Detection of tetracyclines with luminescent bacterial strains

The performance of two bioluminescent Escherichia coli K-12 strains for the specific detection of the tetracycline family of antimicrobial agents was compared, and the analytical applicability of one of the strains was prelim inarily evaluated. One sensor plasmid contained the bacterial luciferase op eron of Photorhabdus luminescens under the control of the tetracycline-resp onsive element from transposon Tn10 (15). An analogous plasmid construction with firefly (Photinus pyralis) luciferase reporter gene was constructed, and these two divergent tetracycline-inducible light-emitting systems were compared for their suitability for the qualitative detection of tetracyclin es. Both sensor strains behaved in a similar manner kinetically, and the mo st sensitive tetracycline response for both sensor strains was achieved in 90-120 min by performing the assay at 37 degreesC. The sensor strain contai ning the bacterial luciferase operon responded slightly more sensitively to different tetracyclines than the strain containing firefly luciferase gene . The sensor bacteria retained their inducibility in lyophilization, and fr eeze-dried cells detected tetracyclines as sensitively as freshly cultivate d sensor cells. The preliminary results from the analysis of tetracycline-s piked pork serum samples indicated that these sensor bacteria could be used to screen veterinary samples for tetracycline residues in real-time. Copyr ight (C) 2000 John Wiley & Sons, Ltd.