62
62 2020/2021
ADS8
An international team tracked the genomic composition of microbes in thawing permafrost to determine which had the greatest impact on releases of carbon dioxide and methane into the atmosphere.
Large amounts of soil carbon sequestered in permafrost are becoming available for microbial degradation as permafrost thaws. Its fate is unclear; will it remain stably stored in the soil, or will it be metabolized into the greenhouse gases carbon dioxide or methane? Understanding the carbon processing of microbial communities in thawing permafrost is thus of considerable importance to accurately predicting the magnitude of climate feedback from these systems. However, little is known about these microorganisms because very few can be grown in the laboratory. In this study, a multinational group of researchers applied new sequencing and computational techniques to recover near-complete genomes of microorganisms directly from a permafrost thaw gradient in Stordalen Mire, northern Sweden. Genes encoded on the recovered genomes showed which microorganisms were capable of performing each step of the degradation of soil organic matter, from complex polysaccharides through to carbon dioxide and methane. The correlation of specific lineages indicated potential metabolic cooperation, while other lineages co-varied with the dissolved methane-to-carbon-dioxide ratio, an important parameter in global climate models, and with methane isotopic signatures, a parameter used to partition methane production sources in atmospheric inversion models. Further study is required to elucidate more fully the functions and changes of the microbes, and to distill the insights for use in climate models.
monsters and ghosts of the Russian Arctic
Andra Pop-Jurj
PERMAFROST METABOLISM
