Investigation of optimal parameters for aspartic protease production from Aspergillus terreus using solid-state fermentation

The current study presents extracellular Aspartic protease production using low-cost agro-industrial waste with the indigenously isolated novel strain Aspergillus terreus, and parameters that largely affect enzyme production, namely fermentation time, pH, moistening solution, temperature, inoculum volume, and different solutions, were utilized for enzyme extraction. The isolated fungus was identified as A. terreus (registered as A. terreus SFH5 in the gene bank) by phenotypic and molecular characterization, showed the highest aspartic protease activity of 258.6 units/mL and 272.2 units/mg using a solid-state fermentation technique during screening, and was further used for media component screening and optimization studies. The study employed wheat bran as the preferred production medium and casein as the nitrogen source. The fermentation process was conducted at a temperature of 30°C and a pH of 5. The moistening solution to fermentation medium ratio was set at 3:1, while an inoculum volume of 2 mL (containing 1 × 106 spores/10 g solid) was used. Distilled water was selected as the most effective solution for extracting the enzyme. It has been discovered that the locally isolated novel strain of A. terreus, SFH5, can efficiently produce a substantial amount of aspartic protease by utilizing agro-industrial waste. This makes it a viable candidate for large-scale optimized production of the enzyme to satisfy industrial requirements.