A new rapid and sensitive bioluminescence assay for antibiotics that inhibit protein synthesis

A new sensitive, rapid and simple bioluminescence assay for antibiotics inhibiting protein synthesis is described. In this assay the ability of the tested antibiotic to inhibit the de novo synthesis of the enzymes participating in the bacterial luminescence system is determined by means of a dark variant of a luminous bacterium that undergoes prompt induction of the luminescence system with certain DNA-intercalating agents. Upon induction, the in vivo luminescence of the dark variant is increased more than 50-fold within 30 min. Antibiotics that block the de novo synthesis of protein limit the development of luminescence at a level that was found to be a function of the antibiotic concentration. The minimum detectable concentration of antibiotics in the bioluminescence test, after 45-60 min of incubation, was 0.1 microgram/ml for streptomycin, gentamicin, kanamycin, lincomycin and chloramphenicol and 0.3 microgram/ml for neomycin, clindamycin and spectinomycin. The new bioluminescence test has been used to assay these antibiotics in serum.