Avaliação da atividade enzimática de frutosiltransferase produzida por aspergillus oryzae em fermentação semi-sólida de resíduos de melão cantaloupe

Abstract

Waste generation is inherent to any activity of the production sector, and these materials represent an economically viable alternative to be used as substrate for bioprocess for the production of enzymes and other value-added products. Having the aim of reusing food waste as substrate for enzyme production, this study evaluated the production of fructosyltransferase (FTase) by Solid-State Fermentation using melon peel, whole and defatted melon seeds residues as substrate and Aspergillus oryzae as producer strain. A kinetic study was carried out in BOD using cultivation medium containing 5g of dehydrated melon peel, whole melon seeds and defatted melon seeds supplemented with sucrose and fructose solutions and other nutrition factors. The fermentations were carried out in shake flasks during 7 days at 45°C. The moisture was kept at 60%, water activity was 0.9, pH was 5.5, for the media containing melon peels, and 6.0 for the media containing whole and defatted melon seeds. After each 24 hours, a sample was taken, the material was filtered and centrifuged to obtain an extract, which was further evaluated for its hydrolytic activity by Dinitrosalicylic acid method having sucrose as substrate. Results showed that maximum extracellular fructosyltransferase production by hydrolytic activity was reached at 144 hours of fermentation having melon peel as substrate (90.78 U/g). The media containing whole melon seeds showed values of activity 45.1% lower, reaching a maximum of 49.82 U/g in 24 hours of fermentation. The media containing defatted melon seeds reached a maximum activity of 0,635 U/g. An HPLC run showed that the highest FTase activities were observed in the media that contained melon peel residue (1,14 UI/g in 72 h). The highest FTase activity observed for the media that contained melon seeds residues was reached at 48 h (0,76 UI/g) and the highest FOS concentration was 1,90 mg/mL, in this same media composition and at the time of 48 h. These results show the potential of using melon peels and whole melon seeds as substrate for isolation and evaluation of specific types of hydrolases such as fructosyltransferases, the class of enzymes responsible for catalyzing hydrolytic and transfructosylating reactions.