Methylmercury in Antarctic Krill Microbiomes.

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Marine food webs can concentrate monomethylmercury (MMHg), a neurotoxin in mammals, in upper trophic level consumers. Despite their remoteness, coastal Antarctic marine ecosystems accumulateand biomagnify MMHg to levels observed at lower latitudes and in the Arctic. Marine sediments and other anoxic habitats in the oceans are typical areas where methylation of mercury occurs and these are likely places where MMHg is being produced. Krill, and more specifically their digestive tracts, may be a previously unaccounted for site where the production of MMHg may be occurring in the Antarctic. If monomethylmercury production is occurring in krill, current views regarding bioaccumulation in the food web and processes leading to the production and accumulation of mercury in the Antarctic Ocean could be better informed, if not transformed. This project will conduct a preliminary assessment of the krill gut microbiomes, the microbiome's genomic content and potential for production of monomethyl mercury by detecting the genes involved in mercury transformations. By analyzing the krill gut microbiome, the project will provide insights regarding animal-microbe interactions and their potential role in globally important biogeochemical cycles. This project will conduct a preliminary assessment of the krill gut microbiomes, the microbiomes genomic content and potential for production of monomethylmercury. The diversity and metabolic profiles of microorganisms in krill digestive tracts will be evaluated using massively parallel Illumina DNA sequencing technology to produce 16S rRNA gene libraries and assembled whole metagenomes. The project will also quantify the abundance and expression of Hg methylation genes, hgcAB, and identify their taxonomic affiliations in the microbiome communities. Environmental metagenomes, 16S rRNA gene inventories produced from this project will provide the polar science community with valuable databases and experimental tools with which to examine coastal Antarctic microbial ecology and biogeochemistry. The project will seek to provide a wider window into the diversity of extremophile microbial communities and the identification of potentially unique and useful bioactive compounds. In addition to public education and outreach. This project will train graduate students and provide educational and outreach opportunities at the participating institutions