Meet the Winners:

Dr. Kelsey Moore

2023 BioOne Ambassador

BioOne Ambassador Award

How Ancient Microbial Life Shaped the World

What did the Earth look like billions of years ago? And what were the early life forms that shaped the world and set life on its evolutionary trajectory? As a geobiologist, I have spent years trying to answer these questions. I study ancient microfossils preserved in rocks that are hundreds of millions to billions of years old and preserve a record of some of the earliest life forms on our planet. I was always struck by how incredible it was that we can look at rocks like chert – a rock composed of microcrystalline quartz – and see actual bacterial cells that were alive over a billion years ago. We have this beautiful snapshot of ancient life that inhabited the oceans during the Proterozoic Eon – 2.5 billion years ago to 541 million years ago – but I always wondered how this was possible. How did these cells get preserved? How was it possible that minerals could form so quickly around these delicate structures to freeze them in time? These questions set me on a path to better understand that early life and how it may have not only been fossilized, but maybe played a role in its own fossilization.

During my PhD, I tackled my questions through fossilization experiments. Historically, scientists have thought that the process of fossilization that froze those bacterial cells in time was purely abiotic – that it occurred without the help of biology and that the cells were simply innocent bystanders in their own entombment. But I had a suspicion that this might not be true. I hypothesized that the microbes themselves may have had a hand in their own preservation, that they may in some way have contributed to the formation of minerals that preserved them. I tested my hypothesis by incubating living microbes in seawater similar to Proterozoic oceans. After a month of waiting, I was shocked to find that the cyanobacteria had created a sort of “candy coating” of amorphous silica around their cells, preserving the soft organic cells just like the fossils. Oddly, though, the candy-coating of silica was enriched in magnesium, an element that we had not expected. Eventually we were able to untangle the mechanism of fossilization and found that the cells had fossilized themselves through cation bridging. Cell surfaces are often negatively charged, a detail that may seem trivial but in this case is important. Some of the dissolved silica in the water around the cells is also negatively charged in solutions that are slightly basic (typical in seawater). Chemistry and physics tell us that like repels like, so how to you get a negative silica molecule to bind to a negative cell surface? This is where cation bridging comes in. The magnesium cations act as positively charged bridge to bind the silica to the cell surfaces. Through this process, the cells acted as a template to facilitate silica precipitation and their own fossilization.

An example set of BSE images and EDS elemental maps of an organic domain preserved in the freshly fractured surface of the Duck Creek Formation. EDS map overlays show that the carbon (pink) is spatially correlated with the dark region of the BSE image. Overlays of magnesium (blue) and calcium (yellow) reveal cation enrichments in the organic material as faint magnesium and calcium maps that follow the organic carbon as well as bright spots of cation-rich nanophases embedded within the organic domain.
An example set of images showing microfossils and organic matter preserved in ancient chert.

This discovery was exciting because it revealed a possible mechanism to explain those ancient microbial fossils. But there was still something missing. Just because we found one mechanism, how could we be certain that this was the mechanism that occurred billions of years ago? To answer this, we turned to the fossils. We set out to identify evidence that this microbially influenced cation-bridging mechanism in ancient fossils. Using various types of microscopes (light microscopes and scanning electron microscopes (SEM) with energy dispersive x-ray spectroscopy (EDS) we analyzed microfossils and organic matter preserved in ancient chert. And we found exactly the evidence that we had hoped for. The organic matter was enriched in cations and embedded with various nanoscopic cation-rich phases. These cation-organic associations in the chert confirmed that the mechanism that we had identified in our experiments (microbially influenced cation bridging) could explain how microbial cells were preserved in ancient marine environments. You may be asking yourself, why does this matter? Who cares how the cells were preserved? Well, armed with an understanding of how ancient microfossils were preserved, we can begin to address that fundamental question: what did the early Earth and ancient life on our planet look like? Beyond identifying evidence of microbial life in the rock record, we can begin to characterize those ancient microbes and the water chemistry of the ancient oceans in which they lived. Most importantly, we discover that elemental cycles and mineral forming process on the early earth were not purely abiotic. Ancient microbial life did not simply exist in the world, it contributed to shaping the world around it. This holds true not only for the past, but for the present. Microbes are an incredible part of our planet and the more we understand about how microbes contribute to surface processes, the better we can understand the evolution of our planet as a whole in the past, present, and future.

This response is in reference to:

Biosignature preservation aided by organic-cation interactions in Proterozoic tidal environments

PALAIOS, 37(9): 486-498. (2022).
Kelsey R. Moore, Theodore M. Present, Frank Pavia, John P. Grotzinger, Joseph Razzell Hollis, Sunanda Sharma, David Flannery, Tanja Bosak, Michael Tuite, Andrew H. Knoll, Kenneth Williford

Headshot of Dr. Kelsey Moore

Dr. Kelsey Moore

How Ancient Microbial Life Shaped the World

I am a geobiologist with a deep curiosity about the evolution of the Earth. I am particularly interested in how we can use the rock record, fossil record, and experimental fossilization to better understand the evolution of ancient biospheres and how they shaped and were shaped by their environments.

What drew you to the research topic you explored in your submission?

We know that microbes have lived on the Earth for billions of years. Yet we still do not fully understand how early microbes interacted with the world around them and help to shape the planet. My research is driven by my curiosity to understand not only whether or not life existed in various environments throughout Earth history, but also to understand how those ancient microbes interacted with their environments. How did they adapt to and respond to environmental stresses, contribute to geochemical cycles, and facilitate mineral forming processes? By asking these questions, I hope to paint a more complete picture of our young planet and how life and the environment co-evolved through geologic history.

How do you see your work contributing to public policy, citizen science, and/or science education more broadly?

If we can understand how microbes have contributed to geochemical cycles and mineral forming processes throughout Earth history, we gain important insights into the past, present, and future of our planet. This work helps us learn about how our planet and life have evolved over billions of years of Earth history, how life adapts to changing environments, and how microbes contribute to major element cycles in our modern environments. Equipped with this knowledge, we may be able to leverage these microbial-environmental interactions to help the future of our planet. Microbes and mineral formation are key components to the carbon cycle and the processes that sequester carbon (organic or inorganic) and lock it away in rocks may prove useful as we develop new carbon capture and sequestration techniques to draw CO2 out of the atmosphere.

What are your continuing research goals for the future (near and/or far)? What topics, areas, subjects are you interested in exploring?

My future research will build upon my interests and ultimate goal of understanding how the biosphere 1) responded to changing environments through time and 2) contributed to geochemical cycles and sedimentary processes to shape a range of environments throughout Earth history. I will use a combination of geologic field work, analytical analyses of microfossils and biosignatures, and experimental work to address these topics. I hope to also apply these studies as we look to the future and consider novel carbon capture and sequestration techniques.

What are your continuing research goals for the future (near and/or far)? What topics, areas, subjects are you interested in exploring?

In addition to my Earth based research, I am also a member of the Mars2020 mission and am excited to apply my expertise as we search for potential biosignatures on Mars!


Dr. Kelsey Moore

For information about the Society for Sedimentary Geology, please visit their website:

Society for Sedimentary Geology

For questions about BioOne or the BioOne Ambassador Award, please contact:

Amanda Rogers

BioOne Publishing
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