Electrochemical platform of controllable pH gradients in microbial systems

Most microorganisms grow in assemblages with chemical gradients that influence, and are influenced by, metabolism. pH gradient plays an important role in various metabolism processes. Understanding the effects of the pH gradient on metabolism and regulation within microbial assemblages is important for microbial physiology. However, the complexity of the microbial environment makes it hard to decouple the effect of the pH gradient from other species. Therefore, an artificial pH gradient is required to reveal the correlation of the pH gradient and microbial physiology. Here, we demonstrated a controllable pH gradient plate by using electrochemical proton coupled electron transfer reaction based on interdigital electrodes. The morphology design of the interdigital electrodes enables a pH gradient at the level of 10 micrometers, which was demonstrated under confocal microscope with a resolution of 1 micrometer. The electrochemical system also achieved a fast time response of ten seconds. In summary, this platform provided a flexible pH gradient with a high spatial and temporal resolution.