Economic utilization of agro-industrial wastes through solid state fermentation by aspergillus niger f-21 for alpha-amylase production

ABSTRACT

Solid state fermentation technique was carried out in utilization of various agro-industrial wastes from different industries for the production of fungal alpha-amylase [E.C. 3.2.1.1] by locally isolated strain of Aspergillus niger. Culture conditions affect enzyme formation such as incubation time, initial pH, moisture level, moistening agent and nitrogen source were investigated. High level of enzyme activity could be obtained after 48 hr using potato peels as a substrate with initial pH 6.0 using whey permeate level of 50% as a moistening agent and urea as a cheap nitrogen source at level 400 mg N/1 moistening agent. The obtained enzyme has an activity of 620 U/g fermented substrate. The obtained enzyme was stable in a wide range of pH between 3-9 as well as the enzyme proceeds through wide range of temperature ranged between 50-85C. The enzyme looses only about 10% from its optimal activity between 90-100C and at 105C the relative activity was about 27%. The crude enzyme was heat stable when incubated at 70C for 39 hr retaining its maximum activity. Crude enzyme was applied for potato starch digestion using different slurries concentrations up to 30% giving about 96% digestion