RRC ID 35556
Author Gayán E, Mañas P, Álvarez I, Condón S.
Title Mechanism of the synergistic inactivation of Escherichia coli by UV-C light at mild temperatures.
Journal Appl Environ Microbiol
Abstract UV light only penetrates liquid food surfaces to a very short depth, thereby limiting its industrial application in food pasteurization. One promising alternative is the combination of UV light with mild heat (UV-H), which has been demonstrated to produce a synergistic bactericidal effect. The aim of this article is to elucidate the mechanism of synergistic cellular inactivation resulting from the simultaneous application of UV light and heat. The lethality of UV-H treatments remained constant below ∼45°C, while lethality increased exponentially as the temperature increased. The percentage of synergism reached a maximum (40.3%) at 55°C. Neither the flow regimen nor changes in the dose delivered by UV lamps contributed to the observed synergism. UV-H inactivation curves of the parental Escherichia coli strain obtained in a caffeic acid selective recovery medium followed a similar profile to those obtained with uvrA mutant cells in a nonselective medium. Thermal fluidification of membranes and synergistic lethal effects started around 40 to 45°C. Chemical membrane fluidification with benzyl alcohol decreased the UV resistance of the parental strain but not that of the uvrA mutant. These results suggest that the synergistic lethal effect of UV-H treatments is due to the inhibition of DNA excision repair resulting from the membrane fluidification caused by simultaneous heating.
Volume 79(14)
Pages 4465-73
Published 2013-7
DOI 10.1128/AEM.00623-13
PII AEM.00623-13
PMID 23686270
PMC PMC3697489
MeSH Colony Count, Microbial Escherichia coli / physiology* Escherichia coli / radiation effects* Fluorescence Polarization Hot Temperature Membrane Fluidity Microbial Viability* Ultraviolet Rays*
IF 4.077
Times Cited 25
Prokaryotes E. coli ME9062(BW25113) JW0698-KC JW1625-KC JW4019-KC JW1172-KC JW2669-KC