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(2020) Revealing Biomineralization and SOM-Mineral Associations with Chemical Imaging Methods

Dohnalkova A, Kovarik L, Varga T, Battu AK, Jiao Y, Park D, Marcus M, Krivanek O, Lovejoy T & Kukkadapu R


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06l: Room 2, Thursday 25th June 00:33 - 00:36

Listed below are questions that have been submitted by the community that the author will try and cover in their presentation. To submit a question, ensure you are signed in to the website. Authors or session conveners approve questions before they are displayed here.

Submitted by Marjorie Schulz on Tuesday 16th June 22:58
Hi, Thanks for the informative presentation and beautiful images. Is the Ca imaged near the bacterial cell (2nd experiment) all associated with mineral calcite? If so, is the bacteria is creating biogenic calcite (a phenomenon that is know to occur in several genera of bacteria)? Do you mean to imply that the Ca SOM "bridge" is calcite?
Thanks very much! Yes, I think we’re seeing microbially-induced calcite on the surfaces of the mineral-encrusted bugs. In fact, we see some of the bacteria are encrusted in needle-like crystals which we analyzed by EDS as CaCO3. More analyses like micro-SAD (diffraction) are needed to identify it for sure. I wish I knew more about the Ca bridge; one of the comments was the role of Fe3+-carboxylate and Fe3+-phosphoryl interactions may be also critical here. So it's probably not that simple. Please let me know your thoughts - thank you!

Submitted by Daniel Gregory on Thursday 18th June 16:44
Thank you for the presentation, really interesting talk. I want to ask about your the first part of your talk. Can you describe how long it took to get the REE needles you showed? Also, Do you know what happens as time goes on? Do the needles get larger or do new ones form? Also, is there a point where REEs are no longer removed from the solution?
I asked my LLNL collaborators who ran the expt, and this is their reply : <> On my side, it was the beads infiltration and polymerization before sectioning for TEM. Although all biogenic mineral formation was stopped once the cells were fixed (= killed), there may be a possible abiotic reaction, too. I would like to think it's not happening, as we also had abiotic controls. Please see the paper for more details: Brewer A. Environ. Sci. Technol. 2019, 53, 13888?13897. <> - the intracellular nanocrystalline nucleation in bacteria is an interesting phenomenon, and from our experience, rather than growing larger crystals, they form aggregates that look like larger crystals, but at the high resolution, they are visibly composed of their smaller initial crystals. Thank you!

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