Micro-photographs of <i>P. phosphoreum</i> ANT-2200 cells by electron microscopy.

<p>Observation at 0.1 MPa (A1 on dehydrated samples, A2 on freeze-dried samples) and 22 MPa (B1 on dehydrated samples, B2 on freeze-dried samples) using SEM and at 0.1 MPa (A3) and 22 MPa (B3) using TEM. Intracellular inclusions are indicated by arrows.</p

Cross diagram of the temperature-pressure dependence of <i>P. phosphoreum</i> ANT-2200.

<p>(A) Extrapolated-contour diagram of the temperature-pressure dependence for both the growth rate (r, h⁻¹) and the maximum population density (K, OD_{600 nm}) for <i>P. phosphoreum</i> ANT-2200. The cross coefficient C_r–K is defined as: 0r–K<1. (B) Standard deviation associated to the C_r–K coefficient. The grey circles indicate parameter values used to extrapolate the contours. Size is proportional to their values. The black circle corresponds to the <i>in situ</i> conditions for the strain. Isolines define zones with same level of values.</p

Example of logistic model fitting empirical growth data of <i>P. phosphoreum</i> ANT-2200.

<p>Experiments were done at pressures of 0.1, 10, 22, 30 and 40 MPa and at temperatures of 13°C and 30°C. The logistic model (line) improves the r and K parameter estimation on empirical growth data (dots). Dashed lines are levels of confidence for the 0.05 and 0.95 quantile curves and the 0.25 and 0.75 quantile curves. Mean +/− standard deviation for growth rate (r, h⁻¹) and maximum population density (K, OD_{600 nm}) parameters are indicated. The dotted frame is the growth curve under optimum pressure and temperature conditions using both r and K parameters. The solid line frame is the growth curve under <i>in situ</i> conditions, at 22 MPa and 13°C. N is the number of replicates done for the same pressure and temperature conditions.</p

Bioluminescence and growth of <i>P. phosphoreum</i> ANT-2200.

<p>(A) Bioluminescence (photons sec⁻¹) of <i>P. phosphoreum</i> ANT-2200 at 0.1 MPa (blue lines) and 22 MPa (red lines). (B) Fitted logistic growth curves for 0.1-MPa experiments (blue lines) and 22-MPa experiments (red lines). The dashed lines represent levels of confidence for the 0.05, 0.95 and 0.25, 0.75 quantile curves. Cell number is estimated using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066580#pone.0066580.e001" target="_blank">equation (1</a>). On (A) and (B) blue and red dotted lines represent the mean time of the bioluminescence peak for both pressure conditions.</p

Relative total fatty-acid composition (%) of <i>P. phosphoreum</i> ANT-2200.

<p>Strain ANT-2200 is grown at 0.1 (black bar) and 22 MPa (grey bar). Others: sum of C17:0, C18:2 and C 19:1 fatty acids; UFA: unsaturated fatty acids; SFA: saturated fatty acids.</p

Comparison of 16S rRNA genes and 16S rRNA transcripts based on T-RFLP analyses from BAL and NEREIS+BAL.

<p>(<b>A</b>) Percentage of Operational Taxonomic Units (OTUs) specific to the 16S rRNA genes (RNA− DNA+) or the 16S rRNA transcripts (RNA+ DNA−), or common to both (RNA+ DNA+). The stars show significant differences obtained by the Duncan test (p-value<0.05) compared to the day 2 value. (B) Relationships between percentage of OTUs common to 16S rRNA genes and transcripts (RNA+ DNA+) with n-alkanes concentrations.</p

Characteristics of the CTRL_270d, BAL_270d, NEREIS_270d and NEREIS+BAL_270d cDNA libraries.

<p>Characteristics of the CTRL_270d, BAL_270d, NEREIS_270d and NEREIS+BAL_270d cDNA libraries.</p

Relationship between microcosm conditions and bacterial phylotypes (phylum level).

<p>(A) Heatmap with double clustering. The microcosm conditions are clustered at the top and bacterial phylotypes are clustered on the left of the heatmap according to their intensity profile similarity. Black corresponds to a higher abundance and white to an absence of taxa. (B) Relative abundance (%) of phylogenetic groups in 16S rRNA libraries from the four incubation conditions at 270 days.</p

Bacterial community structure changes based on the 16S rRNA gene (A) and transcripts (B) for 270 days for the four conditions.

<p>Hierarchical analysis was performed using all replicates but only the average similarity between replicates is represented. CTRL, white circle; BAL, black circle; NEREIS, white triangle; NEREIS+BAL, black triangle. Clusters were formed under the 69.9% threshold.</p

Microcosms’ box design.

<p>Sediments were maintained in such microcosm boxes and subjected to 12-hour tidal cycles, renewing the seawater with each tidal cycle.</p