Enhanced manganese oxidation at the biofilm−fluid interface drives pore-scale patterns in mineral precipitation

Microbial oxidation of manganese (Mn) from aqueous Mn(II) to solid-phase Mn(III, IV) minerals catalyzes Mn(II) removal in natural and engineered porous systems. However, little is known about the spatiotemporal evolution of Mn biomineralization in confined spaces that experience simultaneous Mn(II) delivery and Mn oxide precipitation. In this work, we combined time-lapse microscopy, image analysis, and mass spectrometry to quantify the extent and rate of Mn biomineralization by Pseudomonas putida GB-1 in an optically transparent two-dimensional porous medium. We conducted microfluidic experiments in triplicate and collected both optical images (color brightfield and mCherry fluorescence) and effluent samples for each replicate. We also developed a calibration curve using optical microscopy and micro-X-ray fluorescence to convert pixel intensity to Mn oxide mass. Images were analyzed with custom MATLAB (2024b) scripts to quantify total Mn oxide accumulation and the rate of mineral precip..., , # Enhanced manganese oxidation at the biofilm-fluid interfaces drives pore-scale patterns in mineral precipitation

### Eleanor C. Fadely^1^, Gaitan Gehin^1^, Sharon E. Bone^2^, Samuel M. Webb^3^, Verónica L. Morales^1^, Jasquelin Peña^1,4^

1. Department of Civil and Environmental Engineering, University of California Davis, Davis, CA 95616, USA.
2. Institute of Bio- and Geosciences: Agrosphere, Forschungszentrum Jülich, Jülich 52428, Germany.
3. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
4. Energy Geosciences Division, Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.

### **Data acquisition**

Microfluidic experiments were set up and run following the methodology outlined in the manuscript main text and supporting information. Color brightfield and mCherry fluorescence images of each microfluidic replicate were collected every 1 h during the experimental growth phase..., ,