Distribution and biosynthesis requirements for L-Asparaginase activities in bacteria and yeasts

ABSTRACT

Screening of 40 bacterial cultures, belonging to 16 genera and 24 yeasts, belonging to 10 genera, for levels of L-asparaginase activities was carried using a simple medium with L-asparagine asthe major carbon and nitrogen source. Among bacteria highestenzyme levels were noted for certain cultures of Erwinia, Arthrobacter and Serratia; whereas some species of Rlhodotorula, Debaryomyces and Schwanniomyces yielded the highest L-asparaginase activities among the yeast cultures tested. The use of cells stored frozen for a few days was necessary to obtain reliable information about the enzyme levels in the surveyed cultures. Physiological studies on selected cultures have revealed that the enzyme is inducible with L-asparagine and some structurally-related metabolites in Rhodvmruia rubra and Aerobacter aerogenes, whereas in several other cultures the enzyme is formed constitutively. Ammonium ion was a potent supressor of enzyme biosynthesis. Highest enzym levels were detected in cultures during the exponential and at the beginning of the stationary phases of growth whereas a wide variation in the enzyme stability was noted in different cultures upon extended incubation