Screening for type II L-Asparaginases: Lessons from the genus halomonas

Among the two types of bacterial l-asparaginases,only type ii enzymes have been used in the treatment of acute lymphoblastic leukemia owing to their higher affinity for l-asparagine. however,current screening media used for the isolation of l-asparaginase-producing microorganisms do not discriminate between the two types of l-asparaginase. during an optimization study conducted to increase l-asparaginase production by environmental halomonas isolates,it was noticed that the pattern of l-asparaginase production in response to variations in glucose concentration varied between different isolates suggesting that they differ in their ability to produce type ii l-asparaginases,an observation that was confirmed by further experiments. bioinformatics analysis of available halomonas whole genome sequences revealed that indeed some species of this genus possess both l-asparaginase types while others possess only type i enzymes. by comparing the growth pattern of these isolates on different media,we propose that by omitting glucose,reducing the concentration of l-asparagine and providing an alternative nitrogen source in l-asparaginase screening media it may be possible to differentiate between type i and type ii activities. © 2017 by school of pharmacy shaheed beheshti university of medical sciences and health services.