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Publications (33)
Background
Extreme terrestrial, analogue environments are widely used models to study the limits of life and to infer habitability of extraterrestrial settings. In contrast to Earth’s ecosystems, potential extraterrestrial biotopes are usually characterized by a lack of oxygen.
Methods
In the MASE project (Mars Analogues for Space Exploration), we...
Five bacterial (facultatively) anaerobic strains, namely Buttiauxella sp. MASE-IM-9, Clostridium sp. MASE-IM-4, Halanaerobium sp. MASE-BB-1, Trichococcus sp. MASE-IM-5, and Yersinia intermedia MASE-LG-1 isolated from different extreme natural environments were subjected to Mars relevant environmental stress factors in the laboratory under controlle...
A critical issue in astrobiology is “where to look for present or past life?” and which types of environments could be relevant, i.e. environments associated with high probabilities to (have) support(ed) life and preserve(d) biosignatures. Due both to the large reservoir it represents and to its protective effect against harmful surface conditions,...
Growth in sodium chloride (NaCl) is known to induce stress in non-halophilic microorganisms leading to effects on the microbial metabolism and cell structure. Microorganisms have evolved a number of adaptations, both structural and metabolic, to counteract osmotic stress. These strategies are well-understood for organisms in NaCl-rich brines such a...
Principal Component Analysis (PCA) plot showing the multivariate variation among the three sample sets (control, NaCl stressed and MgSO4 stressed; n = 3) in terms of the obtained peaks.
List of identified and putatively identified lipids. Metabolite levels for each experimental group are shown. Levels are expressed as mean peak intensity relative to the mean peak intensity of the control group. Numbers indicated in bold indicates statistically significance (p < 0.05).
On a volcanic and anaerobic planet characterized by abundant hydrothermal activity, physicochemical gradients and disequilibria at the local scale would have been fundamental for the emergence of life on Earth. Unfortunately, the early rock record pertaining to this existential process no longer exists, and, while chemists attempt to recreate life...
Phaeobacter leonis strain 306T is an alphaproteobacterium isolated from Mediterranean Sea sediments. It belongs to the genus Phaeobacter, which was recently proposed and is still poorly characterized. In an effort to better understand the fundamental aspects of the microbiology of this genus, we present here the 4.82-Mb draft genome sequence of Pha...
Members of the genus Halomonas are physiologically versatile and harbor ecological adaptations enabling the colonization of contrasted environments. We present here the draft genome of Halomonas lionensis RHS90 T , isolated from Mediterranean Sea sediments. Numerous genes related to stress tolerance, DNA repair, or external signal-sensing systems w...
Subseafloor sediments represent a large reservoir of organic matter and are inhabited by microbial groups of the 3 domains of life. Besides impacting the planetary geochemical cycles, the subsurface biosphere remain poorly understood, notably questions related to possible metabolic pathways and selective advantages that may be deployed by buried mi...
The subsurface realm is colonized by microbial communities to depths of 41000 meters below the seafloor (m.b.sf.), but little is known about overall diversity and microbial distribution patterns at the most profound depths. Here we show that not only Bacteria and Archaea but also Eukarya occur at record depths in the subseafloor of the Canterbury B...
A novel halophilic bacterium, strain RHS90T, was isolated from marine sediments from the Gulf of Lions, in the Mediterranean Sea. Its metabolic and physiological characteristics were examined under various cultural conditions, including exposure to stressful ones (oligotrophy, high pressure and high concentrations of metals). Based on phylogenetic...
The subsurface realm is colonized by microbial communities to depths of >1000 meters below the seafloor (m.b.sf.), but little is known about overall diversity and microbial distribution patterns at the most profound depths. Here we show that not only Bacteria and Archaea but also Eukarya occur at record depths in the subseafloor of the Canterbury B...
Hematite, the most abundant mineral in Iron Oxide Copper Gold (IOCG) deposits in the Gawler Craton of South Australia, may incorporate significant amounts of U, W, Mo and radiogenic Pb. These elements are concentrated in hematite grains which display either oscillatory and/or sectorial compositional zoning, or are porous. The presence of U and Pb r...
A novel Gram-negative, facultative anaerobic, heterotrophic bacterium, designated 306T, was isolated from near surface sediments of the Gulf of Lions, in the Mediterranean Sea. Strain 306T grew at temperatures between 4 and 30°C (optimum 17-22°C), from pH 6.5 to 9.0 (optimum 7.0-9.0) and between 0.5 and 6.0% (w/v) NaCl (optimum 2.0%). Its DNA G+C c...
Relationship between numbers of reads assigned to each
B. prasinos
RCC1105 chromosome based on BLASTX-based analysis of contigs (see Materials and Methods for details) or direct assembly with Geneious.
(TIF)
Percent of false assignment of
O. ‘lucimarinus
’ proteins based on Best BLAST hit (BBH, blue line) or after filtration with gene-specific thresholds for identity and alignment length (FA, red line) as a function of read length (see Materials and Methods for details).
(TIF)
Similarity between specific genes from selected gene classes of
B. prasinos
RCC1105 genome and T142 and T149 Newbler contigs (see Materials and Methods for details).
(PDF)
Assignment of Geneious contigs for samples T142 and T149 to specific chromosomes of B. prasinos RCC1105 based on a BLASTX-based algorithm (see Materials and Methods for details). An estimate of coverage was computed as the ratio between the total length of contigs assigned to one chromosome and the length of this chromosome. This value may exceed 1...
Estimation of the number of major haplotypes and of their frequency for selected regions of genes with a high read coverage in both samples.
(PDF)
Genotype variability within the 5,646 bp rRNA operon. Positions are given along chromosome 11. Localisation of helix 3 of ITS2 follows Marin and Melkonian [39].
(PDF)
Structure of the rRNA operon. (A) Alignment of the B. prasinos RCC1105 rRNA operon (forward copy) with the two contigs T142_109 and T149_486 that contain it. Both contigs do not contain the 433 bp SSU rRNA gene intron that characterizes RCC1105. Contig T149_486 appears to contain a 468 bp intron at the end of the LSU rRNA gene. (B) Detail of the pu...
Assignment of reads and Geneious contigs for samples T142 and T149 to phylogenetic groups based on BLASTN search of a subset of the nr GenBank database, analyzed by MEGAN (see Materials and Methods for details). The contribution of the best represented groups and of the eukaryotic groups expected to be present in the samples are detailed.
(PDF)
Assignment of reads for Pacific picoeukaryote samples T142 to individual chromosomes of
O.’ lucimarinus’
using Geneious Assembler (see Materials and Methods for details).
(PDF)
Genotypic variability of the rRNA operon. T142 and T149 reads were directly assembled with Geneious to the B. prasinos RCC1105 rRNA operon. (A) Individual reads for sample T142 in the region of the SSU rRNA intron present in the genome of RCC 1105. The arrow points to a read with a sequence nearly identical to the intron sequence. (B) Individual re...
SSU rRNA genes detected in Geneious contigs for samples T142 and T149.
(PDF)
Assignment of Geneious contigs for samples T142 and T149 to reference genomes of microalgae, bacteria and viruses based on a BLASTX-based algorithm (see Materials and Methods for details).
(PDF)
List of reference genomes used for BLASTX analysis of contigs.
(PDF)
Among small photosynthetic eukaryotes that play a key role in oceanic food webs, picoplanktonic Mamiellophyceae such as Bathycoccus, Micromonas, and Ostreococcus are particularly important in coastal regions. By using a combination of cell sorting by flow cytometry, whole genome amplification (WGA), and 454 pyrosequencing, we obtained metagenomic d...
