Permafrost microbial communities and functional genes are structured by latitudinal and soil geochemical gradients

Abstract

Permafrost underlies approximately one quarter of Northern Hemisphere terrestrial surfaces and contains 25–50% of the global soil carbon (C) pool. Permafrost soils and the C stocks within are vulnerable to ongoing and future projected climate warming. The biogeography of microbial communities inhabiting permafrost has not been examined beyond a small number of sites focused on local-scale variation. Permafrost is different from other soils. Perennially frozen conditions in permafrost dictate that microbial communities do not turn over quickly, thus possibly providing strong linkages to past environments. Thus, the factors structuring the composition and function of microbial communities may differ from patterns observed in other terrestrial environments. Here, we analyzed 133 permafrost metagenomes from North America, Europe, and Asia. Permafrost biodiversity and taxonomic distribution varied in relation to pH, latitude and soil depth. The distribution of genes differed by latitude, soil depth, age, and pH. Genes that were the most highly variable across all sites were associated with energy metabolism and C-assimilation. Specifically, methanogenesis, fermentation, nitrate reduction, and replenishment of citric acid cycle intermediates. This suggests that adaptations to energy acquisition and substrate availability are among some of the strongest selective pressures shaping permafrost microbial communities. The spatial variation in metabolic potential has primed communities for specific biogeochemical processes as soils thaw due to climate change, which could cause regional- to global- scale variation in C and nitrogen processing and greenhouse gas emissions.

Seasonal changes in N-cycling functional genes in sediments and their influencing factors in a typical eutrophic shallow lake, China

“…We aimed to identify the major N-cycling gene families and their key environmental factors. A shotgun metagenome sequencing approach was applied to survey 6 important N-cycling processes and related functional genes ( Supplementary Text S1 ): 1) nitrogen fixation (e.g., nifH, nifD, nifK, vnfG, and vnfH ) ( Jiang et al, 2022 ; Li et al, 2022 ); 2) nitrification (e.g., amoA, amoB, amoC, and hao ) ( Wang et al, 2022 ; Liao et al, 2023 ); 3) denitrification (e.g., nirB, nirS, norC, narI and nirK, and nosZ ) ( Waldrop et al, 2023 ); 4) DNRA (e.g., napA, napB, narG, narH, narI, nrfH, nrtA, nirB, nirD, and nrfA ) ( Jiang et al, 2023 ; Waldrop et al, 2023 ); 5) ANRA (e.g., nasA, nasD, nirA, and nasE ) ( Hu et al, 2023 ; Li et al, 2023 ); and 6) anammox (e.g., nirK and nirS ) ( Tu et al, 2017 ; Wang M. et al, 2023 ; Wang X. et al, 2023 ).…”

Antimicrobial resistance in Arctic soils is mediated by competition and facilitation

“…3, S1-S5; Table S1-S3) may arise from varying initial levels of AMR (including ARG abundance and microbial diversity) as well as inherent variability in soil characteristics between different glacier forefields (16,27,28). It has been hypothesised that the initial microbial diversity in recently deglaciated soils results from spatial variation in the paleoenvironment before and during glacier formation (29). We found clear differences in pioneer soils between Midtre Lovénbreenharboring seven out of the 13 examined ARGs and higher richness (1974 OTUs), and Austre Brøggerbreen -which does not harbour any of the examined ARG and had a lower richness (1152 OTUs).…”

Persistent net release of carbon dioxide and methane from an Alaskan lowland boreal peatland complex

“…With a wetter landscape undergoing permafrost thaw (Jorgenson & Osterkamp, 2005), combined with forecasted increases in precipitation as both rain (Lehmann & Coumou, 2015; Tebaldi et al., 2006) and snow (Euskirchen et al., 2016), CH 4 emissions may rise. This rise may be due to an increase in methanogenesis as plants that transport CH 4 , such as sedges, flourish (Christensen et al., 2004; Turner et al., 2020) or due to other factors such as temperature increases and shifting microbial communities (Waldrop et al., 2023). The magnitude of CH 4 emissions in some boreal peatlands, such as fens and bogs, may also be related to inundation sources, which include spring melt and summer rainfall (Euskirchen et al., 2020; Neumann et al., 2019) as well as possible oxidation by methanotrophs (Zhang et al., 2021).…”