Changes in Tolerance of Amphenicol and Tetracylcine Antibiotics with Stress-Responsive Transcription Factor Overexpression in E. coli

Antibiotic resistance has become a global issue due to antibiotic over prescription, indiscriminate use in livestock consumed by humans, and natural evolution of various bacterial species. Bacteria use many mechanisms to evade antibiotic action; one well-studied mechanism is the growth of biofilm, a sedentary state of bacteria surrounded by a hydrated and protective extracellular matrix. We are interested in how the overexpression of specific stress-responsive signaling pathways influence how Escherichia coli tolerate different classes of antibiotics and if the combination of pathway activation and antibiotic treatment changes biofilm formation and composition. We are studying the overexpression of the transcription factors rpoF and rpoH.154N in E. coli in combination with chloramphenicol, florfenicol, and tetracycline. We are measuring the growth of the bacteria using UV-visible spectroscopy to record the minimum inhibitory concentration (MIC) and measuring biofilm growth using a crystal violet assay. Preliminary results show that the overexpression of either rpoH.154N or rpoF enhances the MIC for chloramphenicol above 4.4 µg/mL, the commonly reported MIC for E. coli. Our next steps include narrowing down the MIC for these antibiotics under differing experimental conditions and collecting biofilm growth data.