pipecolic acid, many
biological synthetic routes have been studied for a long time. Among
them, synthesis by lysine cyclodeaminase (LCD), encoded by pipA, has
several advantages, including stability of enzyme activity and NAD+
self-regeneration. Thus, we selected this enzyme for pipecolic acid
biosynthesis in a whole-cell bioconversion. To construct a robust
pipecolic acid production system, we investigated important conditions
including expression vector, strain, culture conditions, and other
reaction parameters. The most important factors were introduction of
multiple pipA genes into the whole-cell system and control of agitation.
As a result, we produced 724 mM pipecolic acid (72.4% conversion), and
the productivity was 0.78 g/L/h from 1 M L-lysine after 5 days. This is
the highest production reported to date.