Version 2 2021-09-07, 17:37Version 2 2021-09-07, 17:37
Version 1 2021-09-02, 12:37Version 1 2021-09-02, 12:37
journal contribution
posted on 2021-09-07, 17:37authored byXiaofen Wu, Archana Chauhan, Alice C. Layton, Maggie C. Y. Lau Vetter, Brandon T. Stackhouse, Daniel E. Williams, Lyle Whyte, Susan M. Pfiffner, Tullis C. Onstott, Tatiana A. Vishnivetskaya
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.