Characterization and potential industrial application of enzymatic extracts from pacu (Piaractus mesopotamicus)

Abstract

Fish production can generate considerable amounts of waste, whose inadequate final disposition could cause environmental damage. The use of these wastes to obtain high value-added products of industrial relevance is an alternative for sustainable aquaculture production. In this study, acidic extracts rich in pepsin-like enzymes (EP) and alkaline extracts rich in trypsin-like enzymes (ET) were obtained and characterized from the viscera of pacu (Piaractus mesopotamicus), evaluating their potential biotechnological applications. EP and ET showed maximum catalytic activity at pH 2 - 45°C and pH 7 - 45°C, respectively. They were stable in pH ranges of 1.0 to 3.5 and 7.5 to 10.5 and temperature ranges of 0 to 37°C and 0 to 45°C, respectively. The activity of EP was inhibited by pepstatin A, but not by PMSF and SBTI. EDTA and SDS caused partial inhibition, confirming the presence of pepsin-like enzymes. ET was inactivated in the presence of SBTI but not by SDS. PMSF and EDTA decreased the activity by 50%, confirming the presence of trypsin-like enzymes. Divalent ions (Ca2+ and Mg2+) did not alter the proteolytic capacity of the extracts, but it decreased with increasing NaCl concentration. Moreover, ET and EP were effective in hydrolyzing the silver-impregnated gelatin coating of discarded x-ray films and generating F(ab’)2 fragments from equine IgG degradation, respectively. In conclusion, these extracts could be applicable in processes requiring maximum activity at moderate temperatures and low NaCl concentrations, in the recovery of metallic silver and PET sheet from used x-ray films and in the production of biological products. These results open up new perspectives for the circular economy of pacú aquaculture farms.