Research

The Ford group studies chemotaxis and its applications to environmental and medical systems.

Research Areas

  • The Role of Chemotaxis in Marine Microorganism Transport Toward Hydrocarbon Component in An Oil Spill


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    Chemotactic bacteria have the ability to sense the hydrocarbon pollutant gradient, swim toward it and further degrade hydrocarbons. This process can increase the mass transfer of chemotactic bacteria to the hydrocarbon pollutants and can increase biodegradation. The objective of this research is to quantify bacteria motility and chemotactic parameters in order to understand what extent does chemotaxis contribute to increasing the transport process of hydrocarbon-degrading marine bacteria to oil droplets. This proposed work is important to understand the extent to which bacterial chemotactic processes contribute to marine bacteria migration to hydrocarbons. It will also provide information on bacteria migration in complex contaminated marine environment.

  • Bacterial chemotaxis toward discrete hydrocarbon sources


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    Chemotactic bacteria can migrate preferentially to attractants like hydrocarbons, and potentially increase the efficiency of bioremediation in contaminated area. This study aims at multiple length and time scales to investigate the conditions where chemotaxis will overcome the mass transfer limitation in the biodegradation reaction. Numerical simulation was utilized to visualize bacterial distributions inside a sand column packed with discrete hydrocarbon sources. Two microfluidic devices were designed and fabricated to directly observe bacterial behaviors near 1) oil droplets trapped in a heterogenous media and 2) an oil-water interface, respectively. We hypothesize a dimensional scaling method to relate the observations in different length and time scales. This method can help evaluate the importance of chemotaxis for in situ treatment.

  • Nanocarrier delivery of cell signaling agents for biofilm control


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    Bacterial biofilms at fluid interfaces are harmful to human health, agriculture, and oil recovery. Bacteria in biofilms have up to 1000x increased antibiotic resistance, and there is a demand for alternative treatments. Non-lethal cell signaling agents that interfere with critical bacteria transport and cell-cell communication biofilm processes have potential to meet these criteria. In collaboration with the Prud’homme lab at Princeton University, the cell signaling agents are loaded into polymeric nanocarriers for localized delivery at air-water and oil-water interfaces. Two classes of signaling agents are proposed: (1) a novel chemorepellent treatment that will interfere with bacteria transport to the interface, and (2) a fatty-acid signaling molecule that inhibits and disperses biofilm growth. The research objective is to characterize the time and length scales of bacteria transport and biofilm growth at the fluid interface. This will provide baseline design criteria for nanocarriers that competitively adsorb to the interface and release signaling agents to achieve reduced biofilm formation. The dynamics of biofilm formation and NC delivery are investigated with confocal microscopy, where biofilms are grown at planar air-water and oil-water interfaces in a microtiter plate.

  • Sonification of Bacterial Chemotaxis and Motility Patterns


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    Most scientific data is represented visually. However, our ears are powerful tools as well, able to interpret differences in pitch, amplitude, and timbre of sounds. The goal of sonification si to take data that is traditionally represented visually and present it in the form of sound, and see if it can be interpreted in the same way. We want to apply the concept of sonification to bacterial motility through the use of Fast Fourier Transforms on images and videos of bacteria swimming, turning them into audible melodies. Our goal is to be able to distinguish events and behaviors such as chemotaxis that are not visible to the eye by converting the data into sound. We have already found pronounced melodic differences between chemotaxizing and non-chemotaxizing bacteria as well as between strains of different motilities. My current research involves understanding what features of our data are being captured in our sonification as well as perfecting it as an analytical tool.

  • E. coli chemotaxis toward pH gradient in a hydrogel


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    Pathogenic Escherichia coli (E. coli) strains that invade the human body, usually through the consumption of contaminated foods, can have several detrimental effects on the host, but treatment of E. coli that have trespassed into the gastrointestinal microbiome is heavily under­investigated, even though it is the second most common cause of death in children in low income countries. The behavior of common E. coli strains in the colonization of protected surfaces, such as the mucosal layer that surrounds internal organs, has been found to support chemotaxis. However, such models do not fully reflect an in vivo environment, since the flora of the intestine is exposed to several other factors that could impact the motility of E. coli. It is observed that during stomach infections, acidity of the mucus in the stomach decreases, thereby impacting the pH gradient (which acts as a repellent for bacterial migration). It is therefore desired to evaluate the chemotactic behavior of E. coli in the presence of a pH gradient as it distributes in a hydrogel.

  • Soil percolation thresholds for chemotactic bacteria to migrate via water-filled pathways toward root nodules for nitrogen-fixation in leguminous plants


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    Next to water, nitrogen is one of the most essential nutrients for plant growth. In commercial agriculture this is accounted for by supplying mass amounts of nitrogen based fertilizer to crops; a practice well known to cause major environmental collateral damage such as toxic algae blooms and soil nutrient depletion. Plants naturally gain access to ammonia, the form of nitrogen needed for growth, via a symbiotic relationship with soil bacteria that locally fixes atmospheric nitrogen in a nodule. In this study, the ability of Bradyrhizobia Japonicum to chemotactically move to the roots of these plants is studied. Because bacteria move via water filled pores, saturation levels and pore size in soil greatly affect the number of available pathways that grant access to plants. By varying the matric potential of the soil, it we will quantify the saturation level of varying soil makeups that is required for nodulation.