Escherichia coli (E. coli) has been used as a biosensor for detection of a wide range of analytes such as TNT, insecticides or lead. Glyphosate is a widely-used herbicide in US agriculture that can pose harms to marine life, mammals and endangered species. Due to the structural similarities between glycine, an amino acid that has known metabolic processes in E. coli, and glyphosate, it was hypothesized that a promoter in the E. coli transcriptome that would respond to glyphosate. The Weizmann K12 MG1655 promoter library is used in this study in order to isolate promoters that are sensitive to glyphosate. The proposed methods utilize fluorescent-activated cell sorting (FACS) and next generation sequencing (NGS) as a high-throughput screening process through the entire library of 1900 promoters. The primary goal is to isolate promoters sensitive to the analyte with a further goal of putting together a biosensor in E. coli that can be used to detect glyphosate that would drive down cost and labor compared to other detection methods like gas chromatography or high performance liquid chromatography. An inhibitory study was performed using the plate reader to determine the inhibitory concentration (IC50) of glyphosate for E. coli, which was found to be 62.36 ppm. The results from FACS indicated a possibility that a more refine sorting procedure was required to fully isolate sensitive promoters. Future works include a phenotypic study on isolated promoters to confirm the sensitivity of these promoters towards the analyte and the construction of an E. coli-based bacterial sensor that can detect glyphosate in water sources.
Author(s): Huy Bui, Biochemistry Major
Advisor(s): Kevin Yehl, Department of Chemistry and Biochemistry
Kevin Morrison, Department of Chemistry and Biochemistry
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