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Abstract
A survey of ten isolated fungal strains was carried out for the production of fungal xylanases. Aspergillus flavus isolate NERMEEN12 was the strain with the highest xylanase activity. Xylanase enzyme was produced by aspergillus flavus isolate utilizing different agricultural wastes rice straw, corn cobs, wheat bran, wheat straw and saw dust by solid state and submerged fermentation techniques. The highest xylanase production was obtained by solid state fermentation in the following order corn cobs >rice straw >wheat straw >wheat bran> saw dust. Enhancement of xylanase production was achieved by two statistically-based experimental designs to optimize the fermentation medium. The plackett-burman multifactorial design was first employed to investigate the effect of 19 factors on xylanase production. The most significant factors found to be, CaCl2.2H2O, CuSO4, CMC and NaCl. Further optimization was done using taguchi L9 (3^4) orthogonal array design, by which the effect of four factors in three levels, could be tested. The taguchi design showed that the maximum yield of xylanase was produced when CaCl2.2H2O, CuSO4, CMC and NaCl were present in the fermentation medium in concentrations (g/l): 1, 0.2, 10 and 10 respectively. Under optimal conditions enzyme production was increased by 2.4-fold compared to the non optimized medium