To evaluate the habitability of other worlds, we must understand how the early biosphere evolved and developed on Earth and how Earth’s geochemistry impacted those processes. Environmental abundances of redox-sensitive metals such as iron (Fe) and molybdenum (Mo) have shifted over geological history as the Earth’s oceans transformed from largely anoxic to oxic production. This would have impacted microbial processes such as photosynthesis and nitrogen (N) acquisition which rely on bioavailable Fe and Mo, potentially modulating early primary production. I am evaluating whether Archean Ocean concentrations of Mo limit microbial productivity by measuring how Mo additions impact nitrate (NO₃^–) assimilation and Mo uptake among bacteria in Deming Lake which is a modern analog for the Archean Oceans. To address this, I am conducting incubation experiments with isotopically labeled NO₃^– and varying concentrations of Mo to determine whether early N assimilation was limited by Mo. Additionally, I will be doing transcriptomics to measure the microbial response to Mo additions. Expected results will provide insights into the role of Mo in regulating microbial productivity, thereby deepening our understanding of the metal requirements for life, the feedback between life and the environment, and where to search for extraterrestrial life.