Whole cell immobilization of thermostable α-amylase from phosphate solubilizing Bacillus thuringiensis A5-BRSC

Immobilization of the whole cell is a modern approach to fermentative production of different enzymes. The technique has several advantages including easy separation of the fermented product, least chance of contamination and no chance of wash out of cells during product recovery.

α-amylase produced from Calcium alginate entrapped cells of Bacillus thuringiensis A5-BRSC was purified by ammonium sulphate precipitation, followed by DE-52 ion exchange column chromatography. The molecular weight of the purified enzyme was determined by SDS-PAGE. Study of enzyme kinetics was performed to determine its enzymatic potency.

Immobilization of Bacillus thuringiensis A5-BRSC cells in calcium alginate resulted in more than 3.5 times higher αamylase activity than free cells within 48 hours of batch fermentation. The molecular weight of the purified enzyme was estimated to be 52 kDa by SDS-PAGE. The enzyme exhibited pH optima at 6.9 and temperature optima at 50°C. KM and Vmax of the purified enzyme was determined to be 0.85 mg/ml and 0.98 mg of liberated maltose/ml of enzyme/minute.

α-amylase produced form the immobilized cells found to be more potent than the enzyme produced by the free cells.