A team of researchers around SFB PI Prof. Dr. Holger Dau (A4) and Einstein Fellow Prof. Dr. Robert Burnap (Oklahoma, USA) has provided evidence that an evolutionarily ancient version of photosynthesis may be responsible for the formation of Earth's early manganese deposits.

The researchers examined present-day spinach photosystem II particles lacking the manganese-calcium cluster in the presence of dissolved Mn2+ ions. Using optical (UV-visible) and X-ray absorption spectroscopy, they showed that light-driven oxidation of Mn2+ ions resulted in Mn oxide nanoparticles that were bound to the photosystem. These nanoparticles were similar to a mineral rock called birnessite.

The scientists suggest that photosynthetic manganese oxide production in the anoxic environment of the early Earth initiated an efficient cycle of manganese oxide formation and respiration. A gradual transition from manganese oxide nanoparticles to the present-day photosynthetic center, which splits water with only four manganese atoms, now appears as a possible evolutionary pathway.

• DOI: https://doi.org/10.1038/s41467-020-19852-0