Metal–organic framework micro-nano reactors as armour of Escherichia coli for hydrogen production in air†

Abstract

Hydrogen, as a clean and sustainable energy source, is of great significance in addressing energy crises and environmental issues. Microorganisms such as Escherichia coli (E. coli) are commonly used to produce hydrogen due to their high efficiency, wide choice of substrates, and fast growth rate. However, the hydrogenase in E. coli can only be activated to produce hydrogen under anaerobic conditions, which greatly limits its practical application as a hydrogen producing microorganism. Herein, we report a strategy to construct E. coli@ZIF-8 micro–nano reactors (MNRs), in which the metal–organic framework (MOF) shell serves as armour to provide E. coli with a hypoxic environment that activates hydrogenase and achieves hydrogen production even in air. The MOF shell of the E. coli@ZIF-8 MNR regulates the hydrogen production time by modulating oxygen transport, and thicker MOF shells can effectively delay oxygen diffusion, resulting in faster hydrogen production. Meanwhile, the survival rate of E. coli is improved with the increase of the MOF shell thickness, which is three times higher than that of pure E. coli when cultured in deionized water. This biohybrid system regulates microbial metabolism, which is promising for expanding the applications of microbial hydrogen production.