Escherichia coli and Salmonella pullorum Adherence to Spinacia oleracea Leafs
Authors:Breanna Caso, Jessamine Flores, Cody Gonzalez
- Heather Smith, Professor of Life Sciences, Riverside City College
- Sharon Walker, Associate Professor and the John Babbage Chair in Environmental Engineering, University of California, Riverside
Various pathogenic bacteria are able to contaminate leafy green produce, which poses a significant health hazard in agriculture. This study aims to determine the attachment and detachment behavior of Escherichia coli 0157:H7 and Salmonella pullorum on Spinachia oleracea (spinach). Green Fluorescent Protein (GFP) transgenic bacteria were used to examine the mass transfer of bacteria to varied deposition sites. This parallel plate flow system enables the quantification of deposition events under various solution chemistries relevant to agriculture. Characterization of the GFP transgenic bacteria Escherichia coli 0157:H7 g and Salmonella pullorum g were done via electrophoretic mobility and hydrophobicity. Groundwater can be contaminated through the seepage of bacteria into groundwater deposits. This water can then contaminate leafy greens through sprinkler systems and irrigation. The GFP transgenic bacteria will be placed in simulated groundwater and flowed onto the epicuticular wax of the spinach leaf. This is done to measure adherence rates of said bacteria under replicated agricultural conditions. The wax is isolated using liquid nitrogen as well as through a chemical extraction method. The isolated wax is tested using Gas Chromatography (GC) and through a Carbon NMR to determine whether it is composed of the appropriate carbon length chains to prove the isolated wax contains only the epicuticular wax of the spinach. Preliminary results have yielded Salmonella pullorum and Escherichia coli 0157:H7 mutants through electroporation. Further study into this research will provide better techniques for sterilizing and removing bacteria from leafy green produce and will pave the way for safer leafy greens agriculture.