Formation and properties of L-Glutaminase and L-Asparaginase activities in pichia polymorpha

ABSTRACT

An ascogenous yeast with high potentialities for L-glutaminase and L-asparaginase formation was isolated from Egyptian soils by the application of the method of enrichment culture. The organism, identified as pichia polymorpha, was obtained through the enrichment of the soil samples with a simple medium containing 0.5% L-glutamine as a major carbon and nitrogen source at low pH values. - The amidase activities were produced constitutively on a variety of media irrespective to the presence of their substrates in the growth medium. The assays of enzyme activity have revealed that optimum pH values for L-glutamine and L-asparagine hydrolysis are 6 and 6.7 respectively. The L-asparaginase activity of the cells were heat-stable at least up to 10 min at 600. The enzyme exhibited apparent km of 1.37 x 10[-2] M and 1.95 x 10[-2] M for L-asparagine and L-glutamine respectively. No metal requirements were detected for the amidase activities of the organism under study