New avenues for potentially seeking microbial responses to climate change beneath Antarctic ice shelves

• Published in: mSphere
• Main Authors: Llorenç-Vicedo, Aitana, Lluesma Gomez, Monica, Zeising, Ole, Kleiner, Thomas, Freitag, Johannes, Martinez-Hernandez, Francisco, Wilhelms, Frank, Martinez-Garcia, Manuel
• Other Authors: McMahon, Katherine
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society for Microbiology 2024
• Subjects: Antarctic; Ronne Ice Shelf; Antarc*; ice core; Ice Shelf; Ice Shelves
• Online Access: http://dx.doi.org/10.1128/msphere.00073-24; https://journals.asm.org/doi/pdf/10.1128/msphere.00073-24

ABSTRACT The signs of climate change are undeniable, and the impact of these changes on ecosystem function heavily depends on the response of microbes that underpin the food web. Antarctic ice shelf is a massive mass of floating ice that extends from the continent into the ocean, exerting a profound influence on global carbon cycles. Beneath Antarctic ice shelves, marine ice stores valuable genetic information, where marine microbial communities before the industrial revolution are archived. Here, in this proof-of-concept, by employing a combination of single-cell technologiesand metagenomics, we have been able to sequence frozen microbial DNA (≈300 years old) stored in the marine ice core B15 collected from the Filchnner-Ronne Ice Shelf. Metagenomic data indicated that Proteobacteria and Thaumarchaeota (e.g., Nitrosopumilus spp.), followed by Actinobacteria (e.g., Actinomarinales), were abundant. Remarkably, our data allow us to “travel to the past” and calibrate genomic and genetic evolutionary changes for ecologically relevant microbes and functions, such as Nitrosopumilus spp., preserved in the marine ice (≈300 years old) with those collected recently in seawater under an ice shelf (year 2017). The evolutionary divergence for the ammonia monooxygenase gene amoA involved in chemolithoautotrophy was about 0.88 amino acid and 2.8 nucleotide substitution rate per 100 sites in a century, while the accumulated rate of genomic SNPs was 2,467 per 1 Mb of genome and 100 years. Whether these evolutionary changes remained constant over the last 300 years or accelerated during post-industrial periods remains an open question that will be further elucidated. IMPORTANCE Several efforts have been undertaken to predict the response of microbes under climate change, mainly based on short-term microcosm experiments under forced conditions. A common concern is that manipulative experiments cannot properly simulate the response of microbes to climate change, which is a long-term evolutionary process. In this proof-of-concept ...