The effect of chloramphenicol on the induction of cyanase In Escherichia cott

Abstract

The early stages of cyanase induction were studied. It was found that 30 s elapsed at 37 °C and 60 s elapsed at 22 °C before cyanase-forming capacity of Escherichia coli could be demonstrated. This period was termed inducer-dependent stage (i.d.s.). An additional period of 120 s at 22 °C was needed for demonstration of enzyme synthesis. This period was termed inducer-independent stage (i.i.s.). It was found that in contrast to β-galactosidase, the i.d.s. as well as the i.i.s. were inhibited by chloramphenicol. Pulse-labelling experiments showed an increase in m-RNA obtained from induced bacteria in the presence of chloramphenicol compared with noninduced bacteria treated with chloramphenicol, indicating that chloramphenicol does not interfere with transcription. However, the m-RNA formed in the presence of chloramphenicol did not participate in translation upon removal of the antibiotic. This evidence, in addition to the time course of the inhibition, suggests that the inhibition of induction is caused by chloramphenicol preventing the attachment of the ribosomes to cyanase-specific m-RNA.