APEX this week with Dr Casey Bryce: Microbial iron oxidation across the Great Oxidation Event...

Our Astrobiology and Planetary Exploration (APEX) seminar this Friday 8th November, at 13:00 GMT, features the following talk:

• Dr Casey Bryce (Bristol): Microbial iron oxidation across the Great Oxidation Event and beyond

The abstract for Casey's talk can be found below.

Please note the day and location for APEX this term: Fridays at lunchtime, 1-2 pm, in room 612 in Birkbeck’s main building on Malet Street.  

A hybrid (in-person and online) format will continue this term but, of course, we warmly encourage in-person attendance to support our visiting speakers.

Details of the forthcoming APEX programme can be found at the link below. The latest information will be advertised in advance of each meeting.  If you are not on our regular mailing lists and are interested in attending these seminars, please contact joanna.fabbri AT ucl.ac.uk.

Abstract

Microbial iron oxidation across the Great Oxidation Event and beyond

Phototrophic Fe(II)-oxidizing bacteria, or “photoferrotrophs”, were probably a key driver of primary productivity and Fe(III) mineral formation in the Earth’s oceans prior to the rise of oxygen. As O₂ began to rise and oxygenate the photic zone, these anaerobic microbes would have seen their habitable space decrease. Furthermore, the transformation from an anoxic to an oxic world would have facilitated an increase in the concentration of oxidized nitrogen species such as nitrate in the oceans. Nitrate-dependent oxidation of Fe(II) is widespread in modern anoxic environments and could, in theory, have competed with photoferrotrophs for Fe(II) in regions where nitrate, light and low-O₂ conditions still co-existed. However, the competition dynamics between these different types of anaerobic Fe(II) oxidation are not well constrained.

Utilizing various co-culture experiments, we have shown that Fe(II) oxidation by photoferrotrophs is not only out-competed but completely inhibited by the activity of nitrate-dependent Fe(II)-oxidizing bacteria. We primarily attribute this inhibition to the observed accumulation of nitric oxide (NO) during denitrification, which is highly toxic at low nanomolar concentrations. These results suggest that the evolution of the nitrogen cycle over the Great Oxidation Event could represent a yet unreported control on the extent of Fe(III) mineral formation by photoferrotrophs in the ancient oceans.     

Links 

• Dr Casey Bryce's academic profile
• APEX programme for this term 
• Recordings of previous APEX talks