When
Student: Brady Gales, Program in Applied Mathematics
Title: Modeling and Analysis of Multi-Step Bioreactors for Methane Conversion
Advisor: Dr. Ingmar Riedel-Kruse, Department of Molecular and Cellular Biology
Location: MATH 402, Zoom link: https://arizona.zoom.us/j/89982905116 (Password: 12345)
Abstract: New approaches for methane valorization are highly desired for value-added chemical production and greenhouse gas mitigation. At large sources, chemical Gas-to-Liquid conversion suffices, but at smaller, geographically distributed sites it is uneconomical, leaving an opening for low cost biological conversion. Current biotechnology, however, is limited by the carbon and energy inefficiency of aerobic methanotrophs and the unculturability of anaerobic methanotrophs. We address this by proposing two bioreactors that exploit engineered microbial division of labor: the Double Layer Microbial Electrolysis Cell (DL-MEC), a microbial electrochemical cell housing a vertically stratified consortium, and the Longitudinal Partitioned Flow Reactor (LPFR), a membrane-aerated, horizontally partitioned two-stage flow reactor. In both, the methanogen Methanosarcina acetivorans performs anaerobic oxidation of methane (AOM) to acetate, which Escherichia coli aerobically converts to 2,3-butanediol. Modeling the DL-MEC in the electric-potential non-limiting regime, we use global sensitivity analysis to map its operating window and estimate the minimum reaction rates needed to suppress oxygen inhibition. We show that metabolic engineering is required to increase maximum reaction rates for feasibility even under optimized biofilm conditions. Comparing architectures, the DL-MEC achieves higher peak 2,3-butanediol production at equivalent biomass, while the LPFR achieves better volumetric productivity and is compatible with current biotechnology. Together, these models frame the design of aerobic-anaerobic stratified biofilm reactors for product yield from methane oxidation.