The desert of Tataouine: an extreme environment that hosts a wide diversity of microorganisms and radiotolerant bacteria.
The phylogenetic diversity of prokaryotic communities exposed to arid conditions in the hot desert of Tataouine (south Tunisia) was estimated with a combination of a culture and - molecular-based analysis. Thirty-one isolates, representative of each dominant morphotypes, were affiliated to Actinobacteria, Firmicutes, Proteobacteria and the CFB group while none related to Archaea. Analysis of 16S rRNA gene libraries revealed the presence of species related to Bacteria and Archaea. Sequences related to Archaea were all affiliated to the non-thermophilic Crenarchaeota subgroup. Bacterial sequences were dominated by Proteobacteria, Actinobacteria and Acidobacteria; a few sequences were distributed among eight others phyla, including Thermus/Deinococcus relatives. A correlation between tolerance to desiccation and to radiation has been demonstrated for the radiotolerant bacteria Deinococcus radiodurans. Because bacteria living in the hot desert of Tataouine are one way or another tolerant to desiccation, we investigate whether they could also be tolerant to radiation. Exposition of soil samples to intense gamma radiation yields Bacillus, Thermus/Deinococcus and alpha-Proteobacteria relatives. Four of these strains correspond to radiotolerant species as revealed by evaluation of the resistance levels of the individual cultures. A detailed analysis of the resistance levels for two Thermus/Deinococcus and two alpha-Proteobacteria relatives revealed that they correspond to new radiotolerant species.
LEMIR, DEVM, DSV, UMR 6191 CNRS-CEA-Université Aix-Marseille II, IFR 112, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France.
Angélique
A
Chanal
Virginie
V
Chapon
Karim
K
Benzerara
Mohamed
M
Barakat
Richard
R
Christen
Wafa
W
Achouak
Frédéric
F
Barras
Thierry
T
Heulin
D020561:Alphaproteobacteria; D001105:Archaea / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000528:radiation effects; D044822:Biodiversity; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D003889:Desert Climate; D003890:Desiccation; D017753:Ecosystem; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D011839:Radiation, Ionizing; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012988:Soil Microbiology; D014416:Tunisia
D019641:DNA, Archaeal; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S