The article focuses on the study that has important implications on the establishment of arsenic which occurred on primordial Earth. The findings of the study showed that organisms from such environment may be able to carry out the anoxygenic oxidation of arsenite As(II) to arsenate As(V) that broadens the ecological importance of this phenomenon, and that the production of As(V) by anoxygenic photosynthesis opens a niche for prokaryotes.