On the planet of Arrakis, in Frank Herbert’s novel Dune, giant desert worms roam around the planet leaving the very precious spice behind them. On a scale closer than fiction, earth as its very own the ice worms! And we are going to have a glance at their microbiota in our Microbial advent calendar day 14!
If Dune’s desert worms are giant monsters, the ice worms are extremely tiny. There scientific name being Mesenchytraeus solifugus, and they belong to the Oligochaete subclass of annelid worms. You can mainly find those guys in the snow and ice of glaciers of North America, where allegedly one glacier host more worms than there are humans on earth. The ice worms are popular among geologist and mountaineers which explored those glaciers during the 19th and early 20th century. There is even a poem written by the English poet Robert William Service:
“In the land of the pale blue snow
Where it’s ninety-nine below,
And the polar bears are dancing on the plain,
In the shadow of the pole
Oh, my Heart, my Life, my Soul,
I will meet thee when the ice-worms nest again.”
Beyond the fact that you found those worm only in ice, they actually only can live there, they die if the temperature reaches +10°C and even dissolves at +20°C. They are the extreme example of adaptation to cold environments. It is thought that they feed on snow algae (or Watermelon snow because high concentrations of the algae give the snow a reddish colour) and other microorganisms found in such environments.
In the past few years two studies, from Murakami et al., (here and here) looked at the bacterial populations associated with M. solifugus. First using clone libraries, then with Next Generation Sequencing technology for amplicon libraries, they investigated the 16S rRNA genes associated with the worms. In both cases, they showed that the population associated with the worm are a mix of the bacteria commonly found in Glacier environment but also contain a large portion of bacteria belonging to lineage knows to be associated with invertebrates.
In both cases, they investigated candidate phyla know to make host-microbe associations and showed that the worm gut is likely to host specific bacteria, the “Candidatus Vermiplasma glacialis” (+1 point for a cool name) and other bacteria belonging to the Mollicutes are likely to colonize the worm epithelium. These two studies show that the worm is providing a unique environment for some bacteria to thrive in an otherwise very nutrient-limited environment.
Great thanks to Redwick for his post and finding the poem about the worm. You can find nice picture of the worm on his post on summitpost.