Energetics and Ecological Implications of Bacterial Electron Transport Chains

Energy conservation by the electron transport chain (ETC) is a fundamental cellular process. Utilising membrane-bound protein complexes, the ETC allows cells to conserve chemical energy into proton motive force (PMF), which further drives the production of adenosine triphosphate (ATP) used for cell chemistry. In bacteria, diverse respiratory chain compositions exist, enabling them to adapt and thrive in a variety of habitats. In this mini-review, we discuss the energetic efficiency of bacterial respiratory chains to reveal underlying design principles and further explore its implications in supporting survival of bacteria utilising different energy sources. Particularly, our cross-database analyses suggest that the incorporation of cytochrome bc₁ complexes in ETCs, which enables efficient PMF generation, is associated with the dominant bacterial taxa in global oceans and soil, thus highlighting the ecological significance of ETC energetic efficiency.