Summer Research Project Seeks to Solve Mystery of Ancient Bacteria
By Zeke Shomler
The sun may be high in the sky, but the academic work doesn’t stop during summer for everyone. I recently spoke with Hannah Woody, an M.S. student in Microbial Ecology, about her summer research project—and I’m here to tell you all the microscopic details.
Hannah and her team have dug up ancient bacteria from the Alaskan permafrost-–some as old as 40 thousand years—and somehow, it’s still alive. Elsewhere, bacteria have been found in permafrost as old as 48,000 years. With barely any nutrients or water, you’d think these microorganisms would very quickly expire, but they seem to have some special metabolic system or dietary habit that keeps them kicking. So, in Hannah’s own words: “how are they surviving 50,000 years on seemingly nothing??”
Alongside her advisor Dr. Mario Muscarella and undergraduate researchers Michelle Ramirez and Tracy Leithauser, Hannah is working hard to answer that very question.
The research starts with collecting “permafrost cores,” long round sections taken from deep beneath the frozen ground. Some of the cores for this project were collected from the Cold Regions Research and Engineering Lab in Fox, while others came from North Campus near Smith Lake.
The cores are then taken back to the lab where the bacteria is isolated and a soil sample is sent away for carbon dating. The frozen permafrost samples need to be carefully sliced and drilled in a sterile environment to keep the bacteria intact and free from contamination.
Once the bacteria are retrieved and isolated, the fun begins. Hannah has spent months in the lab monitoring the carbon usage of these ancient microbes using both an optical oxygen monitor and a chemostat bioreactor, testing different nutrient concentrations and recording the bacteria’s oxygen output. By keeping track of the amount of oxygen they create, Hannah can work backward mathematically to determine how much carbon they’ve used up.
The bacteria are also given radiolabeled Leucine, which is an amino acid used for making proteins. By adding radioactive markers, Hannah and her team can monitor the amount of Leucine that is consumed and incorporated into bacterial proteins during a precise period of time. This helps create a picture of their metabolism to solve the mystery of what these bacteria actually need to survive.
As far as actually solving the mystery? Well, it’s a work in progress. Despite being nearly starved for tens of thousands of years, these little guys are surprisingly picky. Hannah has tried a number of different nutrient combinations, but nothing seems to make the bacteria want to use oxygen any more quickly-–even though you’d expect them to consume lots when they have everything they need.
What actually seems to be happening is a kind of bacterial cannibalism, or “necromass recycling”-–the bacteria appear to be waiting for their fellow microbes to die, and then using the nutrients from the dead cells to respire. It’s possible that this is part of the answer to how they’re able to survive so long in permafrost, but more likely, Hannah says, they’ve been surviving on an extremely specialized diet for such a long time that they don’t want anything else. She’ll have to keep trying different combinations of nutrients, carefully monitoring her equipment, to figure out exactly what makes these guys tick.
Perhaps the most fascinating thing about this research is not the bacteria itself, but what we can learn from it. Hannah’s interest in microbial ecology stemmed from an interest in astrobiology: the search for alien life.
When we look for life on other planets, we’re typically looking in places where we’d expect life to be on earth-–that is, planets with liquid water. But if we can figure out how bacteria are able to live frozen on earth for long periods of time, then that opens up new avenues for finding life elsewhere. As Hannah stated:
“We know that there are icy bodies in our solar system and galaxy that show evidence of having previously had water on the surface that could have supported life. Mars in particular. And other planetary bodies like Europa might have subsurface water. Maybe it is possible that bacterial life developed on one of these bodies while it was warmer and have since been quietly harboring under the surface ice or soils quietly waiting for the next warm period. Studies like this might change the way we look for extraterrestrial life... because maybe a planet doesn't currently need to have surface water to support microbial life!”
Beyond the search for extraterrestrials, this work has powerful implications for the way we think about climate change as well. The bacteria that Hannah studies produce both methane and carbon dioxide, two of the most insidious greenhouse gases. As permafrost thaws due to global warming and releases the nutrients trapped inside, it’s important for us to understand how the bacteria will react. The danger is that they might use up all that carbon to create more greenhouse gases, exacerbating the permafrost thaw problem and causing it to increase exponentially.
Though they’re tiny, these microbes have the potential to pack a big punch to the climate system. Permafrost holds trillions of tons of labile carbon, which is carbon in its most-usable form within the soil-–twice as much as the carbon that’s already in the atmosphere. As the permafrost melts and frees up that easy-to-use carbon, microbes may rapidly turn it into dangerous greenhouse gas. This project is a step toward understanding what exactly that might look like.
But Hannah’s research is far from being all doom and gloom. She’s put her years of education to good use in problem-solving and fine-tuning her experiment, making exciting discoveries in a field where very little research has been done already. “I love that my work has implications for astrobiology,” she stated. “That was always my research goal, and I think this study will help in figuring out whether life outside of Earth exists or not.”
Before coming to UAF, Hannah completed her bachelor degree in genetics and evolution from the University of Montana. Going forward, she hopes to keep working in the field of environmental microbiology and ecology. Her experiences this summer with lab work, field work, data analysis, coding, and research design will undoubtedly be beneficial in her future career.
“Summer research is a tier above in my book,” Hannah said, “because it’s not disrupted with classes and homework. You can pour undivided attention into your project and really get your hands dirty.” She encourages anyone interested in summer research to pursue it: “microbes are really cool, and if people are interested in working with them they should reach out to professors here on campus… there are a lot of funding opportunities here at UAF for both graduate and undergraduate research projects and a lot of ways to get involved with this type of research. You just have to reach out to the labs!”
On behalf of the campus community, we’re excited to see where this research goes.
Thank you for your hard work, Hannah!