Produção de enzimas celulolíticas e hemicelulolíticas por fermentação sólida e fermentação submersa em fibra de sisal (Agave sisalana) utilizando Trichoderma reesei.

Abstract

The widespread use of cellulolytic and hemicellulolytic enzymes in some processes has been limited by their high cost, therefore studies have been developed with the objective of producing these enzymes through the solid state (SSF) and submerged (SmF) fermentation process from lignocellulosic agroindustrial residues, thus reducing enzyme production costs and adding value to the residue. Thus, the objective of this work was to evaluate the enzymatic production of cellulolytic and hemicellulolytic enzymes by the filamentous fungus Trichoderma reesei by solid and submerged fermentation using sisal fiber as substrate. The characterization of sisal fiber was performed with the objective of to know its composition. Solid state and submerged fermentation was performed using the Trichoderma reesei microorganism at a concentration of 107 spores/g or mL at a temperature of 28 °C. Cellulase (CMCase, FPase and β-glycosidase) and hemicellulase (Endo-β-1,4-xylanase) enzymes were studied using experimental design 22 with 3 central points and kinetic monitoring of production for 240 h, analyzing the influence of humidity and wheat bran content on enzyme production in solid fermentation, and the ratio m/v and wheat bran content in submerged fermentation. The characterization showed that this substrate has potential to be used in the production of cellulolytic and hemicellulolytic enzymes, mainly because it presented a satisfactory percentage of alfacellulose (58.40%) and hemicellulose (15.21%), which are inducers of these enzymes and acid pH (4.35) ideal for the production of enzymes in solid and submerged fermentation with fungi. The statistical treatment of the designs at a significance level of 95% showed that in the SSF the initial humidity and wheat bran contents influenced the enzymatic activity of the enzymes CMCase, FPase, xylanase and β-glycosidase, and in the FSm the variables of wheat bran and mass/volume ratio (m/v) of substrate concentration also influenced the enzymatic activity of the enzymes of the enzymes CMCase, xylanase and β-glycosidase. In the SSF, the assay carried out with 60% humidity and 50% wheat bran in the substrate composition showed the highest enzymatic activity for all studied enzymes. CMCase enzyme showed maximum activity of 0.46 U/mL, FPase enzyme showed maximum activity of 0.07 U/mL, xylanase enzyme showed maximum activity of 78.96 U/mL and β-glycosidase enzyme showed maximum activity of 13.88 U/mL. In SmF, the assay with 5% of substrate concentration and 50% of wheat bran presented the highest enzymatic activity for all enzymes studied. The CMCase enzyme showed a maximum activity of 0.28 U/mL, the xylanase enzyme presented a maximum activity of 78.34 U/mL and the enzyme β-glycosidase showed a maximum activity of 9.47 U/mL. Given the fermentations used, SSF obtained the best results when compared to SmF for the production of CMCase, xylanase and β- glycosidase enzymes.