Resumo

Lignocellulosic residues from agriculture and forestry have potential as cheap and renewable feedstocks for large-scale production of fuels and chemicals. The biodegradation of cellulose to soluble sugar is a process which is only possible after the action of complex cellulolytic pools produced by cellulolytic microorganisms. Filamentous fungi, typically Trichoderma and Aspergillus species, are the main source for industrial cellulase preparations. Significant research efforts have been invested in evaluating and understanding the enzymatic hydrolysis of lignocellulosic substrates by cellulases and xylanases produced by species of Trichoderma sp. In previous studies, we isolate cellulose-degrading Trichoderma harzianum IS-05 strain from Sandy Coastal Plains of Northeast Brazil and tested for cellulases and endoxylanases production under submerged fermentation using wheat bran 4.0% (w/v) and peptone 0.25% (w/v). The system was incubated under agitation (180 rpm) at 30ºC, for 4 days. The crude enzyme preparation was obtained after filtration and centrifugation and the enzymatic assays were performed (FPase, CMCase and Xylanase activities). Preliminary studies for the temperature and pH activity profile and effect of metal ions on enzyme activity were performed. The results showed the maximal enzyme activity at 3rd day-fermentation for FPase (1.06 U/mL) and endoxylanase (371.28 U/mL) and 4th day for CMCase (1.67 U/mL). The temperature profile showed optimal at 50ºC for FPase and endoxylanase activity and 60ºC for CMCase activity. The pH profile showed optimal at 6.0 for FPase and endoxylanase activity and 9.0 for CMCase activity. None of metal ions tested showed a positive effect on enzymes activities. The incubation of crude enzyme extract with steam explosion pre-treated sugarcane bagasse for 24 hours at 50ºC generated 18.52 g/L of reducing sugar. The results obtained indicate that crude enzyme preparation from Trichoderma harzianum IS-05 containing good levels of CMCase, FPase and Xylanase and the biochemical characteristics observed suggesting a good profile for biotechnological applications.