Screening of Aspergilli and their cellulolytic properties

Nine hundred seventy Aspergilli strains were isolated from cellulosic wastes and twenty four strains were screened as cellulolytic and identified as Aspergillus tubengensis, A. niger, A. ficuum, A. awamori str. 1&2, A. foetidus, A. japonicus str.1&2, A. aculeatus str.1&2, A. flavus str.1,2,3 and 4, A. clavatoflavus, A. parasiticus, A. oryzae, A. spersus, A. fumigatus, A. cervinus, A. ochraceus, A. crustosus, A. terreus and A. cremeus. Among them A. oryzae showed the highest reducing sugar level and cellulase activity. The optimum pH, temperature and Km value of crude enzymes were 5.5, 50°C and 0.27%, respectively. The specific activity of purified extra and intracellular enzyme was 64.17 and 43.9 mg/ml although the increase of purification fold was about 53 and 41, respectively. The molecular weight was estimated to be 41,500 and 38,600 by gel filtration and 41,000 and 38,000 by SDS-PAGE. The enzymes gave single band and showed absorption spectra about 260-290 and 240-270 nm and Km value was 0.67% and 0.83%. The activities of the enzymes were increased in presence of Ca2+ , Mn2+ and Mg2+ but completely inhibited by 0.5M EDTA and significantly inhibited by Cu2+, Hg2+ and Fe3+.