BRIGE awards maintain global competitiveness by increasing the diversity of ENG researchers, who are initiating research programs early in their careers. BRIGE awards further the broaden participation of engineering researchers by increasing the number of engineering graduates, by improving the representation of women and minorities in engineering, and by understanding how to improve recruitment and retention of engineering students.
Initial attachment of pathogenic bacteria to a surface is considered a key preliminary step in biofilm formation and subsequent infections. For many years, research to understand the attachment mechanisms focused on macroscale exploration of the effect of factors such as roughness and motility on the attachment. While such macroscale investigations can be very interesting, molecular-scale studies of bacterial interactions with surfaces can detail the molecular mechanisms of attachment. Despite the importance of such molecular-scale measurements, a clear relationship between the molecular properties of bacterial surface biopolymers and the adhesion of pathogenic microbes to surfaces does not exist. Motivated by the lack of such studies, this research aims to provide a preliminary understanding of the molecular effects of bacterial surface biopolymers on the initial attachment of Listeria monocytogenes to a model surface. The central hypothesis of this application is that surface biopolymers of L. monocytogenes are essential molecular components that strongly affect the bacterial surface charge, wettability, and elasticity and thus initial attachment of this microbe to surfaces. The PI will research the molecular effects of the surface biopolymers of L. monocytogenes on their initial attachment to surfaces using atomic force microscopy (AFM). AFM is unique among adhesion measurement techniques in its ability to quantify the interaction forces between bacteria and surfaces at a molecular level in liquid media that mimics that in which interactions occur. The results of this application will be instrumental to researchers designing new effective preventive and treatment strategies to bacterial infections.
The PI will intertwine the research with educational activities integrating mathematics and bioengineering with the training of graduate and undergraduate students from diverse backgrounds. The education plan will: 1) provide mentored teaching and research experiences to a team of students consisting of a graduate student, two upper-level women engineering students, and two freshman disabled undergraduate students; 2) develop a teaching module that can be incorporated into upper-level bioengineering courses to enhance effective student learning of mathematical modeling and curve fitting; and 3) collaborate with an existing NSF GK-12 grant to incorporate hands-on experiments in the mathematics curricula of middle and high school students. The educational activities are geared to enhance the learning and scholarship of the participating students, especially those underrepresented in engineering, and to nurture their self-growth to be more independent and lifelong learners and researchers. The participating students in these educational activities are expected to gain an appreciation for the excitement of scientific research, learn to read and interpret scientific literature, design, perform, and analyze experiments, communicate their findings in both oral and written format, and work well within a team. Finally, the outreach hands-on experiments are expected to strengthen the middle and high school students' performance in mathematics and stimulate their interests in engineering. The results of the research will be disseminated to the scientific community through seminars, technical journal papers, and professional conference presentations and to the general public through news releases.
This BRIGE grant will broaden the participation of and increase opportunities for all engineers including those from groups underrepresented in the engineering disciplines. This BRIGE grant will also encourage the PI to become actively and competitively engaged in research as an independent investigator.
Intellectual Merit. Pathogenicity is the ability of bacteria to cause disease. Contamination of food or other inert surfaces such as implants is considered as a key preliminary step in the ability of the bacteria to cause infections. Controlling bacterial attachment and pathogenicity is thus vital to improving the prosperity of humans. For many years, research designed to understand the mechanisms of how bacteria attach to surfaces was focused on macroscale explorations of the bacterial adhesion phenomenon. For example, investigations of the effect of roughness, nutrient availability or temperature on how bacterial communities survive and attach to surfaces in the environment were performed. While macroscale investigations can be very interesting, fundamental studies of how bacteria interact with surfaces can detail the molecular mechanisms of attachment. Fundamental understanding of bacterial adhesion mechanisms is expected to be instrumental to researchers designing tools to predict, diagnose, control and treat bacterial infections. Our research was focused on investigations of molecular mechanisms of adhesion of pathogenic L. monocytogenes to a model surface of silicon nitride. L. monocytogenes is considered a super bug that contaminates ready-to-eat food products and survive in extreme environmental conditions. Silicon nitride was chosen as our model to mimic soil and glass. Soil and glass are surfaces to which L. monocytogenes attach to frequently in nature. To quantify how L. monocytogenes attach to surfaces, atomic force microscopy (AFM) was used. AFM is unique among adhesion measurement techniques due to its high resolution and its ability to quantify adhesion on a single bacterial cell at a molecular level in liquid environment. Our results indicated that the pathogenicity of bacterial cells is logarithmically correlated with their adhesion abilities. This indicates that the stronger pathogens are better survivors in the environment. The ability of stronger pathogens to adhere better in comparison to less-pathogenic ones was found to be correlated with a higher surface composition of proteins, longer surface macromolecules and more rigid surfaces. Broader Impacts. Improving our understanding of the mechanisms that control bacterial adhesion and virulence is important for improving the health and prosperity of humans and to improving the economy of the US by decreasing the costs associated with treating infections. The research activities proposed were integrated with a continuum of educational activities. I have provided mentored teaching and research experiences to 11 undergraduate students from diverse backgrounds. Among the students mentored, 8 were women, 2 were students with disabilities, 2 were freshmen students and 2 students were science major versus nine engineering majors. In addition, one female and one male graduate students were supported on this grant. The students were trained to use a wide array of equipment including AFM, scanning electron microscopes and tensiometers. Students as well were trained to work well within teams, write technical reports and present their results orally. We have worked as well on many outreach activities. First, we have hosted four high school teachers to work in our lab for six weeks during the summer. All teachers were able to develop hands-on activities that can be used in their classrooms to improve students’ abilities to grasp scientific and mathematical concepts on the interface of science and engineering as well as to stimulate the interests of their students in engineering as a major. High school teachers represented largely schools that are highly populated with Hispanic and Native American students. Second, hands-on modules were developed and integrated in my "Introduction to Cellular Bioengineering" class to improve students’ abilities to apply mathematical models to experimental data. Third, I have presented our research and teaching results to minority Latino students, to freshmen engineering students at WSU by collaborating with an existing NSF grant, to REU students at WSU, to high school students through a program titled "Imagine U at WSU" and to a wide audience of WSU students through a workshop series titled "Inspiring new generation of scientists and engineers". Our research and educational results were published in four peer-reviewed journals and in one conference proceeding, respectively. Our research and educational results were presented in 17 national and local conferences.
