OXIDATIVE STRESS DETECTION WITH ESCHERICHIA-COLI HARBORING A KATG'--LUX FUSION

A plasmid containing a transcriptional fusion of the Escherichia coli katG promoter to a truncated Vibrio fischeri lux operon (luxCDABE) was constructed, An E, coli strain bearing this plasmid (strain DPD2511) exhibited low basal levels of luminescence, which increased up to 1,00 0-fold in the presence of hydrogen peroxide, organic peroxides, redox- cycling agents (methyl viologen and menadione), a hydrogen peroxide pr oducing enzyme system (xanthine and xanthine oxidase), and cigarette s moke, An oxyR deletion abolished hydrogen peroxide-dependent induction , confirming that oxyR controlled katG'::Lux luminescence, Light emiss ion was also induced by ethanol by an unexplained mechanism, A marked synergistic response was observed when cells were exposed to both etha nol and hydrogen peroxide; the level of luminescence measured in the p resence of both inducers was much higher than the sum of the level of luminescence observed with ethanol and the level of luminescence obser ved with hydrogen peroxide, It is suggested that this construction or similar constructions may be used as a tool for assaying oxidant and a ntioxidant properties of chemicals, as a biosensor for environmental m onitoring, and as a tool for studying cellular responses to oxidative hazards.