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In this study, the endospores of isolated spore-forming bacteria from a growing …


Biology Articles » Astrobiology » Survival of Spacecraft-Associated Microorganisms under Simulated Martian UV Irradiation » Figures

Figures
- Survival of Spacecraft-Associated Microorganisms under Simulated Martian UV Irradiation

Figures

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FIG. 1. Spectral irradiance plots for the JPL solar simulator (dashed line) and the KSC simulator (solid line). Also included for reference are spectral irradiance plots for the Opportunity landing site under a high sun angle and sky conditions producing optical depths of 0.24 ({lozenge}) and 0.74 ({square}) and irradiance plots predicted for latitude 45°S under a low sun angle and optical depths of 0.24 ({circ}) and 0.74 ({triangleup}).

Figure 1

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FIG. 2. Phylogenetic tree of the type strains of Bacillus spp. used in this study based on maximum-likelihood parsimony analysis of the 16S rRNA gene nucleotide sequences. The numbers after the names of the bacteria are GenBank nucleotide sequence accession numbers. The numbers above the lines are the bootstrap percentages for 500 replications of the branches of the tree.

Figure 2

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FIG. 3. Effect of Mars UV irradiation (JPL simulator) on hydrated spores of select Bacillus species. {blacksquare}, B. pumilus SAFR-032; •, B. megaterium ATCC 14581; {triangledown}, B. subtilis 168. The error bars indicate the standard deviations of three replicate samples. N/No, number of survivors/original number.

Figure 3

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FIG. 4. Influence of various Mars UV spectra on the survival of B. pumilus SAFR-032 spores in water (JPL simulator). •, UVA; {triangledown}, UVA+B; {blacksquare}, full UV spectrum. The error bars indicate the standard deviations of three replicate samples. N/No, number of survivors/original number.

Figure 4

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FIG. 5. Effect of B. pumilus SAFR-032 on spores susceptible to UV-induced inactivation (JPL simulator). {blacksquare}, B. subtilis 168 in mixture; {triangledown}, B. subtilis 168 alone; •, B. pumilus SAFR-032 alone. In the mixed samples equal amounts of spores from the two species were mixed to obtain a total spore density of 106 spores ml–1. The error bars indicate the standard deviations of three replicate samples. N/No, number of survivors/original number.

Figure 5

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FIG. 6. Effect of UV254 irradiation on vegetative cells. {blacksquare}, B. pumilus SAFR-032; •, A. radioresistens; {blacktriangledown}, B. subtilis 168. The error bars indicate the standard deviations of three replicate samples. N/No, number of survivors/original number.

Figure 6

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FIG. 7. Effect of Mars UV irradiation, projected from the KSC simulator, on the spores of B. pumilus SAFR-032 ({blacksquare}) and B. subtilis 168 ({blacksquare}) in water. (A) Full UV spectrum; (B) UVA+B; (C) UVA. The error bars indicate the standard deviations of three replicate samples. N/No, number of survivors/original number.

Figure 7

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Source: Applied and Environmental Microbiology, December 2005, p. 8147-8156, Vol. 71, No. 12


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