Genomic Analysis of Microorganisms That Influence Methylmercury Accumulation in Thawing Permafrost of Old Crow Flats, Yukon, Canada
Abstract
The mobility and chemical form of inorganic mercury which is present in arctic and subarctic permafrost soils may change as temperatures rise due to climate change. Thawing permafrost soils can support the microbiological conversion of inorganic mercury to methylmercury, which is bioavailable and is a bioaccumulative neurotoxin. Various groups of anaerobic bacteria and archaea possess the hgcAB genes required for mercury methylation and it is hypothesized that more groups will acquire this ability due to horizontal gene transfer. Generating an accurate model to predict the rate of mercury methylation remains a challenge as it requires an understanding of both abiotic and microbiological sources of mercury transformations and of environmental conditions which can either promote or inhibit them.
This study aims to assess the microbial community composition from a total of eight samples of active layer soil collected from different permafrost landscape features in Old Crow Flats, Yukon, Canada. They were selected based on chemical analyses which found high methyl- to total mercury ratios (meHg/THg) (10-45%) in active layer samples from a polygon trough, a drained lake basin, and from lake bottoms by two lakeshores where ground thaw caused trees to collapse in the water. To contrast the high meHg/THg found in the degradation features, samples collected just outside the features which had low meHg/THg were also selected. Extracted DNA was sent for shotgun sequencing (2 x 150 bp). Metagenome assembled genomes (MAGs) will be generated for phylogenetic and gene function assignments. Similarities and differences between samples will be assessed to find trends between documented methylation rates, microbial community composition, and hgcAB gene abundance. This study will contribute to the future development of models that are critically needed to predict and mitigate mercury methylation in Old Crow Flats and other vulnerable northern permafrost environments.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.C52D0389T