Application of Immobilized Ipomoea batata β Amylase in the Saccharification of Starch

Abstract

Present study demonstrates the immobilization of acetone fractionated Ipomoea batata (sweet potato) β amylase on an inorganic support, Celite-545 by simple adsorption mechanism. The adsorbed enzyme exhibited an activity yield of 244 U g-1 of the matrix with effectiveness factor ‘η’ 0.83. Interaction between Celite-545 and enzyme was confirmed by fourier transform infrared spectroscopy and atomic force microscopy. The binding efficiency of enzyme to the support was analyzed by eluting it with 1.0 M NaCl. Both soluble and immobilized β amylase exhibited same pH optima while temperature optimum of immobilized enzyme was shifted from 50oC to 60oC. The immobilized β amylase preparation was superior to the free enzyme in hydrolyzing starch in a batch process: it hydrolyzed starch to 88% and 96% at 40oC and 50oC, respectively whereas soluble enzyme hydrolyzed only 83% and 80% of starch under similar experimental conditions. The immobilized β amylase retained 84% of its original activity after 30 days storage at 4oC, while the soluble enzyme showed only 41% of the initial activity under identical conditions. Immobilized β amylase retained 79% activity even after its 7th repeated use

Keywords

• β amylase, Celite-545, immobilization, sweet potato, batch processAbbreviations: AFM, atomic force microscopy, DNS, 3,5 dinitro-salicylic acid, FT-IR, fourier transform infrared spectroscopy