Production and Characterization of "-Amylase from Aspergillus niger JGI 24 Isolated in Bangalore

Five fungal isolates were screened for the production of "-amylase using both solid-state and submerged fermentations. The best amylase producer among them, Aspergillus niger JGI 24, was selected for enzyme production by solid-state fermentation (SSF) on wheat bran. Different carbon and nitrogen supplements were used to enhance enzyme production and maximum amount of enzyme was obtained when SSF was carried out with soluble starch and beef extract (1% each) as supplements. Further attempts to enhance enzyme production by UV induced mutagenesis were carried out. Survival rate decreased with increase in duration of UV exposure. Partial purification of the enzyme using ammonium sulphate fractionation resulted in 1.49 fold increase in the enzyme activity. The enzyme showed a molecular weight of 43 kDa by SDS-PAGE. Metal ions Ca and Co increased the enzyme activity. The enzyme was optimally active at 30°C and pH 9.5. K e y w o r d s: Aspergillus niger JGI 24, "-amylase, mineral salt medium, solid-state fermentation, wheat bran * Corresponding author: K.N. Varalakshmi, Department of Biotechnology, Centre for Post-Graduate Studies, Shri Bhagawan Mahaveer Jain College, 18/3, 9th Main, 3rd Block, Jayanagar, Bangalore – 560 011; phone: (91 80) 41502411, 41210691; e-mail: [email protected]; [email protected] 30 Varalakshmi et al. 1