Investigating DNA methylation in sea-ice Bacteria

This study aimed to identify whether bacterial sea-ice communities use DNA methylation, and if so, in what way. We sampled sea-ice brines from an Arctic ice-floe in May 2023, using a stepped sackhole brine methods. Samples of sackhole brines were obtained from the top, middle, and bottom of the ice. Brine was filtered onto a 0.2 micron filter at cold temperature, and then flash frozen. The filters were extracted and sequenced using Nanopore. Metagenome assembled genomes were curated after assembly, and reads mapped back onto each MAG to obtain methylation information. We identified methylation motifs then conducted a comparative analysis of each motif's methylation levels across the ice horizons. In tandem with methylation related gene identification and functional annotations, this allows us to assign (or not) a regulatory role to DNA methylation. Motif identification in viral contigs allows us to hypothesize about possible host-phage relationships.