Community-derived zinc metal regulation from monolayer to biofilm.

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Project Summary and Abstract In humans, the gut is home to the most extensive set of diverse bacteria actively working together to break down nutrients for consumption, defend against pathogens, and train the immune system, as well as actively communicating with the host cells to optimize their survival. The gut microbiome formed shortly after birth changes over time in response to the diet and overall health of the host. When a pathogen invades the gut and adversely affects the host’s health, it is treated with antibiotics. However, the treatment has the side effect of indiscriminately altering the gut microbiome, leaving the host even more vulnerable to a future infection. Communities of bacterial cells maintain a state of homeostasis by actively communicating with each other and the host. This signaling system has the potential to serve as an innovative approach to treat virulent pathogens by recruiting the microbiome’s own defense system. However, it is unclear what metabolites serve as a signaling molecule to coordinate behavior. Transition metals play significant roles as micronutrients necessary to carry out complex chemical reactions required to sustain life. Consequently, their concentrations inside the cells are tightly regulated. This study focuses on zinc metal homeostasis due to its vital role in catalytic, structural, and regulatory functions in Escherichia coli, a model Gram-negative bacterium and a common bacterium in the environment, foods, and intestines. The overall objective of the proposed work is to determine whether zinc can act as a chemical cue to coordinate behavior in a community of cells in the context of metal homeostasis. My central hypothesis is that zinc acting as a signaling molecule can influence the cell’s neighborhood gene expression state to account for a changing environment in which the micronutrient is in low supply, excess, or used as a form of attack by a pathogen or the immune system. The hypothesis will be tested using combined approaches of microfluidics devices, chemical/genetic manipulations, optogenetics, single-molecule spectroscopy, and bulk biophysical/biomolecular/cellular assays. The proposed research has two specific aims: 1) Define the coordination of uptake and efflux capabilities among individual cells in a community as a function of zinc exposure. 2) Define the relation of periplasmic zinc concentration changes among individual cells in a community upon perturbation of their metal homeostasis. The applicant will be advised by a mentoring team that includes a chemist with expertise in single-molecule spectroscopy of bacterial metal uptake/efflux pumps, a biomedical engineer with expertise in microfluidic systems, and a microbiologist with expertise in bacterial metal homeostasis. The broader impact of this research is the creation of a quantitative model to describe how zinc metal homeostasis is achieved at the community level and delineate the role of the individual cells in a colony in facilitating homeostasis. The significance of this work is the creation of fundamental knowledge for help designing new innovative antimicrobial therapy that utilizes metal homeostasis. .