Improvement of enzymatic activity and stability of lipase A from Candida antartica onto halloysite nanotubes with Taguchi method for optimized immobilization

This research reports the immobilization by ion adsorption and interfacial activation of lipase A from Candida antarctica (CALA) in halloysite nanotubes (Hal) was optimized by the Taguchi method. Under optimized conditions (pH 5 to 5 mM, 5 C-o and 4 h), it was possible to obtain an immobilization yield (IY) of 97.1 +/- 0.10% with a mass activity (AtD) of 83.81 +/- 0 0.50 U/g for the hydrolysis of p-nitrophenyl butyrate. pH and ionic strength were the parameters that most positively influenced the optimization of the enzymatic immobilization process, favoring the activity of the catalytic derivative. At pH 7, CALA-Hal exhibited a half-life 2-8 times longer than CALA at 50-90 C-o. CALA showed maximum activity at pH 7.Especially at pH 9, CALA-Hal was more active than the native lipase at the pHs under study, expect at pH 7. CALA was partially desorbed from HNT after 2 h of incubation in 4% Triton X-100 and fully desorbed after 1 h of incubation in 1.0 M NaCl. Hal and CALA-Hal were characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscope (SEM), elemental analysis (CHNS), Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC), showing the immobilization of CALA on HNT and the maintenance of the nanotubes structure after immobilization. Therefore, the strategy employed in this study to immobilize CALA onto Hal allowed us to obtain promising results. Biocatalysts showed potential for use in diverse reactions of industrial interest.