Xilanases de Trichoderma piluliferum e Trichoderma viride: produção, caracterização bioquímica e aplicações industriais

Abstract

The need for the use of enzyme technology for bioconversion of lignocellulosic compounds boosts researches to cheapen and facilitate the development of several biotechnological products and services. Solid State Cultivation of microorganisms is a low-cost alternative that allows us to use agro-industrial by-products as a substrate for the enzymes production. In this study we investigated the xylanase, enzyme of the hemicellulolytic complex which assist the degradation of plant cell wall. We aimed to optimize the production of xylanase by solid state cultivation by two strains of Trichoderma spp. isolated from the Pantanal/MS, the characterization of the enzymes produced was investigated and we evaluated its potential for use in cattle diets. The parameters of cultivation evaluated was: the use of different by-products as a substrate (wheat bran, soy bran, rice peel, sugarcane bagasse, corn straw and corn cob), initial moisture content of the medium (50-80%) and cultivation time (from 24 to 120 hours). The enzymes were characterized about the pH effect and temperature effect on its catalytic funtion. The extracts obtained from the optimization of culture parameters were evaluated for the catalytic potential. The fungus T. piluliferum had better production of xylanase enzyme, about 301.8 U g -1 (30.18 U mL -1 ), when grown on wheat bran, with 75% moisture for 96 hours. The optimum pH of the enzyme produced by T. piluliferum was 4.5, obtaining as the optimum temperature 50°C. The enzyme was stable at a pH range which ranged from 3.0 to 10,0 and it remained stable for 1 hour at 40°C. The best culture parameters for the cultivation of T. viride were: wheat bran as substrate, 65 and 70% initial moisture content and 48 hours cultivation. The xylanase produced by this fungus had 6.0 as pH optimum and 45°C as optimum temperature, the enzymes was stable at pH range which ranged from 3.0 to 10,0 keeping its activity after 1 hour at 40°C. Both enzyme extracts produced were effective in increasing feed digestibility of: Tifton Hay 185, sugarcane and corn silage. The use of xylanase enzymes produced in this work as feed additives for cattle can benefit animal nutrition. The xylanases present in the enzyme extract proved promising for production xilooligossacarídeos. The enzyme extracts showed low cellulase activity, which indicates potential for application in biobleaching processes of cellulose pulp in the pulp and paper industries.