Cellulase production by Brazilian Trichoderma spp. for sugarcane bagasse saccharification

Agro-industrial cellulosic residues can be converted into ethanol. To convert cellulose into fermentable sugars, cellulases have a fundamental role. In this work, we evaluated the production of cellulases by 7 strains of Trichoderma spp. isolated from agricultural soils. We used the medium proposed by Mandels and Weber (1969) with 1% of elephant grass as carbon source. Each fungus (1x10⁶ spores/mL) was inoculated in five Erlenmeyer flasks containing 100 mL of culture medium and flasks were incubated for 120 h at 28 °C and 150 rpm. The fungal supernatant was lyophilized and resuspended in deionized water in a mass/volume ratio of 1/10. Optimal pH and temperature of FPase activity of each fungal extract was determined using a Central Composite Rotatable Design (CCRD). Tested temperatures ranged from 30 to 70 °C and pH from 3 to 8. The model was validated and the optimal temperatures and pH obtained for each extract were used for saccharification experiments of sugarcane bagasse. Pretreatment of sugarcane bagasse was hydrothermal followed by alkaline treatment, which yielded a biomass with 73.92% of cellulose. The experiments of pretreated sugarcane bagasse saccharification were performed in 50 mL Erlenmeyer flasks, with 5% biomass, 8 FPU/g of biomass and agitation of 200 rpm. After 24 hours hydrolysis, the highest conversion of cellulose into glucose was obtained with the extract CCMA 1208 (42.5 ± 1.6%). These results are promising for industrially relevant applications, and CCMA 1208 cellulase activity may be further improved both by a classical genetics approach as well as genetic engineering.