Kinetics of fungal extracellular alpha-amylase from Fusarium solani immobilized in calcium alginate beads.

Extracellular alpha-amylase mass produced by Fusarium solani using mango kernel as substrate was immobilized in calcium alginate beads through entrapment technique. Maximum enzyme immobilization efficiency was achieved in 2 mm size beads formed by 6.5% (w/v) of sodium alginate in 2% (w/v) calcium chloride. The catalytic properties of the immobilized alpha-amylase were compared with that of free enzyme (soluble). The activity yield of the immobilized enzyme was 81% of the free enzyme. The immobilized enzyme showed optimum activityat pH 4.5-6.0 and temperature 40 degrees C, in contrast to the free enzyme at 5.5 and 30 degrees C, respectively. Thermal stability of the immobilized enzyme was found to be more than the free enzyme over a longer time interval. The immobilized enzyme retained activity upto 20% of optimum even after 180 min. While the free enzyme lost its 80% activity after 60 min and lost total activity down to zero by 120 min. The kinetic constants, viz., K(M) (Michaelis constant), V(max) and activation energy were affected by immobilization. However, the immobilized alpha-amylase in calcium alginate beads supports its long-term storage which has immense industrial applications.