Utilization of Agro-Industrial Waste Residues for the Production of Amylase from Aspergillus oryzae IIB-6

Abstract

Aims: The aim of this study was to evaluate different solid substrates and moistening agents for the production of an extracellular 1, 4-α-D-glucan glucohydrolase from a newly isolated Aspergillus oryzae IIB-6 by solid state fermentation and optimization of culture conditions for the maximal production of enzyme. Study Design: Six different agro-industrial waste residues (rice straw, rice bran, corn flakes, wheat bran, wheat flakes, and grinded wheat kernel) were procured from the local market. These substrates (10 g) were moistened (1:1) with different moistening agents (distilled water, tap water, mineral salts solution (FeSO4.7H2O 0.02, MgSO4.7H2O 1.0, (NH4)2SO4 4.0, KH2PO4 0.6, K2HPO4 1.4 mg/gds at ph 5), 0.1 N HCl, sodium acetate buffer (pH 5.5), sodium phosphate buffer pH 7.5) and screened for the production of 1,4-α-D-glucan glucohydrolase for 96 hours in static cultures. The substrate and moistening agent that gave maximum enzyme production were selected and their fermentation conditions were further optimized. Place and Duration of Study: Institute of Industrial Biotechnology (IIB), GC University Lahore, Kachery Road Lahore, Pakistan, between February 2011 and March 2012. Methodology: The levels of selected solid substrate, moistening agent and fermentation conditions such as pH, temperature, time of incubation, inoculum size etc. were optimized by one variable at a  time method.  Results: Wheat bran at the level of 5 g and mineral salts solution containing FeSO4.7H2O 0.016, MgSO4.7H2O 0.8, (NH4)2SO4 3.5, KH2PO4 0.48, K2HPO4 1.12 mg/gds gave relatively best enzyme production. The maximum enzyme activity 7800 U/gds (407 Umg-1 protein) were achieved when wheat bran with 80% moisture content was incubated at 30°C, pH 5, after inoculating with 10% spore suspension (1.2×106 CFU/gds) for 72 h. Conclusion: Aspergillus oryzae IIB-6 was a good producer of 1,4-α-D-glucan glucohydrolase in wheat bran medium containing mineral salts as an additional trace elements so that it can be used for biotechnological purposes.