Produção de enzimas fúngicas em biorreator para degradação de material lignocelulósico e atrazina

Abstract

Agroindustry is an important economic activity that, in addition to generating jobs, guarantees food production and Brazilian participation in the foreign market. Agroindustry, although important, is related to the use of agricultural inputs that, when used improperly along with the waste generated by agricultural activity, negatively impact the environment. To minimize these impacts, bioremediation strategies using microorganisms have been made to add value to agricultural waste and convert contaminating compounds into less toxic products. Therefore, the objective of this work was to produce ligninolytic enzymes of filamentous fungi through solid-state fermentation using an alternative carbon source and to evaluate their efficiency in the degradation of sugarcane bagasse and atrazine. Laccase production was evaluated by Penicillium brevicompactum CCDCA 11400 on a low scale and the scale-up of enzymatic production in column bioreactor at times 0, 7 and 14 days, at 19 ° C and 23 ° C and pH 4 and 7. Degradation of sugarcane bagasse was evaluated in six different assays: control, pure enzyme, inoculum of P. brevicompactum CCDCA 11400 (pH 4), crude extract (pH 4), crude extract (pH 7) and inoculum of P. brevicompactum CCDCA 11400 (pH 7). An analysis of High-Performance Liquid Chromatography (HPLC) was performed to quantify carbohydrates: arabinose, glucose, xylose, cellobiose, organic acids: glucuronic acid, formic acid and acetic acid and also furfural and hydroxymethylfurfural. The greatest enzymatic activities were corrected on a small scale at pH 4 to 19 ° C after 14 days of fermentation, with the highest value equal to 1801 U/L. In the bioreactor, the highest value of laccase activity was also found at 19 ° C, but at pH 7, in the amount of 965.5 U/L. Regarding the degradation of sugarcane bagasse, the best results were obtained when combined with atrazine, especially when using the inoculum of P. brevicompactum CCDCA 11400, where about 40% of the substrate was degraded, possibly promoted by enzymatic activity, which also was greater in these conditions. The concentrations of glucose, xylose and acetic acid obtained showed that hemicellulose was depolymerized and that, probably, during fermentation, sugarcane bagasse was the target of attack by other lignocellulolytic enzymes besides laccase. Considering the fact that furfural and hydroxymethylfurfural are fermentation inhibitor compounds, the concentration achieved was too low to be able to prejudice the bioconversion of sugarcane bagasse. That said, the results obtained in the present study were satisfactory for the production and application of laccase of Penicillium brevicompactum CCDCA 11400, which prove the biotechnological potential of this species.