Sensitivity of a Shiga Toxin-Producing and an Uropathogenic Escherichia coli to UV Irradiation After Freeze-Thaw

Gao, Wa; Leung, Ka Yin

doi:10.1007/s11270-015-2571-7

Cited by 2 publications

(3 citation statements)

References 20 publications

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“…Therefore, it can be said that freezing and thawing in the absence of a cryoprotectant extends bacterial cell longevity in the presence of a known cytotoxic dose of UV irradiation. This phenomenon was also reported by Gao and Leung (2015) where a significant reduction in UV inactivation was observed in cells that had been frozen prior to UVC irradiation (UV fluences of 15 to 90 J/m 2 were used) with E. coli ATCC 25922 showing more UV resistance than the other test organism E. coli O157:H strain 961019 [ 15 ].…”

Section: Discussionsupporting

confidence: 73%

“…As such, this allows for the effects of environmental parameters on non-extremophilic microbes to be examined to determine the upper and lower limits of survival in phenotypically strengthened and weakened bacterial strains. Indeed, E. coli ATCC 25922 was used in a similar set of experiments, as reported by Gao and Leung [ 15 ], using the same 254 nm UV wavelength and the same experimental premise of freeze-thaw, both independently and in combination, thereby allowing comparison with the earlier study. However, in contrast, the current study expands on the findings of Gao and Leung and included harsher test conditions; higher doses of UVC radiation and a greater number of freeze-thaw cycles.…”

Section: Introductionmentioning

confidence: 99%

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The Effects of Freeze-Thaw and UVC Radiation on Microbial Survivability in a Selected Mars-like Environment

et al. 2022

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The purpose of this study was to determine survivability of Escherichia coli, Deinococcus radiodurans and Paraburkholderia fungorum under Mars-simulated conditions for freeze-thawing (−80 °C to +30 °C) and UV exposure alone and in combination. E. coli ATCC 25922, D. radiodurans and P. fungorum remained viable following 20 successive freeze-thaw cycles, exhibiting viabilities of 2.3%, 96% and 72.6%, respectively. E. coli ATCC 9079 was non-recoverable by cycle 9. When exposed to UV irradiation, cells withstood doses of 870 J/m2 (E. coli ATCC 25922), 200 J/m2 (E. coli ATCC 9079), 50,760 J/m2 (D. radiodurans) and 44,415 J/m2 (P. fungorum). Data suggests P. fungorum is highly UV-resistant. Combined freeze-thawing with UV irradiation showed freezing increased UV resistance in E. coli ATCC 25922, E. coli DSM 9079 and D. radiodurans by 6-fold, 30-fold and 1.2-fold, respectively. Conversely, freezing caused P. fungorum to exhibit a 1.75-fold increase in UV susceptibility. Strain-dependent experimentation demonstrated that freezing increases UV resistance and prolongs survival. These findings suggest that exposure to short wavelength UV rays (254 nm) and temperature cycles resembling the daily fluctuating conditions on Mars do not significantly affect survival of D. radiodurans, P. fungorum and E. coli ATCC 25922 following 20 days of exposure.

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Section: Discussionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

The Effects of Freeze-Thaw and UVC Radiation on Microbial Survivability in a Selected Mars-like Environment

et al. 2022

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“…Resistance of E. coli O157:H7 strain 961019 and ATCC 25922 strain to UV radiation increased after freezing and thawing; the ATCC 29522 strain was generally more resistant, but the resistance of the O157:H7 strain 961019 strain increased with increasing freeze-thaw cycles (Gao and Leung, 2015). Zuo, Chu, and Hu (2015) found that ammonia, nitrate and nitrite has little effect on disinfection of MS2 and X174 coliphage in condensate water after the evaporation of source-separated urine for reclaimed water, while disinfection by UV/TiO2 was inhibited by urea and promoted slightly by nitrate and ammonia.…”

Section: Ultraviolet (Uv) Radiationmentioning

confidence: 96%