Dietary exposure to toxic metals negatively impacts human health, particularly in early development. These metals are ubiquitous in the diet and current environmental-based remediation strategies are insufficient to tackle this growing problem. As an alternative, we are engineering gut microbes to specifically reduce the bioavailability of mercury through expression of organomercurial lyase: an enzyme which demethylates mercury into a poorly absorbed form. These engineered probiotics could be used as preventative measures in at-risk populations.