Production of β-galactosidase by Aspergillus oryzae in solid-state fermentation

Abstract

Fungal culture exhibiting β-galactosidase activity was isolated and identified asAspergillus oryzae from soil polluted with milk dairy factory effluents. Optimization of β-galactosidase (E.C 3.2.1.23) was carried out in Solid State Fermentation (SSF). Wheat bran and rice husk supports the maximal growth and β-galactosidase production by A.oryzae. The fungal culture utilized several carbon sources for the β-galactosidase induction. Glucose serves as a best carbon source, followed by lactose, maltose and sucrose. Among the various nitrogen sources used in this study, sodium nitrate found to be the best. Certain fermentation parameters involving initial pH, moisture content and incubation temperature were studied separately. Maximal amount of β-galactosidase activity and protein content was obtained when SSF was carried out using wheat bran and rice husk in 1:1 ratio, having initial moisture of 90%, initial pH 5.0 and supplemented with (12.5%) w/w glucose and 1% w/w sodium nitrate at 30oC for 7 days using 10 ml spore suspension (1 x 107 spores/ml) as inoculum’s size. Key words: Aspergillus oryzae, β-galactosidase, solid state fermentation.