Trace gas oxidation genes and metabolism in bacterial communities from a high Arctic mineral cryosol over 13 years
The trace gases carbon monoxide, hydrogen, and methane are important substrates for microbial growth in extreme environments. Evidence has emerged that bacteria in Antarctica and tropical deserts can function as chemoautotrophs by utilizing the energy gained by oxidizing these gases to fix carbon. Trace gas oxidizing bacteria are thought to be important primary producers in polar desert soils and may contribute to nutrient and greenhouse gas cycling, but it is not known how climate change will affect their abundance or activity. In this study, we aimed to determine how trace gas consumption by bacteria has changed over time. We compared metagenomes from high Arctic mineral cryosols obtained in 2011 from Axel Heiberg Island in Nunavut to metagenomes collected from the same site in summer 2024. Using culture-independent approaches, we discovered that the relative abundances of marker genes of trace gas oxidation were predicted with negative effects by soil moisture, which changed significantly over 13 years. In-situ soil gas flux experiments demonstrated that these mineral cryosols acted as sinks for atmospheric methane and hydrogen, but not for carbon monoxide, even though we observed transcripts for carbon monoxide dehydrogenases. We also obtained metagenome-assembled-genomes (MAGs) from the candidate class Ca. Dormibacteria, along with several MAGs capable of both trace gas oxidation and anaerobic respiration, making these organisms interesting candidates forastrobiology and extremophile studies. Our findings uncover metabolic flexibility of trace gas consuming bacteria and indicate that the relative abundance of some Arctic trace gas oxidizing bacteria could be altered by climate-driven changes in moisture.
The trace gases carbon monoxide, hydrogen, and methane are important substrates for microbial growth in extreme environments. Evidence has emerged that bacteria in Antarctica and tropical deserts can function as chemoautotrophs by utilizing the energy gained by oxidizing these gases to fix carbon. Trace gas oxidizing bacteria are thought to be important primary producers in polar desert soils and may contribute to nutrient and greenhouse gas cycling, but it is not known how climate change will affect their abundance or activity. In this study, we aimed to determine how trace gas consumption by bacteria has changed over time. We compared metagenomes from high Arctic mineral cryosols obtained in 2011 from Axel Heiberg Island in Nunavut to metagenomes collected from the same site in summer 2024. Using culture-independent approaches, we discovered that the relative abundances of marker genes of trace gas oxidation were predicted with negative effects by soil moisture, which changed significantly over 13 years. In-situ soil gas flux experiments demonstrated that these mineral cryosols acted as sinks for atmospheric methane and hydrogen, but not for carbon monoxide, even though we observed transcripts for carbon monoxide dehydrogenases. We also obtained metagenome-assembled-genomes (MAGs) from the candidate class Ca. Dormibacteria, along with several MAGs capable of both trace gas oxidation and anaerobic respiration, making these organisms interesting candidates forastrobiology and extremophile studies. Our findings uncover metabolic flexibility of trace gas consuming bacteria and indicate that the relative abundance of some Arctic trace gas oxidizing bacteria could be altered by climate-driven changes in moisture.
Lochlan Breckenridge