Figure 1.
High-pressure bioluminescence system.
(A) Photography of the high-pressure bioluminescence system and (B) schematic section diagram of the high-pressure bioluminescence tank. PMT: photomultiplier tube; OF: optical fiber; CU: photomultiplier counting unit; T: high-pressure temperature sensor; Tc: Tubing around tank for temperature control connected to a thermo chiller (not shown); Tl: Data logger for temperature sensor; Da: PC for data acquisition of bioluminescence and temperature;
Figure 2.
Example of logistic model fitting empirical growth data of P. phosphoreum ANT-2200.
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, OD600 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 in situ conditions, at 22 MPa and 13°C. N is the number of replicates done for the same pressure and temperature conditions.
Figure 3.
Extrapolated-contour diagram of the temperature-pressure dependence of P. phosphoreum ANT-2200.
The diagrams are plotted for (A) the growth rate (r, h-1) and (B) the maximum population density (K, OD600 nm). The grey circles indicate parameter values used to extrapolate the contours. Size is proportional to their value. The black circle corresponds to the in situ conditions for the strain. Isolines define zones with same level of parameter values.
Figure 4.
Cross diagram of the temperature-pressure dependence of P. phosphoreum ANT-2200.
(A) Extrapolated-contour diagram of the temperature-pressure dependence for both the growth rate (r, h−1) and the maximum population density (K, OD600 nm) for P. phosphoreum ANT-2200. The cross coefficient Cr–K is defined as: 0<Cr–K<1. (B) Standard deviation associated to the Cr–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 in situ conditions for the strain. Isolines define zones with same level of values.
Figure 5.
Micro-photographs of P. phosphoreum ANT-2200 cells by electron microscopy.
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.
Figure 6.
Relative total fatty-acid composition (%) of P. phosphoreum ANT-2200.
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.
Figure 7.
Bioluminescence and growth of P. phosphoreum ANT-2200.
(A) Bioluminescence (photons sec−1) of P. phosphoreum 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 equation (1). On (A) and (B) blue and red dotted lines represent the mean time of the bioluminescence peak for both pressure conditions.