THE EFFECT OF R-PLASMID ON L-ASPARAGINASE ACTIVITY OF ESCHERICHIA COLI / 微生物学通报

ABSTRACT

L-asparaginase activity produced by six E. coli J53 strains containing different plasmids and plasmid free E. coli J53 strain was compared. The enzyme activity of the plasmid- bearing strains was about 2—4 times lower than that of the plasmid free ones. Curing the R plasmids from E. coli J53, the activity of L-asparaginase increased and was close to that of the plasmid free strain. It is proved that the remarkable inhibition of L-asparaginase activity results from the presence of the plasmid in E. coli.