Sunday, April 29, 2007

Cellulase production by fungi Aspergillus terreus using agricultural residues

Mallú S. L. Queiroz1, Felipe M. Knopp1, Leda M. Gottschalk1, and Elba P. S. Bon2. (1) Biochemistry, Federal University of Rio de Janeiro, Cidade Universitária CT, Bloco A, Ilha do Fundão, Rio de Janeiro, Brazil, (2) Chemistry Institute, Federal University of Rio de Janeiro, Cidade Universitária, CT, Bloco A, sala 539, Ilha do Fundão, Rio de Janeiro, Brazil

Cellulases, produced by fungi and bacteria, are responsible for the bioconversion of cellulose to soluble sugars and glucose. Amongst microorganisms that produce cellulases, fungi are probably the most efficient, for possessing very active extracellular complex, such as Trichoderma and Aspergillus. However, Aspergillus produces higher levels of b-glicosidase that hydrolyze cellobiose in two glucose molecules. The objective of this present work was to study the cellulolytics enzyme production for two A. terreus strains being used agricultural residues as carbon source. Cultivation was performed using corn steep liquor 1,2% (v/v) as nitrogen source and as carbon sources in 3% concentration (p/v) wheat bran, sugar cane bagasse, dried distillers grains, glucose and lactose. Enzyme production was performed in shake flask experiment at 30°C and 200 rpm. The determination of the activities of endoglucanase, exoglucanase and b-glicosidase had been carried through in the supernatant of the fermentations using the methodologies described standard by IUPAC (Ghose, 1987). The medium containing wheat bran as carbon source obtained high levels of endoglucanase activity compared to another carbon sources.