غربالگري سويه هاي باكتري اشرشياكلي جهت توليد آنزيم آسپاراژيناز II

Screening of Esherichia coli strains for asparaginase II production

L-asparaginase II from Echerchia coli has been supplied and employed in the acute leukemia. In this investigation, the various strains of E. coli including LAB, K12, DH5a and TOPTEN were tested for ansB gene by PCR reaction. The strains with ansB gene were cultured and as the absorbance at 600 nm reached to 1, the expression was induced by anaerobic induction. After induction, cells were harvested and the supernatant and periplasmic content of cells were tested for asparaginase activity. Asparaginase activity was measured by determining the rate of amonia formation. Screening of E. coli strains by PCR reaction revealed the ansB gene in LAB, K12 and DH5a strains of E. coli. Neither periplasmic nor supernatant of these strains had asparaginase activity aerobically. The amonia formation in all strains was almost the same anaerobically and about 0.01 iimol (3.6 unit/ml). The maximum enzyme production was at induction duration of 1 hour in E. coli LAB and DH5a, and 40 minutes in E. coli K12. The enzyme production decreased 3 hours after anaerobic induction (2-2.5unit/ml).