Upgrading of naringinase production by gamma irradiated Aspergillus niger uilizing agro-industrial processing wastes

Naringinase-producing microorganisms were isolated locally from some citrus fruits and soil using a culture enrichment technique, and they were tested for their enzyme producing ability in shake flask cultures. Among the tested microorganisms, aspergillus niger-AH3 proved to be the most potent active isolate which gave 92.1 UMl-1 of naringinase activity in fermentation medium. Optimization effects of various fermentation medium constituents of agro-industrial processing wastes as substrates for naringinase production were studied. Of substrates used, corn steep liquor, soya bean meal, jojoba seed meal and bitter orange seed powder were the best for naringinase production .Maximum enzyme titer (145.5 Uml-1) was obtained in the optimized fermentation medium supplemented with 0.5% CaCo3 after 120 h of incubation. The highly potent ten enhanced isolates which were selected after treatment with gamma irradiation, had significantly elevated titers of naringinase activity compared with the parental wild strain A. niger-AH3. Enhanced isolate A. niger-AH3. γ20 derived from 2.0 kGy treated groups is exhibiting the highest enzyme activity 1.5 folds higher than parental strain. This suggests that a process for efficient utilization of the agro-industrial processing wastes in economical production of naringinase in large quantities which would be suitable for debittering process in the citrus fruit juice industry