Enhancing enzyme activity and enantioselectivity of Burkholderia cepacia lipase via immobilization on modified multi-walled carbon nanotubes

Abstract

Burkholderia cepacia lipase (BCL) was proved to be a potential catalyst in chiral resolution. However, it is not widely applied in industry because of the low catalysis activity and poor stability of the free lipase. In this study, BCL was immobilized on modified multi-walled carbon nanotubes to enhance its catalysis performance. The immobilization conditions were further optimized via single factorial experiments and response surface methodology (RSM). Under the optimum conditions, the enzyme activity attained was 50 200 U g⁻¹, 54 fold that of the free lipase in resolution of 1-phenylethanol, resulting in an immensely shortened reaction time from 30 h of the free lipase to 10 min of the immobilized one. SEM micrographs verified that CNTs were truncated and the closed ends were opened by concentrated H₂SO₄. EDS further confirmed the modification and successful immobilization of the lipase. FT-IR analysis demonstrated that improvement of enzyme activity and ee_s was correlated to the alteration of the secondary structure. Compared with other immobilized lipases, CNT–BCL exhibits great advantages and possesses promising potential in industrial application.