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Paradoxical DNA repair and peroxide resistance gene conservation in Bacillus pumilus SAFR-032

Jason Gioia et al. PLoS One. .

Abstract

Background: Bacillus spores are notoriously resistant to unfavorable conditions such as UV radiation, gamma-radiation, H2O2, desiccation, chemical disinfection, or starvation. Bacillus pumilus SAFR-032 survives standard decontamination procedures of the Jet Propulsion Lab spacecraft assembly facility, and both spores and vegetative cells of this strain exhibit elevated resistance to UV radiation and H2O2 compared to other Bacillus species.

Principal findings: The genome of B. pumilus SAFR-032 was sequenced and annotated. Lists of genes relevant to DNA repair and the oxidative stress response were generated and compared to B. subtilis and B. licheniformis. Differences in conservation of genes, gene order, and protein sequences are highlighted because they potentially explain the extreme resistance phenotype of B. pumilus. The B. pumilus genome includes genes not found in B. subtilis or B. licheniformis and conserved genes with sequence divergence, but paradoxically lacks several genes that function in UV or H2O2 resistance in other Bacillus species.

Significance: This study identifies several candidate genes for further research into UV and H2O2 resistance. These findings will help explain the resistance of B. pumilus and are applicable to understanding sterilization survival strategies of microbes.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Resistance of B. pumilus SAFR-032 spores to UV radiation and H2O2.
a) Survivability of spores exposed to varying doses of UV254 (100 uW sec−1cm−2). Key: B. pumilus SAFR-032, circles; B. subtilis 168, squares; B. licheniformis ME-13-1, triangles. b) Survivability of spores exposed to 5% H2O2 liquid for one hour.
See this image and copyright information in PMC

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