Otimização da produção de celulases por Yarrowia divulgata isolada de coco tucum

Abstract

Cellulose is the most abundant organic and renewable biomass, considered a good alternative for the production of chemical products and biofuel. The conversion of this polymer into fermentable sugar requires synergetic action from enzymes inside the cellulolytic complex. This study aims to evaluate the influence of the variables pH, temperature, MgSO4, MnSO4, glucose, lactose, cellobiose and arabinose in the production of cellulases in submersed cultivation of a lineage of Yarrowia divulgata, using a Plackett-Burman (PB) delimitation design. The amount of enzymatic activity varied from 0 to 0,105 U/mL for endoglucanase, from 0,096 to 0,291 U/mL for exoglucanase, from 0 to 0,125 U/mL for total cellulase and from 0 to 0,308 U/mL for β-glucosidase. The results show that the significant variables were MgSO4 (endoglucanase), arabinose (exoglucanase), MnSO4 and pH (total cellulase), there was no significant influence of the variables for the production of β-glucosidase. Based on the results from the PB design, a complete RCCD (Rotable Central Composite Design) (22 ) outline was done using MgSO4 and arabinose variables, which results showed that the amount of endoglucanase activity varied from 0 to 0,295 U/mL, for exoglucanase the activity varied from 0 to 0,234 U/mL, for total cellulose from 0 to 0,337 U/mL, for β-glucosidase from 0 to 1,184 U/mL and the statistical analysis showed that arabinose presented significant influence for exoglucanase and β-glucosidase. Based on the generated models, the concentration of arabinose that would induce the most activity was 1g for exoglucanase and of 10g for β-glucosidase. The validation trials using these arabinose concentrations showed that a significant RAISE of activity occurred varying from 0,141 to 0,355 U/mL for exoglucanase and from 0,954 to 0,964 U/mL for β-glucosidase. Two independent RCCDs were performed to evaluate the enzymatic extracts provenient from cultivations with 1g and 10g of arabinoses. The optimal pH and temperature for the enzymatic reaction obtained for β-glucosidase were 5 and 35°C (crude extract derived from cultivation with 1g of arabinose) and of 5.71 and 47.1°C (crude extract derived from cultivation with 10g of arabinose). For the exoglucanase enzyme, the optimal pH was pH 6.0 (crude extract derived from cultivation with 1g of arabinose) and there was not a significant influence of temperature (for both 1g and 10g of arabinose). For endoglucanase and total cellulose, there was not a significant influence of pH or temperature in the enzymatic reaction. The Y. divulgata lineage showed potential to produce cellulolytic enzymes.