Influence of cultivation conditions on the production of a protease from Aspergillus carbonarius using submerged fermentation

Abstract

The ability of a raw starch digesting amylase producer, Aspergillus carbonarius for protease production was evaluated in this study using standard methods. The fungus grew and produced appreciable levels of protease using different carbon and nitrogen sources. Sources of carbon and nitrogen significantly (p < 0.001) influenced protease production by this fungus. Soybean meal and glucose were the best nitrogen and carbon sources, respectively for the production of protease by A. carbonarius. Maximum protease production was achieved with 5% glucose and 5% soybean meal in combination with 0.1% peptone (as carbon and nitrogen sources, respectively), 0.04% FeSO4, 0.1% NaCl, 0.1% (v/v) Tween 80 and initial pH 6.0. Time course of enzyme synthesis by the fungus showed that the enzyme production occurred through the logarithmic to stationary growth phases with maximum enzyme yield being obtained on the 9th day of fermentation corresponding to the final culture pH of 4.6. The results suggested the potential secretion of protease by A. carbonarius using cheaper and locally available substrates as carbon and nitrogen sources and its subsequent application in various industries. Key words: Aspergillus carbonarius, glucose, soybean and peptone, protease, production.