Charles is an environmental microbiologist exploring the structure and function of ecological niches and lifestyles shaped by metabolisms that utilize unique spatial or temporal gradients.

During his doctoral research at the University of California, Davis, Charles identified an anaerobic, urea-dependent energy metabolism in certain members of the Sporosarcina genus. This metabolism plays a crucial role in governing the genus's abundance during Microbially Induced Calcite Precipitation (MICP) — a novel geotechnical engineering technique for rapid, biogenic carbonate cementation of soils. In MICP treatments, offset oxygen and urea cycles create conditions that enable periods of preferential, urea-dependent, anaerobic growth of Sporosarcina spp. that defines their ecological niche and underpins their success in these applications.

As a postdoctoral researcher, Charles investigates how bioclogging and flow redirection within soils can drive pore-scale biochemical heterogeneity that facilitates denitrification, and the subsequent formation of nitrous oxide, despite bulk conditions that are typically unfavorable for such processes. By studying the relationship between flow conditions and feedstock on the temporospatial distribution of biomass and oxygen in microfluidic reactors, his work aims to uncover mechanisms that explain how nominally oxic sediments produce nitrous oxide, a potent greenhouse gas, and deepen our understanding of global nitrogen cycling.