Microbial slime curtain communities of the Nullarbor caves
Tetu, S.G., Elbourne, L.D.H., Cronan, A., Holmes, A.J., Gillings, M.R. and Paulsen, I.T.
Summers Engel, A.
Walter de Gruyter GmbH
Berlin and Boston
Microbial life of cave systems. Life in extreme environments
The Nullarbor cave slime communities are comprised of unusual chemolithoautotrophs that utilize multiple nitrogen species in energy metabolism. The communities provide a fascinating example of the adaptability of microbial life, which has successfully occupied a niche that appears to be completely isolated from sunlight or photosynthetically derived carbon. In 2001, Holmes and colleagues applied up-todate molecular methods to examine the phylotypic structure of this community. The f indings at that time provided the first glimpse into the ecology of this rare system . A little more than 10 years later, biologists can make use of a range of new technologies to take an increasingly in-depth look into the ecology, taxonomy, and metabolic composition of these unusual and complex communities. Next generation sequencing technologies used to carry out shotgun metagenomic and large scale 16SrRNA amplicon sequencing have revealed fascinating insights into the taxonomically diverse community within Weebubbie Cave. Metagenomic sequencing allowed us to look directly for genes relating to nitrogen cycling in this community and indicated that both stages of nitrification are likely key to energy generation in this community. As such, the Weebubbie Caves slime curtains represent a diverse assemblage of chemolithoautotrophic bacterial and archaeal communities driven by nitrification. However, a number of questions remain to be explored:– Howsimilararemicrobialslimecommunities,bothwithinandbetweenNullarbor cave systems?– Howdochangesinthemicrobialcommunityreflectthevariationsinwaterchemistry observed between the caves?– Canalinkbemadebetweenthemorphotypesobservedviamicroscopyandthe phylotypes detected via DNA sequencing?– Canweexperimentallyconfirmthecarbonandnitrogencyclingmodelspredicted from the metagenomic data?– Aretheseextensivemicrobialcommunitiesabletosupportanimalcommunities? Additional sampling expeditions in these cave systems should provide further insight into these interesting chemolithoautotrophic assemblages.