Powering up protein: How hydrogel-coated electrodes enhance biohybrid production

Abstract

Integrating water splitting with gas-fixing microorganisms offers a promising route for the sustainable production of chemicals, fuels, and food using renewable electricity. However, challenges such as insufficient gas utilization and undesirable side reactions hinder the scalability of these systems. To overcome these limitations, we proposed and investigated a universal hydrogel-coated electrode strategy to significantly enhance single-cell protein (SCP) production from CO₂ and electricity. The hydrogel coating facilitated the formation of hydrogel-sheared microbubbles of H₂ and O₂, alongside added CO₂, improving gas availability for Cupriavidus necator H16 growth. Additionally, this strategy significantly reduced metal ion release (33.73%-89.32%) and restricted the diffusion of reactive oxygen species (ROS, 87.94%-100%) from the electrodes, both of which previously inhibited bacterial growth and SCP yield. This dual-function coating enhanced both performance and protection across a wide voltage range, leading to a 20.56% increase in biomass production and a 55.96%-166.26% increase in essential amino acid content. With a biomass concentration of 0.96 g/L in a 500 mL bioreactor, this approach demonstrates high scalability and potential for application in various biohybrid electrochemical systems, enabling efficient production of value-added products.