Open-access Alpha amylase from a fungal culture grown on oil cakes and its properties

Abstract

Solid-state fermentation was carried out for the production of alpha-amylase using Aspergillus oryzae. Different oil cakes such as coconut oil cake (COC) sesame oil cake (SOC), groundnut oil cake (GOC), palm kernel cake (PKC) and olive oil cake (OOC) were screened to be used as substrate for the enzyme production and also compared with wheat bran (WB). GOC was found to be the best producer of the enzyme among these. Combination of WB and GOC (1:1) resulted higher enzyme titres than the individual substrates. Maximum amount of enzyme (9196 U/gds) was obtained when SSF was carried out using WB + GOC, having initial moisture of 64% and supplemented with lactose and ammonium nitrate (1% each) at 30ºC for 72h using 2 mL spore suspension (6x10(7)spores/ml). Partial purification of the enzyme using ammonium sulphate fractionation resulted in 2.4-fold increase in the activity. The enzyme showed molecular weight of 68 KDa by SDS-PAGE. Except Mn, all other metal ions such as Ca, K, Na, Mg were found to be inhibitory for the enzyme activity. The enzyme was optimally active at 50(0)C and pH 5.0.