The study involved the production of amylase from Aspergillus niger grown on yam peels in solid state fermentation. The process parameters: temperature, pH (initial) and incubation time were optimized for maximum amylase production using central composite design (CCD) of response surface methodology (RSM). Temperature was the most significant (p<0.05) parameter and the maximum interaction occurred between temperature and incubation time. The results of the study indicated that amylase is maximized (30.95 U/ml-min) at optimized levels of 49.53°C, 5.95 and 104 h for temperature, pH (initial) and incubation periods, respectively.

The increase in demand for local enzymes for industrial activities has stimulated the exploration of the extracellular enzymatic activities of several microorganisms. Using validated values from a central composite designed experiment, amylase from a locally isolated strain of Aspergillus niger was produced in a larger quantity by solid-state fermentation for characterization and its subsequent application in the hydrolysis of raw native starches. The optimum activity of the enzyme was 30.96 U/ml-min. Partial purification using ammonium sulphate saturation was attained at 50% (NH 4) 2 SO 4. The enzyme was stable over a wide range of pH (4-8) and temperature (30 o C-60 o C). Other optimum values determined were; Ca 2+ concentration-5 mM, starch (substrate) concentration-3%, enzyme-substrate reaction time-6 min and enzyme dosage-4 mg total protein / 3% starch solution. The enzyme was able to hydrolyse the raw starchy substrates studied, producing glucose concentrations of 31.90 mg/ml, 24.78 mg/ml, 19.31 mg/ml and 8.85 mg/ml from maize, sweet potato, yam, and cassava respectively. The optimal substrate concentration of these substrates investigated also showed that different starchy substrates behaved differently towards hydrolysis by amylase. The study has shown the possible production of a local enzyme that was capable of hydrolyzing raw native starches with good activity. This result indicates the possibility of less dependence on imported enzymes.