Resumo

Xylanases, a group of hemicellulolytic enzymes, are required for the hydrolyisis of β1,4-xylans present in lignocellulosic materials. The high cost of production of these enzymes, however, has hindered the industrial applications of xylan bioconversion. Various Trichoderma sp. has ability in extracellular enzymes produced. The aim of present study was to evaluate the influence of cultive conditions different on production of xylanase by T. virens. The strain was cultivated using by SSF condition in a mixture 5g (1:1) sugarcane bagasse (SCB) and wheat bran (WB) or sugarcane straw (SCS) and wheat bran (WB). Conidia or mycelial biomass of cultures with 4 days growth were suspended in sterile water and added sterile nutrient solution Urea (0.3 or 0.7%), pH of 5 or 7. The trials were carried out at 28°C for 48 and 192 hours. Among the factors used the average greatest of xylanase was obtained with 0.7% of nutrient solution (132 U/g), pH 7 (123 U/g) and 48h of incubation time (202 U/g). However, at 0.3% Urea (103 U/g), pH5 (113 U/g) and 192h incubation (33 U/g), induced the lower xylanase activity. The tests with the two types of substrates showed no significant difference in production, with values of 99 U / g with cane straw and 97 U / g for bagasse. The pH has a direct influence on the growth of microorganisms carrying out fermentation process. Low values may induce the production of secondary metabolites which interfere in the enzymatic production. Similarly, other studies with different strains Trichoderma, such T. reesei SAF3, T. harzianum MTCC 4358, and T. viride observed that production xylanase was better in a shorter fermentation time. The decline production may be due to the depletion of macro and micronutrients in the fermentation medium with the lapse in time, which stressed the fungal physiology resulting in the inactivation of secretary machinery of the enzymes. The short time incubation offers significant advantages such as; reducing the risk of contamination and decrease costs of enzyme production. The strain studied has good potential for xylanase production. Other tests with different conduction of culture will be further investigated during these studies to determine the best condition for production and application of enzymes.