Production of beta-D-fructofuranosidases by Aspergillus sp. M2.4 and biochemical characterization

Abstract

Microbial enzymes, such as beta-D-fructofuranosidases that catalyze the hydrolysis of sucrose, are a clean alternative of catalysts for industries that manufacture better quality consumables, as they have a high degree of specificity, allow the regulation of activity and are synthesized under simple cultivation conditions. In this work, the production of invertases from the filamentous fungus Aspergillus sp. M2.4, as well as the biochemical characterization, since each process depends on specific parameters, and each microorganism synthesizes invertases with certain characteristics. To this end, filamentous fungi were isolated from decomposing organic matter, which were not good producers of invertase. Thus, four filamentous fungi from the laboratory's fungal bank were analyzed, selecting Aspergillus sp. M2.4, having as the best standards the growth in submerged culture medium Carvalho-Peixoto, for five days, at 30ºC, in a stationary way, using wheat bran as a carbon source, and yeast extract as a nitrogen source, as well as the CP medium salt solution itself, which provided an increase in activity from 35 total U to 290 total U, representing an 8-fold increase. In addition, the produced invertase showed an optimal point at pH 4.5 and 65ºC, which provided an increase in activity for more than 400 total U, about 12 times higher. It is worth mentioning that the enzyme showed good stability at pH, maintaining activity greater than 69% at pH 4.5 to 7.0, for 120 minutes, in addition to excellent thermostability, at temperatures from 50ºC to 55°C, with activity residual greater than 80%. These results suggest a possible industrial application of the invertase studied in bioprocesses, focusing on the reduction of sucrose crystallization in the production of ethanol from sugarcane and the synthesis of fructooligosaccharides.