Microbial metabolic responses and CO2 emissions differentiated by soil water content variation in subarctic tundra soils

Dockyu Kim, Namyi Chae, Mincheol Kim, Sungjin Nam, Tai Kyoung Kim, Ki Tea Park, Bang Yong Lee, Eungbin Kim, Hyoungseok Lee

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Recent rapid air temperature increases across the northern-latitude tundra have prolonged permafrost thawing and snow melting periods, resulting in increased soil temperature (Ts) and volumetric soil water content (SWC). Under prolonged soil warming at 8°C, Alaskan tundra soils were incubated in a microcosm system and examined for the SWC differential influence on the microbial decomposition activity of large molecular weight (MW) humic substances (HS). When one microcosm soil (AKC1-1) was incubated at a constant SWC of 41% for 90 days (T = 90) and then SWC was gradually decreased from 41% to 29% for another T = 90, the initial HS was partly depolymerized. In contrast, in AKC1-2 incubated at a gradually decreasing SWC from the initial 32% to 10% for T = 90 and then increasing to 27% for another T = 90, HS depolymerization was undetected. Overall, the microbial communities in AKC1-1 could maintain metabolic activity at sufficient and constant SWC during the initial T = 90 incubation. In contrast, AKC1-2 microbes may have been damaged by drought stress during the drying SWC regimen, possibly resulting in the loss of HS decomposition activity, which did not recover even after re-wetting to an optimal SWC range (20–40%). After T = 90, the CO2 production in both treatments was attributed to the increased decomposition of small-MW organic compounds (including aerobic HS-degradative products) within an optimal SWC range. We expect this study to provide new insights into the early effects of warming- and topography-induced SWC variations on the microbial contribution to CO2 emissions via HS decomposition in northern-latitude tundra soil.

Original languageEnglish
Pages (from-to)1130-1138
Number of pages9
JournalJournal of Microbiology
Issue number12
Publication statusPublished - 2022 Dec

Bibliographical note

Funding Information:
This work was supported by Korea Polar Research Institute (KOPRI) grant funded by the Ministry of Oceans and Fisheries (KOPRI PE22130) and National Research Foundation of Korea grant from the Korean government (MSIT; the Ministry of Science and ICT) (NRF-2021M1A5A1065679, NRF-2021M1A5A1075508, and NRF-2021R1I1A1A01053870).

Publisher Copyright:
© 2022, Author(s).

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Applied Microbiology and Biotechnology


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