Human microbiomes contain a mixed population of bacteria. These bacteria communicate with each other and with the host. Bacteria produce enclosed capsules, called vesicles, that shuttle information (DNA, protein, RNA) between cells and between the bacteria and the host. The communication can affect the types and relative numbers of bacteria present. They can affect the health of the host by stimulating or suppressing immune responses. They impact the local environment, which can also impact reproductive disease resistance, for example. This project is designed to understand bacterial signal production and transmission in a vaginal microbiome. How bacterial vesicles are produced will be investigated. How these capsules move through barriers such as mucus will be evaluated. How they affect the bacterial community composition, and ultimately, health, is of critical importance and will be studied. The project will also provide research experiences for local high school students and undergraduates. This project is designed to advance understanding of how microbiomes contribute to health, with a specific focus on bacterial extracellular vesicles (bEVs). bEVs are a poorly understood mode of cross-kingdom cellular communication. As membrane-bound, nano-sized particles that transport proteins, small molecules, and nucleic acids, bEVs facilitate cellular communication both locally and at distant sites throughout a host. The model system to be studied is the vaginal microbiome. This