Comparative Metagenomics of the Active Layer and Permafrost from Low-Carbon Soil in the Canadian High Arctic

• Main Authors: Xiaofen Wu (3859054), Archana Chauhan (2302498), Alice C. Layton (1275483), Maggie C. Y. Lau Vetter (10812415), Brandon T. Stackhouse (11377308), Daniel E. Williams (2116630), Lyle Whyte (711992), Susan M. Pfiffner (10812424), Tullis C. Onstott (5423873), Tatiana A. Vishnivetskaya (10812418)
• Format: Other Non-Article Part of Journal/Newspaper
• Language: unknown
• Published: 2021
• Subjects: Microbiology; Genetics; Ecology; Science Policy; Environmental Sciences not elsewhere classified; Biological Sciences not elsewhere classified; reconstructed 91 metagenome; prevalent microbes identified; metagenomes revealed enrichment; main electron acceptor; derived polysaccharide degradation; biodiversity decreased significantly; assembled genomes showed; active layer belonged; showed microbial communities; 5 cm bls; active layer; microbial communities; 65 cm; microbial activity; taxonomic composition; study investigated; study deepen; shock protein; improve prediction; genetic potential; genes encoding; gene abundance; functionally different; contrasting depths; component systems; comparative metagenomics; carbon soil; bacterial taxa; arctic consists; ammonia oxidation; Arctic; permafrost
• Online Access: https://doi.org/10.1021/acs.est.1c00802.s001

Approximately 87% of the Arctic consists of low-organic carbon mineral soil, but knowledge of microbial activity in low-carbon permafrost (PF) and active layer soils remains limited. This study investigated the taxonomic composition and genetic potential of microbial communities at contrasting depths of the active layer (5, 35, and 65 cm below surface, bls) and PF (80 cm bls). We showed microbial communities in PF to be taxonomically and functionally different from those in the active layer. 16S rRNA gene sequence analysis revealed higher biodiversity in the active layer than in PF, and biodiversity decreased significantly with depth. The reconstructed 91 metagenome-assembled genomes showed that PF was dominated by heterotrophic, fermenting Bacteroidota using nitrite as their main electron acceptor. Prevalent microbes identified in the active layer belonged to bacterial taxa, gaining energy via aerobic respiration. Gene abundance in metagenomes revealed enrichment of genes encoding the plant-derived polysaccharide degradation and metabolism of nitrate and sulfate in PF, whereas genes encoding methane/ammonia oxidation, cold-shock protein, and two-component systems were generally more abundant in the active layer, particularly at 5 cm bls. The results of this study deepen our understanding of the low-carbon Arctic soil microbiome and improve prediction of the impacts of thawing PF.