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

ABSTRACT

Extracellular a-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 a-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 activity at pH 4.5-6.0 and temperature 40 ºC, in contrast to the free enzyme at 5.5 and 30ºC, 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., KM (Michaelis constant), Vmax and activation energy were affected by immobilization. However, the immobilized a-amylase in calcium alginate beads supports its long term storage which has immense industrial applications.