Skip to main content

On the trail of oxygenic photosynthesis in ancestral Cyanobacteria on early Earth.

While oxygenation of the atmosphere on early Earth is attributed to cyanobacterial oxygenic photosynthesis, the limitations on their expansion is not well understood. Our worked is focussed on assessing the impact of early Earth conditions on ancestral lineages of Cyanobacteria.

Iron is essential for photosynthetic pigment biosynthesis, however the high availability of iron on early Earth contrasts the present-day scenario. We have recently investigated the evolution of iron uptake receptors across the Cyanobacteria and found phylogenetic evidence of commonly occurring uptake mechanisms in the Proterozoic but not the Archaean. The release of oxygen not only alters the redox balance of the environment, it also induces stress on cellular biochemistry by generating oxygen free radicals. We demonstrate that, in a simulated marine environment, deep branching Cyanobacteria undergo less oxidative stress under an anoxic atmosphere than today. Additionally, we demonstrate increased O2 accumulation for aquatic cultures of Cyanobacteria under a 24-hour diurnal cycle compared to a 12-hour cycle. Finally, we show that nitrogen fixation is not restricted under the anoxic, elevated CO2 rich atmosphere of the Archean.

In summary, our research to date suggests that reduced iron acquisition efficiencies may have limited the spread of Cyanobacteria on early Earth, while oxidative stress, does not appear to have been a limiting factor for filamentous strains. Further investigations into the role heterotrophic siderophore iron acquisition within a benthic or free-living community will further elucidate the conundrum of iron limitation in a ferruginous world.


Michelle Martine Gehringer1, Joanne Boden2, Tristan Enzingmüller-Bleyl1, Sadia Tamanna1, Katharina Ebel1, Kimberly Kaiser1, Thorsten Bauersachs3
1Dept. Microbiology, TU Kaiserslautern, Germany; 2School of Earth and Environmental Sciences, St Andrews, UK; 3Institut für Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Kiel
GeoMinKöln 2022
Rheinland Pfalz