Permafrost with Devin Drown

Episode Summary Dr. Devin Drown, associate professor of biology and faculty director of the Institute of Arctic Biology Genomics Core at the University of Alaska Fairbanks, discusses how soil disturbance gradients in the permafrost layer impact microbial communities. He also explains the larger impacts of his research on local plant, animal and human populations, and shares his experience surveilling SARS-CoV-2 variants in Alaska, where he and colleagues have observed a repeat pattern of founder events in the state. Ashley's Biggest Takeaways

• Permafrost is loosely defined as soil that has been frozen for 2 or more years in a row.
• Some permafrost can be quite young, but a lot of it is much older—1000s of years old.
• This frozen soil possesses large storage capacity for walking carbon and other kinds of nutrients that can be metabolized by microbes as well as other organisms living above the frozen ground.
• About 85% of the landmass in Alaska is underlined by permafrost. Some is continuous permafrost, while other areas of landmass are discontinuous permafrost—locations where both unfrozen soil and frozen soil are present.
• As this frozen resource is thawing as a result of climate change, it is releasing carbon and changing soil hydrology and nutrient composition, in the active layer in the soil surrounding it.
• Changes in the nutrients and availability of those nutrients are also likely changing the structure of the microbial communities.
• Drown and team are using a combination of traditional (amplicon sequencing) and 3rd generation (nanopore) next sequencing (NGS) techniques to characterize the microbes and genes that are in thawing permafrost soil.

Featured Quotes: “Globally, we've seen temperatures increase here in the Arctic. Changes in global temperatures are rising even faster, 2-3 times, and I've heard recent estimates that are even higher than that.” “These large changes in temperatures are causing direct impacts on the thaw of the permafrost. But they're also generating changes in other patterns, like increases in wildfires. We just had a substantial wildfire season here in Alaska, and those wildfires certainly contribute to additional permafrost thaw by sometimes removing that insulating layer of soil that might keep that ground frozen, as well as directly adding heat to the to the soil.” “There are other changes that might be causing permafrost thaw, like anthropogenic changes, changes in land use patterns. As we build and develop roads into areas that haven't been touched by humans in a long time. We're seeing changes in disruption to permafrost.” “Some people are quite interested in what might be coming out of the permafrost. We might see nutrients, as well as microorganisms that are moving from this frozen bank of soil into the active layer.” “We're using next generation sequencing techniques to characterize not only who is in these soils, but also what they're doing.” “I started as a faculty member in 2015. As I moved up to Alaska, I got some really great advice from a postdoctoral mentor that said, make sure you choose something local. I'm fortunate enough that I have access to permafrost thaw gradient, that's effectively in the backyard of my office.” “Just a few miles from campus, we have access to a site that's managed by the Army Corps of Engineers. They have a cold regions group up here that runs a more famous permafrost tunnel. So they've dug a deep tunnel into the side of a hill that stretches back about 40,000 years into permafrost. They also have a great field site that has an artificially induced permafrost thaw gradient, and a majority of our published work has been generated by taking soil cores from that field site.” “Maintaining that cold chain, whether it’s experimental reagents or experimental samples, is a challenge for everyone. We're collecting active layer soil—the soil directly beneath our feet—so that's not at terribly extreme temperatures. But we do put it in coolers immediately upon extracting from the from the environment. Then we can bring it back to our lab where we can freeze it if we're going to use it for later analysis, or we can keep it at appropriately cool temperatures, if we're going to be working with the microbial community directly.” “We were most interested in looking for microbes that might have impacts on the above ground. ecosystem. So when we were characterizing the microbial community, we were doing that because we also wanted to link it to above ground changes.” “Changes in vegetation that might be driven by changes in microorganisms would certainly have an impact on the wildlife that are that are present at the site. So, just as an example, if we see a decrease in berries that might be present, that might decrease the interest from animals that rely on that [food source]. And so we might see changes in who's there.” “Outside of my research, we've seen changes in the types of plants present across northern latitudes. So different willows, for instance, are moving farther north, and that is leading animals, like moose, to move farther north. And so we might see changes in those kinds of patterns directly as a result of the microorganisms as well.” “We're really working to expand our efforts to move to other kinds of disturbances. I mentioned wildfires before, these are an important source of disturbance for boreal forest ecosystems. We have a project here in the interior, looking at the impacts of wildfires on microbial communities and how [these disturbances] might be changing the functional potential of microbial communities.” Let us know what you thought about this episode by tweeting at us @ASMicrobiology or leaving a comment on facebook.com/asmfan.