Partial purification and characterization of <img src='/image/spc_char/alpha.gif'> -amylase produced by <i style="">Aspergillus oryzae</i> using spent-brewing grains

Abstract

Solid-state fermentation (SSF) was carried out to produce <img src='/image/spc_char/alpha.gif'> -amylase from <i style="">Aspergillus oryzae</i> (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 <img src='/image/spc_char/alpha.gif'> -amylase. It was optimally active at <i style="">p</i>H 5 and 50°C by using 1% starch as substrate concentration. The partially purified <img src='/image/spc_char/alpha.gif'> -amylase loses activity rapidly above 50^oC but it can be retained in the presence of Ca²⁺. Presence of Mn²⁺ and Fe²⁺ enhanced the enzyme activity and is almost doubled in presence of Mn²⁺. However, in the presence of Hg²⁺ and Cu^2+, the activity is reduced. Hg²⁺ reduced the enzyme activity by half.