Small-Molecule Membrane Engineering Enables High-Performance Biocathode Electrocatalysis via Arginine-Triggered Permeabilization of Escherichia coli

Abstract

Living bioelectrocatalysis holds promise for sustainable energy conversion, yet its performance is often limited by sluggish charge and mass transport across the biotic−abiotic interface. Here, we report a green and programmable small-molecule membrane engineering strategy in which simple arginine functionalization of Escherichia coli (E. coli) controllably increases membrane permeability to construct a high-performance biohybrid biocathode electrocatalyst. The engineered cells deliver an oxygen reduction current density of 3.0 mA cm−2 and enable microbial fuel cells (MFCs) to reach a maximum power density of 194.7 μW cm−2, representing a 6.2-fold enhancement over native E. coli systems. Mechanistic analyses integrating respiration, metabolism, and electrophysiology indicate that arginine-induced permeabilization activates a triple-synergistic regulation: (i) accelerated transport of O2, the terminal electron acceptor, to intracellular catalytic sites; (ii) elevated whole-cell metabolic flux, evidenced by increased NAD+/NADH; and (iii) enhanced secretion of endogenous flavins that facilitates interfacial electron shuttling and reduces charge transfer resistance. This biocompatible molecular membrane engineering route provides a scalable alternative to genetic modification and offers a general platform to unlock microbial electrocatalytic potential for sustainable bioelectrochemical technologies.