In general, the microorganisms you have in your gut today will not be there next month and if they are, they will almost certainly be gone next year. Moreover, the abundance of specific bacteria in the gut changes rapidly over the course of a few days. We are very interested in which factors (host and microbial) influence these dynamics; how this level of change influences human health and disease; and how we can learn from these results to develop novel microbiome-focused treatment and prevention strategies. Check out results from our recent study in healthy humans (Martinson et al. ISME J. In Press).