Objective: Photocatalytic materials such as titanium dioxide (TiO2) have been widely studied for their applications as auto cleaning agent, deodorant, antibacterial, and for purification of water and air. There are several reports on the bactericidal effect of a TiO2 photocatalyst, however, in our knowledge, this work is the first report on the effect of the TiO2 based films on bacterial activity of a luminescent bacterial biosensor. Materials and Methods: The luminescent strain Escherichia coli SM10 S1 was constructed by insertional mutagenesis using mini Tn-5 luxAB transposon harboring in plasmid pUT. Light output intensity and chromosomal stability of luxAB genes were evaluated much suitable to be used as a microbial biosensor. E.coli cell suspension was pipetted onto TiO2-coated glass with different calcinations temperatures (400˚C, 405˚C, 500˚C, 550˚C) and placed under a UV illumination chamber at define time exposure. After illumination, the bacterial cells were removed and their luminescent activity was measured by luminometer. Results: The evidences showed that after 1h exposure of different TiO2-coated glass slides to UV irradiation, luminescence light out put of E.coli SM10 S1 were higher in glass without TiO2. Among TiO2-coated glass slides, those with calcinations temperature of 405˚C and 500˚C did have more inhibition effect than two others. However when UV exposure time decreased to 20 min all type of TiO2-coated glass slides had inhibition effect on the rate of luminescent light out put. Conclusion: In this study, we assessed the photocatalytic inactivation with TiO2 thin film against luminescent activity of genetically engineered bacterium E. coli SM10 S1 and found that different calcinations time can effect variously on activity of above bacterium.

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