Diurnal Fe(II)/Fe(III) cycling and enhanced O2 production in a simulated Archean marine oxygen oasis

The oxygenation of early Earth’s atmosphere during the Great Oxidation Event, is generally accepted to have been caused by oceanic Cyanobacterial oxygenic photosynthesis. Recent studies suggest that Fe(II) toxicity delayed the Cyanobacterial expansion necessary for the GOE. This study investigates t...

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Bibliographic Details
Published in:Nature communications 2021-04, Vol.12 (1), p.1-11, Article 2069
Main Authors: Herrmann, A. J., Sorwat, J., Byrne, J. M., Frankenberg-Dinkel, N., Gehringer, M. M.
Format: Article
Language:English
Subjects:
631/326/171
704/47
Anoxic conditions
Atmosphere
Cyanobacteria
Cycles
Diurnal
Gas exchange
Green rust
Humanities and Social Sciences
Iron
Marine environment
multidisciplinary
Nocturnal
Oxidation
Oxygenation
Photosynthesis
Pseudanabaena
Rusting
Science
Science (multidisciplinary)
Simulation
Toxicity
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Summary:The oxygenation of early Earth’s atmosphere during the Great Oxidation Event, is generally accepted to have been caused by oceanic Cyanobacterial oxygenic photosynthesis. Recent studies suggest that Fe(II) toxicity delayed the Cyanobacterial expansion necessary for the GOE. This study investigates the effects of Fe(II) on two Cyanobacteria, Pseudanabaena sp. PCC7367 and Synechococcus sp. PCC7336, in a simulated shallow-water marine Archean environment. A similar Fe(II) toxicity response was observed as reported for closed batch cultures. This toxicity was not observed in cultures provided with continuous gaseous exchange that showed significantly shorter doubling times than the closed-culture system, even with repeated nocturnal addition of Fe(II) for 12 days. The green rust (GR) formed under high Fe(II) conditions, was not found to be directly toxic to Pseudanabaena sp. PCC7367. In summary, we present evidence of diurnal Fe cycling in a simulated shallow-water marine environment for two ancestral strains of Cyanobacteria, with increased O 2 production under anoxic conditions. Cyanobacterial photosynthesis is thought to have oxygenated Earth’s atmosphere during the Great Oxidation Event, but these organisms had to overcome the toxic effects of iron. Here the authors simulate Archaean conditions in Cyanobacterial cultures and find that gas exchange and rust formation alleviated iron toxicity.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-021-22258-1