Abstract:
Extra cellular β-galactosidase enzyme was purified and characterized from Aspergillus fumigatus PCSIR2013. Estimated molecular mass of the enzyme was approximately 95 kDa. by native polyacrylamide gel electrophoresis.
Initially, different fermentation parameters were optimized for maximum production of β-galactosidase. The kinetic
study of the partially purified enzyme exhibited that it remained active in broad range of temperature from 25°C to 70°C
with an optimum of 60°C. The Km and Vmax were calculated as 9.95mmol/l and 51.78 U/ml/min, respectively. The
optimum pH was 5.0, when reaction mixture was incubated for 30 min. The enzyme was very stable in the presence of
different metal ions, although Na+
(16%) stimulates the activity at 10mM concentration. In contrast, Ba+2 and Hg+2 have
negative effect on enzyme activity and activity decreased to 54% and 19%, respectively. Thermo stability study was
revealed that the enzyme retained 72% of its activity at 50°C. Whereas, when enzyme was incubated at 60°C for 120
min, its residual activity was decreased to 42.0%. However, the enzyme was completely inactivated at 80°C after 120
min of pre-incubation. Among different surfactant which incorporated with enzyme, Tween 20 and Triton X-100 both
have stimulatory effect and activity increased to 29% and 17%, respectively.
