The surprising biochemical degradation pathways wetland microbes use to produce alcohol from organic matter may explain how they also produce greenhouse gases.
As organic matter decomposes, it can form valuable alcohols such as ethanol and isopropanol. Decay also releases greenhouse gases such as methane. Is there a link between these processes? Scientists studied sediments from the Prairie Pothole Region of the northern Great Plains, the tenth-largest wetland ecosystem in the world. Peering into workings at the genetic level, they discovered that diverse microorganisms use uncommon and potentially unique biochemical pathways to produce ethanol and isopropanol in wetland sediments.
Wetlands are the main natural source of methane emissions to the atmosphere. The link between the production of alcohols and emission of this greenhouse gas is murky at best. Scientists predicted that poorly characterized groups of microorganisms called fermenters played a key role. This research helped define the relationship among fermentation, alcohol production, and greenhouse gas emissions.
Using previously gathered sediment samples from the Prairie Pothole Region, scientists from Radboud University in The Netherlands, Colorado State University, and Pacific Northwest National Laboratory overcame many technical hurdles to determine the links among specific microbial genes and their associated biochemical pathways and products for a number of important microbes found in wetlands. Using advanced instrumentation at the Environmental Molecular Sciences Laboratory and Joint Genome Institute, the scientists were able to accurately measure alcohol concentrations, look at the types of microbes in the sediments, determine how they functioned at the genetic level, and identify which pathways they used to change decomposing organic matter into alcohol and gases such as methane and carbon dioxide. Their work suggests that fermentation most likely accounts for production of a range of alcohols and contributes a substantial portion of greenhouse gas emissions. Armed with this scientific knowledge, bioengineers can potentially develop more commercially valuable alcohols for motor fuels and industrial use.
BER Program Manager
U.S. Department of Energy Office of Science, Office of Biological and Environmental Research
Climate and Environmental Sciences Division (SC-23.1)
DOE Environmental Molecular Sciences Laboratory
Colorado State University
This work was supported by the Office of Biological and Environmental Research within the U.S. Department of Energy (DOE) Office of Science, including support of the Environmental Molecular Sciences Laboratory and Joint Genome Institute, both DOE Office of Science user facilities.
Dalcin Martins, P., J. Frank, H. Mitchell, L. M. Markillie, and M. J. Wilkins. “Wetland sediments host diverse microbial taxa capable of cycling alcohols.” Applied Environmental Microbiology 85(12), e00189-19 (2019). [DOI:10.1128/AEM.00189-19]
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