Study of the growth of A. casiellus in conventional soybean meal for enzyme production

Abstract

Soybean meal is one of the major wastes from the Brazilian agribusiness, in view of the large domestic production of grain. This byproduct has characteristics that make it interesting to be used as substrate in the process of solid-state fermentation (SSF). Although it is not much used industrially as the submerged fermentation (SmF), it may be a viable alternative, as it has shown superior results of productivity, specially in the cultivation of filamentous fungi and the production of enzymes. The present study aimed the production of the enzymes protease, amylase and invertase by SSF using conventional soybean meal and the fungus A. casiellus. The pH and nutrient sources were evaluated and, finally, an optimization of the parameters of the SSF through experimental design and construction of growth curves of the fungus were carried out. The optimization of the invertase production process reached the best values for specific enzymatic activity (AEesp) at neutral pH (6.7) and 3% additional source of nitrogen to the medium, with initial moisture of 50% and temperature of 28oC. The best result for the protease activity was obtained in the evaluation of medium nutrient sources, with the use of 2% of carbon and nitrogen sources and 2% of mineral sources. Already, amylase did not show significant results for the variables used.

Key words: SSF, soybean meal, A. casiellus.