Bacteria usually have at least one rRNA operon on the chromosome, suggesting that the exclusive presence of rRNA operons on a plasmid is rare and unlikely to be stably maintained. Here, Anda et al. find that at least four bacterial clades in different phyla lost their chromosomal rRNA operons independently, and one of the clades has maintained this peculiar genome organization for hundreds of millions of years.
- Mizue Anda
- Shun Yamanouchi
- Wataru Iwasaki
