Characterization of α-amylase produced by the endophytic strain of Penicillium digitatum in solid state fermentation (SSF) and submerged fermentation (SMF)

Abstract

α-Amylases are enzymes responsible for breaking the α-1,4 bond in polysaccharides with three or more glucose units, occupying the second place in the most widely employed enzymes in industry in the world. The objective of this study was to compare the yields of α-amylase produced by the endophytic fungus, Penicillium digitatum, strain D1-FB, isolated from Baccharis dracunculifolia D.C. (Asteraceae), through the solid state fermentation (SSM) and submerged fermentation (SmF) processes, in addition to characterizing the produced enzyme. The two fermentations were conducted for 120 h, taking samples every 24 h to obtain the peaks of production. The enzymes were characterized according to their optimal pH and temperature for performance and stability regarding the incubation in the presence of ions, variations in pH and temperature. The maximum yield of the enzyme was observed with SSF, using rice bran as substrate after 72 h of fermentation, with 1,625 U/mL. The α-amylase had an optimal pH at 6.5 and optimal temperature at 37°C. All the ions resulted in a decrease in the activity of α- amylase in the concentration of 5 mM. The enzyme proved to be quite stable in a pH range of 6.0 to 7.5 and up to the temperature of 37°C, but it presented great drops in activity with temperatures above 45°C and in the presence of ions at the concentration of 5 mM.

Keywords: Penicillium digitatum, α-amylase, starch, enzymes, endophytic