Eleanor Fadely

Biogenic manganese (Mn) oxide minerals play a key role in biogeochemical processes in soils, sediments, and water treatment systems. Using a novel microfluidic system, we investigate microbial Mn oxide precipitation in a model porous medium. Our findings offer insights into the mechanisms governing Mn oxidation in natural and engineered environments.

Microbial manganese (Mn) oxidation drives key biogeochemical processes in porous environments. The resulting biogenic Mn oxides influence nutrient cycling in soils and sediments and contaminant immobilization in engineered treatment systems. However, Mn oxide minerals can also oxidize aqueous Mn, which influences their reactivity with organic and inorganic constituents. While microbial Mn oxidation has been studied using batch and column experiments, neither system provides in situ or real-time insights into mineral distribution, precipitation kinetics, or mineralogy. To address this knowledge gap, we have developed a microfluidic platform to investigate pore-scale Mn oxide precipitation by the bacterium Pseudomonas putida GB-1. We integrate this system with optical microscopy and quantitative image analysis to investigate the rate and extent of mineral accumulation under continuous flow conditions. We further apply synchrotron-based X-ray fluorescence spectroscopy to evaluate the evolution of Mn speciation over time. Together, these data provide mechanistic insights into Mn oxide precipitation in dynamic and complex porous environments.