Production of a protease inhibitor from edible mushroom Agaricus bisporus and its statistical optimization by response surface methodology.

The production of a protease inhibitor from Agaricus bisporus through solid-state fermentation was studied. The purpose was to produce protease inhibitor from natural, cheap, and readily available carbon and nitrogen sources. Solid-state fermentation enhanced the mycelia growth and also gave a higher yield of the product. Further, fungal growth and other production parameters were statistically optimized. The specificity of the inhibitor was tested and was effective against trypsin. Screening of significant factors (wheat bran, cyanobacterial biomass, initial pH, temperature, incubation period, and moisture content and inoculum size) was performed using Plackett-Burman design. Central composite design was used to determine the optimized values of the significant variables which were found to be temperature (27.5°C), incubation time (156 hr), cyanobacterial biomass (1 g), and moisture content (50%) and gave a statistical yield of 980 PIU/g which was 25.6% higher than experimental yield (780 PIU/g). The inhibitor was purified by ammonium sulfate precipitation and diethylaminoethyl (DEAE) cellulose chromatography (yield 43.89% and 0.21%, respectively) and subjected to reversed-phase HPLC to validate its identity. Since protease inhibitors act against proteases, finding ample therapeutic roles; the isolated protease inhibitor from A. bisporus can also be a probable medicinal agent after its further characterization.