Innovative bioreactor designs for enhancing electron transfer, mass transfer, and product yields in microbial...

Microbial electrosynthesis (MES), a form of bioelectrochemical system (BES) is an emerging versatile platform for the electrobioconversion of CO₂ and diverse array of organic wastes into fuels and chemicals. However, its practical deployment suffers from certain drawbacks, including poor extracellular electron transfer (EET), mass transfer, high internal resistance, and product inhibition. Engineered bioreactor designs can help overcome these limitations. Novel bioreactor designs, such as zero-gap flow reactors, plate reactors, gas diffusion cathodes, porous flow-through, packed-bed electrodes, rotating membrane-less bioreactors, and electrodialysis-integrated devices, have improved current density, electron flux, hydrogen retention, ionic transport, Coulombic efficiency (CE), substrate utilization, and in situ product recovery. This mini review presents recent advances in the design of microbial electrosynthesis bioreactors, with an emphasis on the engineering strategies that enhance electron and mass transport, product titers, and volumetric productivity. Future progress in MES will rely on integrated reactor architectures and separation strategies for carbon-neutral biomanufacturing.