Immobilization of Cryptococcus flavus [alpha]-amylase on glass tubes and its application in starch hydrolysis

[alpha]-Amylase from Cryptococcus flavus was previously purified after exchange chromatography on Q-Sepharose and gel filtration on Sephacryl S-100. The enzyme was purified 128-fold with a recovery rate of 81% of activity. The molecular mass of the [alpha]-amylase was 67kDa as determined by SDS-PAGE. The enzyme was characterized after immobilization on glass tubes. The immobilization yield, efficiency, and activity recovery of [alpha]-amylase were 79, 57, and 45%, respectively. The optimum pH of the immobilized enzyme was shifted to a more acidic pH (4.5) compared with the free enzyme (5.5). The optimum temperature of the immobilized enzyme was the same for the free enzyme (50°C), but it showed a higher thermal stability. The immobilized enzyme showed activity until the 10th cycle, maintaining 47% of initial activity, and was capable of hydrolyzing starch from potato, wheat, corn, and cassava. The main products released from starch were maltose, maltotriose, and maltotetraose.