Antibiotics are widely produced for the health of humans, livestock and crops. Excess amounts of antibiotics have been released into the environment, resulting in not only extinction of local microbiota, but also the emergence of antibiotic resistance which may cause antibiotic treatment failure in return. When antibiotics are delivered to soil, environmental stress gradients are created, which potentially serve as the key factor driving soil microbes to adapt and evolve. It is difficult, however, for batch culture experiments - the most common method used in most prior studies, to maintain concentration gradients. To address this challenge of studying the interaction between soil microbes and antibiotics, we employ microfluidics in our experiments to mimic settings that contain steep gradients in environmental stresses. Microfluidics enable microorganisms to explore different concentrations of antibiotics, thus allowing them to develop in ecological niches that best fit their physiology. We compare the different behaviors of motile and non-motile Escherichia coli in microfluidics to assess how motility affects the chemotaxis of E. coli with the help of cell fluorescence and time-lapse images. Experimental results reveal that motile cells can better utilize available nutrients in an environment of high antibiotic concentration. Image analysis shows the landscape distribution of microbial culture growth within the microfluidics, and computational models are employed to fit the data. Ongoing genomic analyses will be used to track and analyze mutations in response to each level of antibiotic concentration.

Role of motility in Escherichia coli response to antibiotic gradients in microfluidics

255th National Meeting (2018)

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