Stress response in E. coli exposed to different pharmaceuticals

The hazardous effect of four widely consumed pharmaceuticals (caffeine, ibuprofen, aspirin and tetracycline) has been studied. Escherichia coli has been used as a comparison organism for the four stress responsive genes, grpE, recA, katG and fabA, which are useful biomarkers of the protein damage, DNA damage, oxidative damage and membrane damage caused by these pharmaceuticals, respectively. The growth rate has been found to depend upon the time of exposure and the concentration of pharmaceuticals. The expression levels of these four genes, quantified by semi-quantitative reverse transcription-PCR, show different responsive patterns when the E. coli cultures were under stressful conditions caused by exposure to these four pharmaceuticals in different concentrations. The stress responsive gene grpE is more sensitive to aspirin and tetracycline, recA is responsive to caffeine and aspirin, katG is responsive to ibuprofen only whereas fabA is responsive to tetracycline only. The extent of stress responsive effect caused by these pharmaceuticals has been analyzed and most responsive genes have been identified for each pharmaceutical.