The remarkable diversity of the metabolic pathways of prokaryote organisms has enabled them to exist in a wide range of habitats, including those classed as extreme. Some prokaryotes use light or organic matter to harvest the energy they need, while others use the redox potential of molecules from the surrounding environment and mineral substrates.
Studies into molecular evolution and data from the geological record have revealed that these bioenergetic pathways evolved within the first billion years of life on Earth. Although each pathway has been studied in great detail in isolation, little research has been conducted into how this metabolic diversity evolved.
Further details: Evolution of bioenergetic pathways in prokaryotes