An optimization approach to the bioconversion of flour mill waste to α-amylase enzyme by Aspergillus oryzae

BRAIA, MAURICIO; CABEZUDO, IGNACIO; BARRERA, VIRGINIA LIS; ANSELMI, PABLO; MEINI, MARÍA-ROCÍO; ROMANINI, DIANA

PROCESS BIOCHEMISTRY - (Print)

ELSEVIER SCI LTD

Año: 2021 vol. 111 p. 102 - 108

1359-5113

Alpha-amylase is one of the most employed enzymes in the food industry because of itscapacity to degrade starch, improving the organoleptic and nutritional properties of foodproducts. Thus, it is very important to develop novel industrial production processes for itsproduction. A submerged fermentation process using Aspergillus oryzae was optimized tomodulate the most important factors affecting alpha-amylase production. Flour mill waste, anabundant worldwide agro-industrial residue, was used as substrate due to its starch-richcomposition. This residue was able to avoid catabolite repression during the fermentation,acting as a slow-release substrate. The process optimization led to a maximum yield of alpha amylase production of 14076 ± 2346 U/L. The secretome of the fungi in the tested conditionswas analysed by LC-MS, showing that two isoforms of alpha-amylase (amy-1 and amy-3) wereproduced. Finally, a two-step process was developed to purify alpha-amylase, consisting of fractional precipitation using (NH4)2SO4 followed by hydrophobic interaction chromatography.The purification allowed a four-time concentration of alpha-amylase, with an eleven-timepurification factor and 65 % recovery and a reduction of the proteolytic activity to 14%.