Partial purification and characterization of α-amylase produced by Aspergillus oryzae using spent-brewing grains

Solid-state fermentation (SSF) was carried out to produce α-amylase from Aspergillus oryzae (IFO 30103) using spent brewing grains (SBG) as substrate. A maximum of 11296 U/gds amylase activity was obtained after 48 h of fermentation. The extracted enzyme was subjected to partial purification by ammonium sulphate fractionation. Maximum specific activity was obtained with 40-70% fraction. SDS-PAGE of the corresponding sample revealed an approximate 66 kDa band, which was confirmed by activity staining as α-amylase. It was optimally active at pH 5 and 50°C by using 1% starch as substrate concentration. The partially purified α-amylase loses activity rapidly above 50C but it can be retained in the presence of Ca. Presence of Mn and Fe enhanced the enzyme activity and is almost doubled in presence of Mn. However, in the presence of Hg and Cu the activity is reduced. Hg reduced the enzyme activity by half.