Production of mannanase enzyme by some local fungal strains and biomass utilization for the removal of some heavy metals from aqueous solutions

Abstract

Abstract In the present study forty locally fungal isolates were tested for their abilities to produce β-mannanase in both static and shaking cultures. The fungus Aspergillus tamarii NRC3 was found to be the most potent producer for β-mannanase and therefore it was used throughout this study. The favorable cultural conditions for Aspergillus tamarii NRC3 β-mannanase production found to be; locust bean gum (1%), sodium nitrate (0.2%), inoculum age (6 days), inoculum size (one disk, 4 mm diameter, equal 2x107spores/ml), production medium volume (50ml), 7 days of static incubation, pH 5.0 , 25 ºC and no effect of surfactants as tween 20, 80 and SDS on β-mannanase production was detected. The agarose (3%) was the best matrix at entrapment cell immobilization technique, where gave a powerful effectiveness factor (1.01 Cimmo/Cfree). Acetone fractional precipitation of the crude enzyme at 25-50% concentration was the successful partial purification of Aspergillus tamarii NRC3 β-mannanase and exhibited the highest recovered activity (37.25u/mg). The enzyme was completely purified by ion-exchange chromatography (DEAE-cellulose column) and gel filtration chromatography (Sephadex G-100 column) with 4.97 purification fold and 15.46% enzyme recovery.