Identifying uncultivated microorganisms in polar environments

Abstract

Polar regions are often characterized as the coldest, driest, and/or windiest habitats for life on Earth. Even under such extreme conditions, however, microorganisms exhibit remarkable phylogenetic and functional diversity. Our group has studied the microbiomes of Antarctic lake environments. Algae and cyanobacteria often develop luxuriant multi-layered mat consortia in lake bottoms. In association with such mats, aquatic mosses sometimes form unique tower-like structures called “moss pillars” in the freshwater lakes located near Syowa Station, East Antarctica. Moss pillars harbor a high diversity of microorganisms, including both bacteria and eukaryotes, but not archaea. Unexpectedly diverse eukaryotic phylotypes affiliated with algae, ciliates, fungi, nematodes, rotifers, and tardigrades, as well as unclassified phylotypes, have been detected in these pillars. This mini review provides an overview of Antarctic terrestrial ecosystems. Additionally, it presents a brief introduction to an emerging novel cyanobacterial species related to the primitive cyanobacterium Gloeobacter, an unexpected freshwater lineage of Labyrinthulomycetes (fungus-like protists), and uncultivated ultra-small bacteria. Exploration and mining of polar microorganisms would provide great insights into the diversity of life on this planet.