OPTIMIZATION OF FERMENTATION MEDIUM FOR α-AMYLASE PRODUCTION BY FREE AND IMMOBILIZED Aspergillus niger ON PALM TREE FIBERS

El-Shimi, Nagwa M.; Bazaraa, W. A.; Abou Al-Alla, Reda M.

doi:10.21608/jacb.2007.201362

OPTIMIZATION OF FERMENTATION MEDIUM FOR α-AMYLASE PRODUCTION BY FREE AND IMMOBILIZED Aspergillus niger ON PALM TREE FIBERS

Document Type : Original Article

Authors

Food Science and Technology Dept. Fac. Agric. Cairo Univ. Giza, Egypt.

10.21608/jacb.2007.201362

Abstract

Various strains of Aspergillus niger were screened for α- amylase synthesis. Strain 3 proved to be the highest producer (1.82 U. ml^-1). Production of α- amylase by Aspergillus niger 3 in batch shaking system was optimized. The highest α- amylase production (5.63 U. ml^-1) at 30 ºC was achieved when Aspergillus niger 3 was allowed to grow aerobically in a buffered medium (pH 7.0) containing 2 % dextrin and 1.6 % tryptone. The enzyme was found to be highly inducible by dextrin, while the presence of glucose or fructose repressed its synthesis. Palm tree fiber (PTF) was evaluated for the first time as a novel fungal cells supporting material. Conidiospores were firmly attached onto the rough surfaces of the PTF as proved by SEM photomicrographs. The immobilized preparations were used in batch system for α- amylase production with maximum sp. activity of 0.49 U. ml^-1.mg^-1. Such sp. activity was improved to 0.8 U. ml^-1.mg^-1 by modifying fermentation broth to contain 0.5 % dextrin and 2.4 % tryptone.