title: Survival of Shewanella oneidensis MR-1 after UV radiation exposure.
abstract: We systematically investigated the physiological response as well as DNA damage repair and damage tolerance in Shewanella oneidensis MR-1 following UVC, UVB, UVA, and solar light exposure. MR-1 showed the highest UVC sensitivity among Shewanella strains examined, with D37 and D10 values of 5.6 and 16.5% of Escherichia coli K-12 values. Stationary cells did not show an increased UVA resistance compared to exponential-phase cells; instead, they were more sensitive at high UVA dose. UVA-irradiated MR-1 survived better on tryptic soy agar than Luria-Bertani plates regardless of the growth stage. A 20% survival rate of MR-1 was observed following doses of 3.3 J of UVC m(-2), 568 J of UVB m(-2), 25 kJ of UVA m(-2), and 558 J of solar UVB m(-2), respectively. Photoreactivation conferred an increased survival rate to MR-1 of as much as 177- to 365-fold, 11- to 23-fold, and 3- to 10-fold following UVC, UVB, and solar light irradiation, respectively. A significant UV mutability to rifampin resistance was detected in both UVC- and UVB-treated samples, with the mutation frequency in the range of 10(-5) to 10(-6). Unlike in E. coli, the expression levels of the nucleotide excision repair (NER) component genes uvrA, uvrB, and uvrD were not damage inducible in MR-1. Complementation of Pseudomonas aeruginosa UA11079 (uvrA deficient) with uvrA of MR-1 increased the UVC survival of this strain by more than 3 orders of magnitude. Loss of damage inducibility of the NER system appears to contribute to the high sensitivity of this bacterium to UVR as well as to other DNA-damaging agents.
authors.affiliation: Center for Microbial Ecology, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Qiu
authors.forename: George W
authors.initials: GW
authors.lastname: Sundin
authors.forename: Benli
authors.initials: B
authors.lastname: Chai
authors.forename: James M
authors.initials: JM
authors.lastname: Tiedje
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D003470:Culture Media; D004249:DNA Damage; D004260:DNA Repair; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D020592:Shewanella / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects*; D013472:Sunlight; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C068631:UvrA protein, E coli; D000251:Adenosine Triphosphatases