SGER: Isolation and Culture of Deeply Divergent, Mesophilic Rhizosphere Crenarchaeota

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

A grant has been awarded to Dr. Holly M. Simon at the University of Wisconsin to isolate and culture members of an unusual and little-understood group of soil microorganisms that colonize plant roots. These microbes, known as mesophilic crenarchaeota, are members of the archaea, a third domain of life separate from bacteria and eukaryotes. Growth of archaea on plant roots will be exploited by using the root as a starting point for their growth in vitro. Metabolic differences between archaea and bacteria will be used to selectively enrich for growth of the archaea while discouraging growth of bacteria also present on roots. DNA will be recovered for analysis of the diversity and potential metabolic activities of the assemblages present, which will in turn inform enrichment strategies. While isolation of the root-colonizing archaea in pure culture is the goal, their growth in vitro may require the presence of (an)other organism(s). Discovery of such commensal relationships would represent significant advancement of our knowledge about this unusual group of archaea. Members of the archaea are important contributors to biosphere processes. Examples include the production of methane, (a "greenhouse gas), and globally significant transformations of sulfur. Archaea have also have often been discovered in extreme environments, such as Yellowstone hot springs, or submarine hydrothermal vents. The group of archaea being investigated in this proposal was completely unknown a decade ago. They represent evolutionarily divergent members within the archaeal division Crenarchaeota that are able to grow under moderate (mesophilic) temperature conditions. The isolation and growth in vitro of members from this enigmatic group of archaea will help us understand their place in the scope of archaeal evolution, and will provide insight into their metabolisms and ecological functions.