Scientists at Freie Universität and Einstein Fellow Robert Burnap from Oklahoma have demonstrated that today’s photosystem II can form birnessite-type oxide particles efficiently, thus supporting an evolutionary scenario which involves manganese-oxide production by ancestral photosystems.

The researchers isolated the so-called Photosystem II (PSII) from spinach leaves and removed the four manganese atoms which split water and form atmospheric oxygen in today's photosynthesis. These manganese-free photosystems were used to reconstruct what might have taken place billions of years ago in an early form of photosynthesis.

The interdisciplinary team illuminated a 'green soup' of manganese-free photosystems in the presence of small amounts of manganese ions dissolved in water. They observed that the photosystems form manganese oxide nanoparticles within minutes, with 50-100 manganese atoms per photosystem. These nanoparticles resemble a mineral rock called birnessite. The atomic structure was detected by means of X-ray spectroscopy at BESSY, a large-scale research facility of the Helmholtz-Zentrum Berlin (HZB) in Berlin-Adlershof.

The research results were published in the renowned journal Nature Communications.