Seleção e avaliação da produção de tanase por fungos filamentosos em fermentação submersa utilizando resíduos agrícolas

Abstract

Tannins are water-soluble polyphenols, derived from the secondary metabolism of plants. They are classified into condensates and hydrolysables, the latter of which can be converted into gallic acid and glucose by the action of the enzyme tanase that acts on the esters and lateral bonds of its molecules. The enzyme tanase is produced in the presence of the tannic acid inducer, which is still little explored due to the high cost of its production. Thus, it is interesting to select microorganisms that produce a large amount of this enzyme, as well as the use of low cost substrates for their production. Therefore, the objective of the present study was to isolate and select filamentous fungi present in the banana plant (Musa sp.) As to their capacity to produce tannins and to evaluate the production of this enzyme under different cultivation conditions. Forty fungi were isolated, among which 8 stood out for producing tannase in a solid medium containing tannic acid as the sole carbon source. These were evaluated in submerged fermentation, in which the Aspergillus sp. PS2.02 stood out with an activity of 13.20 ± 1.61 U/mL. After optimization tests using agro-industrial residues, salts, tannic acid, temperature and production time, the maximum activity found was 20.43 ± 0.43 U/mL, in a medium containing banana peel and 3% tannic acid in the period 5 days of fermentation at 30 ᵒC. The results are promising, since the Aspergillus sp. PS2.02 showed a high production of tannase in medium containing only the enzyme inducer, water and banana peel, a widely available agricultural residue that can be used to reduce the costs of producing this enzyme.