Optimization of glucoamylase production by Aspergillus niger in solid-state fermentation.

Glucoamylase production by Aspergillus niger in solid-state fermentation was optimized using factorial design and response surface techniques. The variables evaluated were pH and bed thickness in tray, having as response enzyme production and productivity. The bed thickness in tray was the most significant variable for both responses. The highest values for glucoamylase production occurred using pH 4.5 and bed thickness in the inferior limits at 2.0-4.2 cm. For productivity, the optimal conditions were at pH 4.5 as well and bed thickness from 4.4 to 7.5 cm. The optimal conditions for glucoamylase production while obtaining high activity without loss of productivity were pH 4.5 and bed thickness in tray from 4.0 to 4.5 cm, which resulted in an enzyme production of 695 U/g and productivity of 5791 U/h.