Enhancement of the thermal and alkaline pH stability of Escherichia coli lysine decarboxylase for efficient cadaverine production.

OBJECTIVE:To enhance the thermal and alkaline pH stability of the lysine decarboxylase from Escherichia coli (CadA) by engineering the decameric interface and explore its potential for industrial applications. RESULTS:The mutant T88S was designed for improved structural stability by computational analysis. The optimal pH and temperature of T88S were 7.0 and 55 °C (5.5 and 50 °C for wild-type). T88S showed higher thermostability with a 2.9-fold increase in the half-life at 70 °C (from 11 to 32 min) and increased melting temperature (from 76 to 78 °C). Additionally, the specific activity and pH stability (residual activity after 10 h incubation) of T88S at pH 8.0 were increased to 164 U/mg and 78% (58 U/mg and 57% for wild-type). The productivity of cadaverine with T88S (284 g L-lysine L^-1 and 5 g DCW L^-1) was 40 g L^-1 h^-1, in contrast to 28 g L^-1 h^-1 with wild-type. CONCLUSION:The mutant T88S showed high thermostability, pH stability, and activity at alkaline pH, indicating that this mutant is a promising biocatalyst for industrial production of cadaverine.

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