As the planet heats up, researchers have been worried about greenhouse gases emerging from melting Arctic permafrost.
Estimates suggest that by 2100, carbon dioxide and methane emissions from this thawing land might rival those of large industrial nations.
But new insights from Colorado State University hint these predictions could be underestimated.
Microorganisms in frozen northern peatlands, containing nearly half the world’s soil carbon, are currently inactive.
However, when the ground thaws, these microbes will become active, breaking down carbon and releasing gases like carbon dioxide and methane.
This activity, driven by microbial respiration, exposes previously untouched compounds, challenging current climate models and leading to unexpected consequences for greenhouse gas emissions.
Probing the Permafrost in Sweden
Unlocking the relationship between soil microbes and polyphenols has been a long journey for McGivern, who started exploring this topic during her doctoral studies in Wrighton’s lab back in 2017.
Her research was driven by a fundamental question: why should soil microbes, which presumably cannot break down polyphenols without oxygen, behave differently from gut microbes that can do so in an oxygen-free environment?
This question has particular relevance to permafrost soils, which are often low in oxygen.
The curiosity stemmed from observing that gut microbes can break down polyphenols in foods like chocolate and red wine, providing humans with healthy antioxidants.
McGivern found it puzzling why soil microbes, especially in oxygen-poor environments like permafrost, couldn’t perform similar metabolic activities. No previous research had deeply investigated this within soil contexts.
With initial lab experiments providing promising results, confirming that soil microbes could indeed break down polyphenols without oxygen, McGivern and Wrighton decided to take their research to the field.
They gained access to core samples from a well-studied site in northern Sweden, known for its permafrost and soil microbiome research.
Before diving into fieldwork, McGivern had to tackle another challenge. She needed to build a comprehensive database of gene sequences linked to polyphenol metabolism.
This involved meticulously cataloging enzymes known to facilitate this process in cattle, the human gut, and some soils from existing scientific literature.
This extensive database was then used to analyze the gene sequences expressed by microbes in the core samples from Sweden.
In their fieldwork, McGivern and her team discovered that polyphenol metabolism was indeed occurring within the soil cores. Analyzing the gene expressions, they found evidence that genes across 58 different polyphenol pathways were active.
This indicated that not only could soil microorganisms potentially perform this metabolic job, but they were actively expressing the necessary genes in their natural environment.
The findings were significant, yet they left some questions unanswered. For instance, McGivern pointed out the need to understand what factors might limit this microbial process and at what rates it occurs.
This information is vital for predicting the additional greenhouse gas emissions that could result from such metabolic activities in permafrost regions.
Wrighton emphasized the importance of this research in building predictive models to understand and perhaps mitigate climate change impacts.
By fully understanding how these metabolic processes work, scientists aim to develop frameworks and models to better forecast greenhouse gas emissions and their implications on global warming.
This research presents a crucial piece in understanding the complex interactions between microbial activity in permafrost and global climate dynamics.
While the current findings mark a significant stride, ongoing studies are vital to uncover more details about the rates and constraints of polyphenol metabolism in natural settings.
Progress in this area could provide a better foundation for predicting and responding to changes caused by thawing permafrost, contributing to broader efforts to address the climate crisis.
The ultimate goal is to refine models that can predict climate-related changes more accurately.
