Quantification of Biomass and Phytase Production for Solid-state Fermentation with Aspergilltis niger on Wheat Bran

Phytase is produced by Aspergillus niger both in liquid and solid-state fermentation. The kinetics and production of phytase in solid-state fermentation have not been well quantified. This research focussed on experimentally determining how Aspergillus niger growth and phytase activity production are related to environmental temperature and initial moisture content over time. Solid-state fermentation of Aspergillus niger on wheat bran and soybean meal were conducted at three temperatures (25, 30, and 35°C) and three initial moisture contents (50, 55, and 60 % wet basis) in a split-plot full factorial experimental design. Fermentations were conducted for 0, 24, 48, 72, and 120 hours. Temperature affected phytase activity production, but substrate initial moisture content did not. The optimal fermentation treatment for maximum phytase activity production was 30°C, 55-60 % water content and 72 hours of fermentation (≡ 700 U/g substrate). The production of phytase activity was predicted well (R² of 0.90) by glucosamine measurements. For 72 hours of fermentation, phytase production was related linearly to glucosamine production and the linear parameter was 6742.4 (U · ml solution)/(g substrate · mg glucosamine).