Life in the dark

Metagenomic evidence that a microbial slime community is driven by inorganic nitrogen metabolism

Sasha G. Tetu, Katy Breakwell, Liam D H Elbourne, Andrew J. Holmes, Michael R. Gillings, Ian T. Paulsen*

*Corresponding author for this work

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Beneath Australia's large, dry Nullarbor Plain lies an extensive underwater cave system, where dense microbial communities known as 'slime curtains' are found. These communities exist in isolation from photosynthetically derived carbon and are presumed to be chemoautotrophic. Earlier work found high levels of nitrite and nitrate in the cave waters and a high relative abundance of Nitrospirae in bacterial 16S rRNA clone libraries. This suggested that these communities may be supported by nitrite oxidation, however, details of the inorganic nitrogen cycling in these communities remained unclear. Here we report analysis of 16S rRNA amplicon and metagenomic sequence data from the Weebubbie cave slime curtain community. The microbial community is comprised of a diverse assortment of bacterial and archaeal genera, including an abundant population of Thaumarchaeota. Sufficient thaumarchaeotal sequence was recovered to enable a partial genome sequence to be assembled, which showed considerable synteny with the corresponding regions in the genome of the autotrophic ammonia oxidiser Nitrosopumilus maritimus SCM1. This partial genome sequence, contained regions with high sequence identity to the ammonia mono-oxygenase operon and carbon fixing 3-hydroxypropionate/4-hydroxybutyrate cycle genes of N. maritimus SCM1. Additionally, the community, as a whole, included genes encoding key enzymes for inorganic nitrogen transformations, including nitrification and denitrification. We propose that the Weebubbie slime curtain community represents a distinctive microbial ecosystem, in which primary productivity is due to the combined activity of archaeal ammonia-oxidisers and bacterial nitrite oxidisers.

Original languageEnglish
Pages (from-to)1227-1236
Number of pages10
JournalISME Journal
Volume7
Issue number6
DOIs
Publication statusPublished - Jun 2013

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