L-asparaginase is a hydrolyticenzyme that primarily catalyzes the conversion of L-asparagine to L-aspartic and Ammonia which has received considerable attention as an anti-acute lymphoblastic leukemia agent in white biotechnology. Normal cells can synthesize L-asparagine with the help of asparagine synthetase, whereas certain sensitive malignant cells cannot synthesize it by themselves and require an external source of L-asparagine for growth. As a result, the enzyme activity can inhibit the growth of tumor cells by consuming the L-asparagine during clinical application.

The Microorganisms bank of the Iranian Biological Resource Center contains a collection of fungal strains that have been isolated throughout the years of research from different parts of the country. In this research, these novel type strains were evaluated for their ability to produce the L-asparaginase enzyme. The efficiency of three different dye indicators including phenol red, bromothymol blue and cresol red were evaluated. Production mode was also evaluated by the agar well diffusion method. A comparative study was carried out to evaluate L-asparaginase production in submerged conditions by an enzymatic assay using Nessler's reagent. Optimization of the enzyme production by the selected superior strain was also performed.

Five type strains showed positive L-asparaginase activity in preliminary screening. Phenol red and bromothymol blue showed a better differentiable zone of hydrolysis and consistent results. L-asparaginase production by Fereydounia khargensis IBRC-M 30116T which showed the highest zone of color change, was then optimized. The optimum enzymeactivity of 61.3 U. mL-1 was obtained with 9% inoculum, at a temperature of 30 °C and at the presence ofammonium chloride as nitrogen source and with glycerol as the carbon sources. The study revealed that, apart from bacteria, yeast could be considered as a novel and appropriatesources for the production of the high yield of L-asparaginase. Theresults of this study were published in theIranian Journal of Science and Technology Transactions A: Science.