Enhanced cadaverine production from l-lysine using recombinant Escherichia coli co-overexpressing CadA and CadB
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The effect of fusing the PelB signal sequence to lysine/cadaverine antiporter (CadB) on the bioconversion of l-lysine to cadaverine was investigated. To construct a whole-cell biocatalyst for cadaverine production, four expression plasmids were constructed for the co-expression of lysine decarboxylase (CadA) and lysine/cadaverine antiporter (CadB) in Escherichia coli. Expressing CadB with the PelB signal sequence increased cadaverine production by 12 %, and the optimal expression plasmid, pETDuet-pelB-CadB-CadA, contained two T7 promoter-controlled genes, CadA and the PelB-CadB fusion protein. Based on pETDuet-pelB-CadB-CadA, a whole-cell system for the bioconversion of l-lysine to cadaverine was constructed, and three strategies for l-lysine feeding were evaluated to eliminate the substrate inhibition problem. A cadaverine titer of 221 g l−1 with a molar yield of 92 % from lysine was obtained.
KeywordsCadaverine Co-expression Lysine/cadaverine antiporter PelB Whole-cell bioconversion
This work was supported by the National Nature Science Foundation of China (Grant nos. 21390200 and 21106068), the National Key Technology Support Program (Grant no. 2012BAI44G00), the “973” Program of China (Grant no. 2011CBA00807), and the “863” Program of China (Grant no. 2014AA021703).
Supplementary Methods—Determination of cadaverine.
Supplementary Table 1—Strains and plasmids used in this work.
Supplementary Table 2—Primers used in this work (restriction sites are underlined).
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