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Griffith University (2001)

The Phylogeny of Prokaryotes Associated with Australia’s Great Basin

Spanevello, Mark D.

Titre : The Phylogeny of Prokaryotes Associated with Australia’s Great Basin

Auteur : Spanevello, Mark D.

Université de soutenance : Griffith University.

Grade : Doctor of Philosophy PhD 2001

Résumé partiel
The Great Artesian Basin of Australia is the largest freshwater artesian basin in the world. It underlies arid and semi-arid regions of Queensland, New south Wales, South Australia and the Northern territory, approximately 20% of the Australian continent. Temperatures of its’ waters range from 30 degrees C to over 100 degrees C and over 5000 bores access its waters and empty into open drainage systems for agricultural irrigation and stock watering purposes. The Great Artesian Basin of Australia has great economic and agricultural importance, but prokaryotic communities persisting in the bore waters influence its’ quality. — To gain an understanding of these prokaryotic communities, a culture-independent study was conducted on microbial communities present in the outflow of the New Lorne bore (registered bore number 17263). Five distinct prokaryotic communities existing at different temperatures (88 degrees C, 75 degrees C, 66 degrees C, 57 degrees C, and 52 degrees C) were selected and total genomic DNA was extracted. PCR-amplified 16S rRNA genes were subsequently cloned and a total of 64 clones from the 88 degrees C community and 96 clones from the other communities were examined. Partial sequences identified phylotypes that were then fully sequenced and analysed phylogenetically. The analysis revealed identical phylotypes existing in adjacent communities, as well as an increase in the phylogenetic diversity as water temperature decreased. Sequences identified belonged to species spanning the full diversity of the Bacterial domain, including Hydrogenobacter, Thermus, Meiothermus, Chloroflexus, Cytophaga, Planctomycetes, Rhodothermus, Bacillus, Clostridium, Nitrospira, Verrucomicrobium, Acidobacterium, alpha-, beta-, gamma-, and delta-Proteobacteria. Clones recovered also grouped with taxa with no isolated representatives. Of the libraries, 24 phylotypes from 6 phyla had a similarity of 96% or more to cultured isolates and comprised 73% of all clones analysed. 34 phylotypes from 11 phyla had less than 96% similarity to cultured isolates, or were related to previously cloned 16S rRNA gene sequences, and comprised 27% of the clones analysed. This shows the prokaryotic ecology of the Great Artesian Basin environment includes a diverse range of many uncultured, novel species. — Previous studies on isolates of Thermus and Meiothermus have revealed a relationship between the taxonomic groups and the geographical sites of isolation. A survey of 14 Thermus and 2 Meiothermus isolates and 16S rRNA gene clone data from the New Lorne bore extends the geographical diversity of these two genera. Thermus was isolated from all four mat samples and were most dominant in the red mat at 66 degrees C. Meiothermus was only isolated from the red mat at 66 degrees C. 16S rRNA gene sequence analysis revealed that 13 of the 14 Thermus isolates were closely related to T. igniterrae (100% similarity) and one isolate was closely related to Thermus strain SRI-96 (99.1% similarity). Both Meiothermus had 100% similarity with Meiothermus ruber.

Mots clés : Thermophiles • Great Artesian Basin • phylogeny • thermus • bacteria • microbiology • molecular biology

Présentation (National Library of Australia)

Page publiée le 4 mars 2006, mise à jour le 7 juillet 2017