COMPARATIVE STUDIES ON PRODUCTION OF CELLULASES FROM THREE STRAINS OF ASPERGILLUS NIGER

Abstract

Three strains of Aspergillus niger were retrieved from culture collection of the Department of Microbiology, University of Karachi, Karachi, Pakistan and were studied for their ability to produce cellulases. Cultivation at different temperatures and in presence of various carbon sources revealed that all the three strains produced more amounts of endoglucanase, βglucosidase and filter-paperase activities at 35o C; carboxymethyl cellulose promotes the production of filter paperase and endoglucanase activities whereas salicin induced β-glucosidase activity. Experiments on growth and enzyme production kinetics showed that generation time and hence volumetric rate of biomass production is influenced by the carbon source used in the medium; simple carbon source, such as glucose favored the growth of all the strains. Cellulases from all the strains showed optimum activity at temperature >50o C and under acidic range of pH, while melting temperature was 64- 65o C. These findings affirm that cellulases from A. niger are potential candidates as alternative to Trichoderma cellulases.