Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
The Neurospora genome is predicted to contain twice as many cellulases as H. Jecorina. An analysis of the genomic data of N. crassa had identified seven copies of beta-glucosidase (bgl) genes including four copies of intracellular and three copies of extracellular beta-glucosidases. In this study, the multiple beta-glucosidase knockout strains were constructed. The regulation of cellulase in single and multiple beta-glucosidase knockout strains were investigated. The experimental data showed that only two copies of intracellular (gh1-1, gh3-6) and two copies of extracellular beta-glucosidases (gh3-3, gh3-4) had detectable activity when the N. crassa knockout strains grew on the avicel and rice straw. Among four copies of expressed beta-glucosidases, the extracellular beta-glucosidase gh3-3 dominated the bgl activity followed by gh3-4, gh3-6, and gh1-1. For two of the extracellular beta-glucosidase, gh3-3 proved to be a cell wall bounded enzyme while gh3-4 accounted for the supernatant activity of beta-glucosidase. The correlation of bgl deletion and cellulase expression had been analyzed by RT-PCR. It was observed that there was an increase of CBH (I) and CBH (II) expression level in the gh3-4 knockout strains while the other strains showed comparative levels with the wild type.
Key words: Neurospora crassa, beta-glucosidase, cellulase, gene expression, gene knockout strain