Optimization of L-glutaminase synthesis by Aspergillus oryzae NRRL 32657 in submerged culture

Various fungal strains have been screened for L- glutaminase synthesis. Aspergillus oryzae NRRL 32657 proved to be the highest producer (24.19 U.ml-1) with the largest pink zone diameter (8 mm). Production of L- glutaminase (E.C. 3.5.1.2. L-glutamine amidohydrolase) by A. oryzae in batch submerged system was optimized. Several factors: incubation period, source and concentration of carbon, source and concentration of nitrogen, initial pH level, incubation temperature, amino acids source and concentrations and sodium chloride concentration were tested for their effect on enzyme synthesis. The highest L- glutaminase synthesis (46.53 U. ml-1) was achieved when A. oryzae was allowed to grow aerobically (30ºC for 3 days) in a buffered medium (pH 7.0) containing 2.5% lactose, 2% yeast extract, 0.5% L- glutamine and 0.5% sodium chloride.