There is still much to uncover about these megaplasmids and their role in various environments! Thanks to everyone involved, especially @wshuai.bsky.social who investigated modification/methylation patterns to identify the hosts of these plasmids in the gut microbiome.

Almost 80% of the predicted proteins on the plasmids have hypothetical or unknown annotations by various tools. We used structural predictions to help elucidate some of the major functions including potential virulence, antibiotic resistance, and strategies to overcome bacterial host defences.

Next we used a few tools to search public datasets and found similar megaplasmids in adult guts, chicken guts, and panda guts. These elements are also in wastewater, soil, and hospital sinks. Most interesting to us was their discovery in E. coli and Salmonella enterica isolate genomes.

Here are a few highlights:
We first identified a 1.58 Mbp plasmid in an infant gut metagenome thanks to @pacbio.bsky.social sequencing. The average bacterial genome size in these communities is usually less than 5 Mbp so this was curious to us. We then found similar elements in other infants.