EXPERIMENTAL ANALYSIS AND SIMULATION OF BACTERIA CHEMOTACTIC BEHAVIOR IN RESPONSE TO ANTIBACTERIALS

Abstract

Bacteria plays an important role in a great number of biological reactions in living species, such as food digestion [1] or in natural environments, such as lakes and soil [2]. As bacteria’s natural predators, bacteriophages target bacterial cells with high specificity. Co-discovered by Frederick Twort (1915) and Felix d'Hérelle (1917), bacteriophages (or for short “phage”) were used as the sole antimicrobial for treatment of infectious disease, before they were overshadowed by antibiotics in 1940 [3]. However, the rising concern over antibiotic resistance in the past decade resulted in a renewed interest towards phage antimicrobials [4]. In this study I designed microfluidic devices for studying bacteria interaction with antibiotics and viruses. Motile bacteria cells can move toward chemo-attractant or away from chemo-repellents. Hence, I quantified bacteria response to these 2 stressors in term of total displacement of cells. In addition to the experimental results, I calculated bacteria displacement for control experiment and 2 stressors by simulation of bacteria chemotaxis. Comparing the simulation and experimental results in the experiments, I identified bacteria chemotactic sensitivity, X0, that relates chemical gradient concentration to chemotactic velocity. For future direction of this study, we suggest designing and develop a microfluidic device able to separate bacteria by exerting different drag forces to different cells. Discrepancy in the chemotactic properties of a single bacterium, such as resistance of the cell to a specific antibacterial, results in different chemotactic velocity of the cell. This distinct cell will move in a different chemotactic velocity compared to the rest of the homogenous population and hence will be exerted to a different drag force. With a proper design, different drag forces can direct cells to different chambers and hence separate cells with respect to their chemotactic response. Such a device can be used for detection of resistant bacteria to a specific antibacterial.