Limits...
Phenotypic Characterisation of Shewanella oneidensis MR-1 Exposed to X-Radiation.

Brown AR, Correa E, Xu Y, AlMasoud N, Pimblott SM, Goodacre R, Lloyd JR - PLoS ONE (2015)

Bottom Line: FT-IR spectroscopy of whole cells indicated an increase in lipid associated vibrations and decreases in vibrations tentatively assigned to nucleic acids, phosphate, saccharides and amines.This study suggests that significant alteration to the metabolism of S. oneidensis MR-1 is incurred as a result of X-irradiation and that dose dependent changes to specific biomolecules characterise this response.Irradiated S. oneidensis also displayed enhanced levels of poorly crystalline Fe(III) oxide reduction, though the mechanism underpinning this phenomenon is unclear.

View Article: PubMed Central - PubMed

Affiliation: Williamson Research Centre for Molecular Environmental Science, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom; Research Centre for Radwaste and Decommissioning, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom; School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom.

ABSTRACT
Biogeochemical processes mediated by Fe(III)-reducing bacteria such as Shewanella oneidensis have the potential to influence the post-closure evolution of a geological disposal facility for radioactive wastes and to affect the solubility of some radionuclides. Furthermore, their potential to reduce both Fe(III) and radionuclides can be harnessed for the bioremediation of radionuclide-contaminated land. As some such sites are likely to have significant radiation fluxes, there is a need to characterise the impact of radiation stress on such microorganisms. There have, however, been few global cell analyses on the impact of ionizing radiation on subsurface bacteria, so here we address the metabolic response of S. oneidensis MR-1 to acute doses of X-radiation. UV/Vis spectroscopy and CFU counts showed that although X-radiation decreased initial viability and extended the lag phase of batch cultures, final biomass yields remained unchanged. FT-IR spectroscopy of whole cells indicated an increase in lipid associated vibrations and decreases in vibrations tentatively assigned to nucleic acids, phosphate, saccharides and amines. MALDI-TOF-MS detected an increase in total protein expression in cultures exposed to 12 Gy. At 95 Gy, a decrease in total protein levels was generally observed, although an increase in a putative cold shock protein was observed, which may be related to the radiation stress response of this organism. Multivariate statistical analyses applied to these FT-IR and MALDI-TOF-MS spectral data suggested that an irradiated phenotype developed throughout subsequent generations. This study suggests that significant alteration to the metabolism of S. oneidensis MR-1 is incurred as a result of X-irradiation and that dose dependent changes to specific biomolecules characterise this response. Irradiated S. oneidensis also displayed enhanced levels of poorly crystalline Fe(III) oxide reduction, though the mechanism underpinning this phenomenon is unclear.

No MeSH data available.


Related in: MedlinePlus

Cluster analysis of spectra from irradiated and control cultures of S. oneidensis MR-1.Euclidean distances between cluster centres of control and irradiated sample discriminant function scores extracted during principal component-discriminant function analysis (PC-DFA) applied to (A) FT-IR spectra and (B) MALDI mass spectra of lag, exponential and stationary phase X-irradiated and control cultures. Principal components 1 to 5 (FT-IR) and 1 to 30 (MALDI-MS) were used by the DFA algorithm with a priori knowledge of machine replicates, i.e. 1 class per sample point and treatment, giving 6 classes in total for each dose.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4476702&req=5

pone.0131249.g002: Cluster analysis of spectra from irradiated and control cultures of S. oneidensis MR-1.Euclidean distances between cluster centres of control and irradiated sample discriminant function scores extracted during principal component-discriminant function analysis (PC-DFA) applied to (A) FT-IR spectra and (B) MALDI mass spectra of lag, exponential and stationary phase X-irradiated and control cultures. Principal components 1 to 5 (FT-IR) and 1 to 30 (MALDI-MS) were used by the DFA algorithm with a priori knowledge of machine replicates, i.e. 1 class per sample point and treatment, giving 6 classes in total for each dose.

Mentions: To assess the impact of radiation on the metabolism of S. oneidensis, samples were collected from control and irradiated cultures immediately after irradiation (lag phase), at mid exponential phase and at stationary phase and were analysed by FT-IR spectroscopy. The FT-IR spectra of control and irradiated cultures (12 to 95 Gy) were typical of metabolic fingerprints reported previously for S. oneidensis (S2 Fig) [31]. Inspection of these data by eye is limited as the spectra are qualitatively very similar. Therefore, to observe overall trends in the data and assess the importance of both dose and growth phase on the phenotype of irradiated cultures, PC-DFA was performed on FT-IR data from all growth phases for each separate dose. The Euclidean distances between the cluster centres of control and irradiated samples at each growth phase were measured and are shown in Fig 2. This showed that separation between control and irradiated sample clusters was greatest for lag phase cultures at all doses. Euclidean cluster distances decreased for all further growth phases with a slight increase in distance between the control and irradiated clusters of stationary phase cultures for some doses (12 and 72 Gy). This suggests that changes to the metabolic fingerprint of irradiated cultures are greatest during the lag phase, before the cells have time to recover.


Phenotypic Characterisation of Shewanella oneidensis MR-1 Exposed to X-Radiation.

Brown AR, Correa E, Xu Y, AlMasoud N, Pimblott SM, Goodacre R, Lloyd JR - PLoS ONE (2015)

Cluster analysis of spectra from irradiated and control cultures of S. oneidensis MR-1.Euclidean distances between cluster centres of control and irradiated sample discriminant function scores extracted during principal component-discriminant function analysis (PC-DFA) applied to (A) FT-IR spectra and (B) MALDI mass spectra of lag, exponential and stationary phase X-irradiated and control cultures. Principal components 1 to 5 (FT-IR) and 1 to 30 (MALDI-MS) were used by the DFA algorithm with a priori knowledge of machine replicates, i.e. 1 class per sample point and treatment, giving 6 classes in total for each dose.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4476702&req=5

pone.0131249.g002: Cluster analysis of spectra from irradiated and control cultures of S. oneidensis MR-1.Euclidean distances between cluster centres of control and irradiated sample discriminant function scores extracted during principal component-discriminant function analysis (PC-DFA) applied to (A) FT-IR spectra and (B) MALDI mass spectra of lag, exponential and stationary phase X-irradiated and control cultures. Principal components 1 to 5 (FT-IR) and 1 to 30 (MALDI-MS) were used by the DFA algorithm with a priori knowledge of machine replicates, i.e. 1 class per sample point and treatment, giving 6 classes in total for each dose.
Mentions: To assess the impact of radiation on the metabolism of S. oneidensis, samples were collected from control and irradiated cultures immediately after irradiation (lag phase), at mid exponential phase and at stationary phase and were analysed by FT-IR spectroscopy. The FT-IR spectra of control and irradiated cultures (12 to 95 Gy) were typical of metabolic fingerprints reported previously for S. oneidensis (S2 Fig) [31]. Inspection of these data by eye is limited as the spectra are qualitatively very similar. Therefore, to observe overall trends in the data and assess the importance of both dose and growth phase on the phenotype of irradiated cultures, PC-DFA was performed on FT-IR data from all growth phases for each separate dose. The Euclidean distances between the cluster centres of control and irradiated samples at each growth phase were measured and are shown in Fig 2. This showed that separation between control and irradiated sample clusters was greatest for lag phase cultures at all doses. Euclidean cluster distances decreased for all further growth phases with a slight increase in distance between the control and irradiated clusters of stationary phase cultures for some doses (12 and 72 Gy). This suggests that changes to the metabolic fingerprint of irradiated cultures are greatest during the lag phase, before the cells have time to recover.

Bottom Line: FT-IR spectroscopy of whole cells indicated an increase in lipid associated vibrations and decreases in vibrations tentatively assigned to nucleic acids, phosphate, saccharides and amines.This study suggests that significant alteration to the metabolism of S. oneidensis MR-1 is incurred as a result of X-irradiation and that dose dependent changes to specific biomolecules characterise this response.Irradiated S. oneidensis also displayed enhanced levels of poorly crystalline Fe(III) oxide reduction, though the mechanism underpinning this phenomenon is unclear.

View Article: PubMed Central - PubMed

Affiliation: Williamson Research Centre for Molecular Environmental Science, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom; Research Centre for Radwaste and Decommissioning, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom; School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom.

ABSTRACT
Biogeochemical processes mediated by Fe(III)-reducing bacteria such as Shewanella oneidensis have the potential to influence the post-closure evolution of a geological disposal facility for radioactive wastes and to affect the solubility of some radionuclides. Furthermore, their potential to reduce both Fe(III) and radionuclides can be harnessed for the bioremediation of radionuclide-contaminated land. As some such sites are likely to have significant radiation fluxes, there is a need to characterise the impact of radiation stress on such microorganisms. There have, however, been few global cell analyses on the impact of ionizing radiation on subsurface bacteria, so here we address the metabolic response of S. oneidensis MR-1 to acute doses of X-radiation. UV/Vis spectroscopy and CFU counts showed that although X-radiation decreased initial viability and extended the lag phase of batch cultures, final biomass yields remained unchanged. FT-IR spectroscopy of whole cells indicated an increase in lipid associated vibrations and decreases in vibrations tentatively assigned to nucleic acids, phosphate, saccharides and amines. MALDI-TOF-MS detected an increase in total protein expression in cultures exposed to 12 Gy. At 95 Gy, a decrease in total protein levels was generally observed, although an increase in a putative cold shock protein was observed, which may be related to the radiation stress response of this organism. Multivariate statistical analyses applied to these FT-IR and MALDI-TOF-MS spectral data suggested that an irradiated phenotype developed throughout subsequent generations. This study suggests that significant alteration to the metabolism of S. oneidensis MR-1 is incurred as a result of X-irradiation and that dose dependent changes to specific biomolecules characterise this response. Irradiated S. oneidensis also displayed enhanced levels of poorly crystalline Fe(III) oxide reduction, though the mechanism underpinning this phenomenon is unclear.

No MeSH data available.


Related in: MedlinePlus