Screening and Characterization of the High-Cellulase-Producing Strain Aspergillus glaucus XC9

Abstract

Cellulose is a kind of renewable resource that is abundant in nature. It can be degraded by microorganisms such as mildew. A mildew strain with high cellulase activity was isolated from mildewy maize cob and classified as Aspergillus glaucus XC9 by morphological and 18S rRNA gene sequence analyses. We studied the effects of nitrogen source, initial pH, temperature, incubation time, medium composition, and surfactants on cellulase production. Maximal activities of carboxymethylcellulase (6,812 U/g dry koji) and filter paperase (172 U/g dry koji) were obtained in conditions as follows: initial pH, 5.5 6.0; temperature, 30?C; cultivation period, 3  4 days; inoculum ratio, 6% (vol/vol); sugarcane bagasse/wheat bran ratio, 4:6. When bagasse was used as substrate and mixed with wet koji at a 1:1 (wt/wt) ratio, the yield of reducing sugars was 36.4%. The corresponding conversion rate of cellulose to reducing sugars went as high as 81.9%. The results suggest that A. glaucus XC9 is a preferred candidate for cellulase production.