Efficient production of 5-aminovalerate from l-lysine by engineered Escherichia coli whole-cell biocatalysts
2016
Wang, Xin | Cai, Peipei | Chen, Kequan | Ouyang, Pingkai
In this study, we developed a whole-cell biocatalysis process for high-level conversion of l-lysine into 5-aminovalerate. To obtain the highly efficient whole-cell biocatalyst, five expression plasmids were constructed to optimize the expression of 5-aminovaleramide amidohydrolase and l-lysine 2-monooxygenase in Escherichia coli. The engineered strain BL-22A-RB-YB harboring plasmid pET22b-davA, pRSFDuet-davB and pACYCDuet-davB was correspondingly obtained. Subsequently, the effects of induction conditions, reaction temperature, metal ion additives, and cell permeability on the whole-cell biocatalyst system were evaluated to improve biocatalytic efficiency. Under optimized reaction conditions, 95.3g/L 5-aminovalerate was synthesized from 120g/L l-lysine with a yield of 99.1%, and 103.1g/L 5-aminovalerate was produced from 150g/L l-lysine with a molar yield of 85.7%. The 5-aminovalerate production was then further improved using a l-lysine fed-batch strategy, and a hyper 5-aminovalerate production of 240.7g/L was achieved within 28h with a yield of 86.8%. The whole-cell biocatalytic system described here demonstrated an environmentally friendly strategy for industrial production of 5-aminovalerate.
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