BIOPROSPECÇÃO DE FUNGOS ISOLADOS DE REMANESCENTES DE FLORESTA OMBRÓFILA MISTA PRODUTORES DE -GLICOSIDASES: POTENCIAL CELULOLÍTICO DE Aspergillus flavus

Abstract

In recent years the growing interest in obtaining fungal enzymes in industrial processes. The bioprospection of microorganisms with potential enzymatic has been the subject of several studies. Among the enzymes of biotechnological interest, β-glucosidases, are widely studied due to their numerous economic applications, such as in the pulp and paper, animal feed, food and textile industries, among others. The objective of this work was to isolate several fungal strains, as well as to evaluate their potential for β-glycosidases production. Filamentous fungi were isolated from the soil of the Botanical Garden of Faxinal do Céu and Salto São Francisco Park, both areas of the Mixed Ombrophylous Forest, located in the CenterSouth region of the state of Paraná. In addition, the objective of this study was to investigate the effects of several physicochemical parameters on the production of β-glucosidases by the best selected strain line, using eucalyptus peel as an alternative substrate. In addition, the enzymes produced were biochemically characterized. During the optimization process of the β-glucosidases production, the Rotational Compound Central Design applicable to the Response Surface Methodology was used as a statistical tool. Among the 67 strains isolated from two distinct FOM fragments, the fungus Aspergillus flavus was the one that presented the best levels of βglucosidic enzyme production when cultivated in the presence of eucalyptus bark. Maximum production levels were reached when the substrate concentration was of 2.0% of substrate, culture pH of 5.5, culture time of 10 days and agitation of 100 rpm, corresponding to a yield of 5.20 U ML-1. The β-glucosides produced were more active at 5.5 ° C, pH 4.5, remaining stable at 50 ° C and pH 6.0. When evaluating the effect of several substances on β-glucosidases activity, the enzyme was notably activated by 10 mM β-mercaptoethanol followed by NH 4 Cl and CaCl 2, but considerably inhibited in the presence of the detergent SDS and EDTA. The eucalyptus bark proved to be a promising substrate for the production of βglucosidases as a low-cost residue produced in large quantities. The fungus Aspergillus flavus showed potential for the production of these enzymes, which have desirable properties for certain industrial applications.