Tuesday, May 3, 2011
The biodiversity of Brazil is one of the most abundant of Earth. However, there are still few reports about the biodiversity of microorganisms from the Brazilian cerrado (savanna) biome. The project "bioprospection of filamentous fungi of cerrado" search in different physiognomy (riverbank forest, savanna like cherubs, density-forest, others) filamentous fungi with biotechnological potential. From the cerrado samples were isolated 225 fungi from soil, litter and logs in decomposition. The fungi isolation was carried out in selective media (Agar-Oats, DG18 and Rose Bengal) at temperatures of 28, 38 and 45°C. These isolates were preserved in medium containing 18% glycerol and pure mineral oil at room temperature and also in crypreservation with 50% glycerol at -80°C. The isolates were cultured in liquid medium with lignocellulosic wastes, including sugar cane bagasse (SCB), banana stem (BS) and dirty-cotton residues (DCR) as carbon sources in order to determine the potential for production of holocellulases. Some fungi (Aspergillus foetidus, A. flavus, Penicillium citrinum, P. roqueforti, P. fellutanum, P. rugulosum and Fusarium solani) were identified by morphological techniques. The xylanase activity was more relevant from the isolates grown at 28 and 38°C. In addition, these fungus samples also showed expressive values of endoglucanase activity. A. foetidus showed the best yield of xylanase and mannanase activities (0.810 and 0.280 UI.mL-1, respectively) when grown in BS, while the highest endoglucanase activity (0.269 UI.mL-1) was obtained in a medium containing SCB. The results show a biodiversity of fungi species from the cerrado with the potential for the production of holocellulases.