Do cyanobacteria use iron for photosynthesis?

Dr. Parenteau will speak about her research into the origins of photosynthesis and how this might relate to ancient banded iron formations formed during the great oxidation event. Banded Iron Formations (BIFs) are widespread Precambrian sedimentary deposits that accumulated in deep ocean basins with inputs of reduced iron and silica from deep ocean hydrothermal vents.

There is a large scientific debate as to whether abiotic or biotic mechanisms were responsible for the oxidation of mineral assemblages in BIFs. Biotic oxidation could have occurred as a result of the photosynthetic production of oxygen by cyanobacteria, or could have been directly formed by anoxygenic phototrophs or chemolithotrophs.

Dr. Parenteau has been searching for modern descendants of such an ancestral "missing link" cyanobacterium in the phototrophic mats at Chocolate Pots, a hot spring in Yellowstone National Park. Dr. Parenteau will explain how her study of the biomats using C-14 carbon uptake experiments have tantalizingly showed that the cyanobacteria grow anoxygenically using reduced iron as an electron donor for photosynthesis in situ.

Speaker: Niki Parenteau, SETI