Comparison of Two Nitrogen Sources for Aspergillus spp. Phytase Production

Abstract

The study on phytase enzyme production of the three Aspergillus spp. : Aspergillus ficuum NRRL 3135 (AF1), NRRL 320 (AF2) and A. niger (AN) had been conducted. Two nitrogen sources (ammonium and sodium nitrates) were used in the medium and two working incubation temperatures (30 and 37OC) were applied. The aimed of this study was to obtain the low-cost nitrogen source for optimum phytase production. All fungi were incubated in media M0 and M1 for 12 days for enzyme production. Analysis for enzyme activities, protein and sugar content and biomass production were performed at day 2,3,4,6,8,and 12 days of incubation periods. Phytase activity was lower in sodium nitrate medium for all Aspergillus spp than in ammonium nitrate medium (2.39, 1.65, 1.65 vs 4.19, 2.22, 2.22 U/ml for AF1, AF2 and AN respectively) at 30OC of incubation temperature. These enzyme activities were reached for 8 days incubation time. The phytase activities of all Aspergillus spp at 37OC incubation temperature were 2.07, 1.24, 1.36 vs 4.80, 2.04, 2.34 U/ml for sodium nitrate vs ammonium nitrate medium and reached at 4 days incubation period for both A. ficuum and 3 days incubation period for A. niger in the M0 medium. It was clearly shown that incubation temperature at 37OC shortened the fermentation period to reach optimal enzyme activity and ammonium nitrate produced higher enzyme activity when compared with sodium nitrate medium.