Kinetics of exoglucanase and endoglucanase produced by Aspergillus niger NRRL 567

In this study we reported for the first time kinetics of exoglucanase (EXG) and endoglucanase (EG) from Aspergillus niger NRRL 567. The optimum pH and temperature for crude EXG and EG was found to be 3.5 and 30°C respectively. Zn2+, Ca2+, Mn2+ and Co2+ enhanced the crude activity of EXG and EG whereas Mg2+, Fe2+ and Hg2+ showed various degree of inhibitory effects. Cu2+ enhanced crude EXG activity and inhibited crude EG activity. The energy of activation (Ea) for the EXG and EG were 21.20 and 22.52 kJ mol-1, respectively. The Q10 values obtained for the EXG and EG were 1.38 and 1.4, respectively. These enzymes had lower Km value that shows their high affinity for the substrates. Overall, the studies demonstrate that these enzymes may be suitable for industrial use.Key words: Exoglucanase, endoglucanase, kinetics, characterization, Aspergillus niger NRRL 567

Corn stover-enhanced cellulase production by Aspergillus niger NRRL 567

The production of extracellular cellulases by Aspergilus niger NRRL 567 on corn stover was studied in liquid state fermentation. In this study, three cellulases, exoglucanase (EXG), endoglucanase (EG) and β-glucosidase (BGL) were produced by A. niger NRRL 567. The optimal pH, temperature and incubation time for cellulases production was found to be 3.5, 30°C and 96 h, respectively. Maximal cellulases activities were achieved with 4% corn stover, 0.1% molasses and 1% yeast sludge. To our knowledge, this is the first report on production of cellulases by using corn stover as a substrate from A. niger NRRL 567.Key words: Corn stover, yeast sludge, cellulases, Aspergi l lus niger