Development of Alcalase-Polyacrylonitrile Nanofibrous Biocatalytic Membranes for Protein Hydrolysis

Biocatalytic membranes (BM) combine the benefits of enzymes and membranes and have found a wide variety of applications. This study focused on the development of BM by immobilizing alcalase onto electrospun polyacrylonitrile nanofibrous membranes (PANMs) modified with 1-ethyl-3-(3-dimethylamino-propyl) carbodiimide/N-hydroxy succinimide through covalent bonding. Scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterize the alcalase-functionalized PAN nanofibrous biocatalytic membrane (PAN-BM). The PAN-BM demonstrated enhanced pH and thermal stability compared to free alcalase. The BM retained 45% of its initial activity after 10 repeated uses under optimum conditions (i.e., 50 °C and pH 9.0). A BM reactor was successfully demonstrated for continuous hydrolysis of model substrate azo-casein (0.5% w/v), with its extent of hydrolysis significantly affected by both the number of layers of PAN-BM and the flux of feed. A five-layer PAN-BM was also successfully tested for continuous hydrolysis of the raw soy proteins (1.4% w/v) extracted from commercial soybean meals, showing a promising potential of application.