Optimization of solid state fermentation medium to produce β-galactosidase by Aspergillus oryzae

Based on single factor test, the solid state fermentation (SSF) medium to produce β-galactosidase by Aspergillus oryzae GN-1 were optimized by L9 (33) orthogonal test. The results showed that the β-galactosidase activity of 156.04U/mL was obtained , when SSF was carried out using wheat bran and water in 1∶1 ratio , supplemented with 1.5% (w/w) ammonium sulfate, 0.4% (w/w) magnesium sulfate and 3% (w/w) sucrose at 30℃ for 6 days, which was about 8.3 times of the β-galactosidase activity acquired on the basic medium.