(4am) Extending a Microfluidic Platform to Elucidate Bacterial Communication in Humans Its Impact on Disease

Research Interests include adapting a microfluidic platform to understand mechanisms that lead to diseases in the host. As a PI, I will first design and develop screens that identify gene determinants for disease. I will also develop model systems that simulate natural environments to culture and conduct competition experiments. I will also develop a microfluidic pipeline for investigating the effects that individual hosts have on mechanisms for disease.

Bacteria are ten times more abundant than host cells in the human body and their interactions between each other and the host cells are often complex, leading to life-threatening infections that cause diseases. For instance, Streptococcus pneumoniae (Spn), a major human pathogen that causes over a million annual deaths in young children and the elderly, worldwide, also colonizes the human nasopharynx of many humans without causing any symptoms in its commensal form. In addition, the displacement of vaginal lactobacilli by strict anaerobic bacteria in the vagina is characteristic of bacterial vaginosis (BV), the leading cause of healthcare visits for women of reproductive age. Many questions remain about how bacteria switch from being a commensal to a pathogenic strain. To answer these questions, I adapted a microfluidic platform that enables high-parallel cultivation of bacteria in order to dissect and characterize microbial interactions in droplets using a water-in-oil emulsion that creates thousands of monodisperse mini-bioreactors.

During my dissertation, my goal was to develop a proof of concept to demonstrate microdroplets as an effective tool for co-culturing and recapitulating negative interactions between vaginal bacteria. My results recapitulated the killing effect of a health-promoting vaginal bacterium, against two vaginal putative pathogens, both in individual and pooled droplets. This project was the first to demonstrate co-cultivation and interactions of vaginal bacteria in droplets, used pneumatic sorting to isolate individual droplets to count cells, and presented a new technique that used less chemical reagent, lower costs, and high-parallel experiments to study microbial interactions in the vagina. The goal of my second project determined the effect of limited iron availability on growth of Lactobacillus crispatus and L. iners. I found that limited iron decreases growth of L. iners, but has no effect on growth of L. crispatus. These findings raise questions as to the mechanisms for iron sequestration for L. iners and L. crispatus, how they survive during menses when iron becomes available, and the influence of iron uptake on population dynamics. I also developed a method to pool vaginal fluid based on similar vaginal microflora and I discovered that L. iners grew in L. crispatus-dominated vaginal fluid. My work developed a novel method for culturing a hard to grow bacterium, ex vivo using sterile-filtered human vaginal fluid, and developed a model system simulating the human vagina, which has further implications for studying microbial interaction ex vivo.

The goal of my postdoc is to investigate which molecules and pathways coordinate processes in Spn that influence disease. I will first demonstrate cell-cell communication between peptides and a Spn strain using a fluorescent reporter that is induced by exogenous peptides. Real-time detection of induction will enable high-throughput screens to enrich for strains and/or peptides from several reported gene networks. I am also working with two Master’s students to build a fluorescent droplet sorter to enrich for species that are peptide-induced, and to select for peptide inhibitors that can mitigate virulence factors in Spn, respectively. This work has further implications for developing and screening for a new class of antimicrobial peptides.

My teaching interests include all of the core classes in chemical engineering. I am also interested in designing and teaching the course, biomedical applications for microfluidics.