Fluence rate as a determinant of synergistic interaction under simultaneous action of UV light and mild heat in Saccharomyces cerevisiae

Петин, В.Г.; Zhurakovskaya, Galina P.; Komarova, Ludmila N.

doi:10.1016/s1011-1344(96)07449-0

Cited by 29 publications

(29 citation statements)

References 24 publications

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“…The synergistic interaction of UV light and hyperthermia is expected to result in additional damage due to the interaction of some sub-lesions induced by both agents (Petin et al, 2000(Petin et al, , 1997Tyrrell, 1976). Lower temperatures during UV-B radiation will result in a decrease of synergism (Petin et al, 1997), therefore, causing less damage in the cells.…”

Section: Resultsmentioning

confidence: 99%

Cold activity and tolerance of the entomopathogenic fungus Tolypocladium spp. to UV-B irradiation and heat

Santos

Dias

Ferreira

et al. 2011

Journal of Invertebrate Pathology

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Section: Resultsmentioning

confidence: 99%

Cold activity and tolerance of the entomopathogenic fungus Tolypocladium spp. to UV-B irradiation and heat

Santos

Dias

Ferreira

et al. 2011

Journal of Invertebrate Pathology

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“…The same batch test configurations were used as the control experiments, to ensure comparability among the conditions. Many authors have demonstrated that there is a synergistic action between light and temperature in different media and microorganisms [2][3][4]22,27]. This test investigates the lighttemperature interaction in synthetic secondary effluent.…”

Section: Tablementioning

confidence: 99%

The antagonistic and synergistic effects of temperature during solar disinfection of synthetic secondary effluent

Giannakis

Darakas

Escalas-Cañellas

et al. 2014

Journal of Photochemistry and Photobiology A: Chemistry

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a b s t r a c tA 4-factor, multilevel, full factorial design of 240 experiments was performed in order to investigate the effect of temperature on the inactivation efficiency of spiked Escherichia coli in simulated solar disinfection of a synthetic secondary effluent. The initial population of the microorganisms was 10 3 , 10 4 , 10 5 and 10 6 CFU/mL, the exposure time 1, 2, 3 and 4 h, the treatment temperature 20, 30, 40, 50 and 60• C and the sunlight intensity 0, 800 and 1200 W/m 2 . Radical changes in bacterial behavior, process efficiency and remaining populations were observed, while treating effluents in discreet temperatures. Elevating treatment temperature from 20 to 40• C drastically impaired disinfection. Thermal inactivation with no regrowth predominated at 50• C and total inactivation of microorganisms was observed at 60• C in nonirradiated samples. Irradiation at 800 and 1200 W/m 2 much increased inactivation efficiency, especially at 50 and 60• C, proving sensitive light-temperature synergy at those temperatures. Total inactivation was achieved within 4 h under a range of treatment conditions, including all samples at 1200 W/m 2 , or 60• C samples at 800 W/m 2 . Also, 99.9-100% efficiencies and final population below 1000 CFU/100 mL were obtained at 800 W/m 2 and temperatures of 50 • C and above. Treatment time, temperature and intensity are the critical parameters for the disinfection process, while initial population is insignificant for removal efficiency. An explanation of the mechanism of the process as well as a general linear model predicting the outcome of the experiments is also suggested.

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“…To overcome this limitation, new processes have been designed by combining several technologies applied at lower intensities, but with equivalent or even higher degrees of stability and safety. The interactions of UV light applied simultaneously with chemical agents (8,9,10) and with different energies, such as ionizing radiation (11) and heat (12)(13)(14), have been reported. Regarding the latter, there is an increased interest in the potential use of UV light combined with mild heat (UV-H treatments) for pasteurization of high-UV-absorptivity liquid foods (15), as this combination has been demonstrated to have a synergistic lethal effect on Escherichia coli (12) and Salmonella enterica subsp.…”

mentioning

confidence: 99%

“…enterica serovar Typhimurium (16) at temperatures around 50 to 60°C. Petin et al (14) suggested two possible explanations for the synergistic lethal effect of the combined process, which are not contradictory: the reduction of cellular capacity to repair DNA damage by thermal effects and the interaction of sublethal lesions induced by each of the agents. Despite being of interest, the mechanism of microbial killing improvement by UV light in combination with mild heat is not known.…”

mentioning

confidence: 99%

Mechanism of the Synergistic Inactivation of Escherichia coli by UV-C Light at Mild Temperatures

Gayán

Mañas

Alvarez

et al. 2013

Appl Environ Microbiol

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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 ϳ45°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. U V-C light is an emerging disinfection technology for water and, more recently, for liquid foods due to its multiple advantages (1, 2). UV-C (220 to 300 nm) has a germicidal effect for most types of microorganisms because it produces photochemical modifications of nucleic acids' pyrimidine bases. The major UVinduced DNA lesion is cyclobutane pyrimidine dimers (CPDs), while (6-4) photoproducts (6-4PPs) are also formed on about 25% of CPDs (3). These lesions prevent the proper replication and transcription of DNA, resulting in mutagenesis and, ultimately, cell death (4). The magnitude of the lethal effect depends on the radiation dose and on the cells' ability to repair damage.Microorganisms have adopted various enzymatic DNA repair pathways to restore DNA molecules from replication errors and the action of both endogenous and exogenous DNA-damaging agents. The DNA repair pathways involved in damage repair prior to replication include photorepair, base excision repair (BER), and nucleotide excision repair (NER) (3, 4). Under extensive DNA damage, repair mechanisms controlled by the SOS regulon, such as RecA-mediated excision repair (RAMER), translesion synthesis (TLS), and homologous recombination (HR) repair, are induced (4, 5). Overall, the lethality of UV light could be improved by impairing bacterial DNA repair mechanisms.The ability of UV light to be used for liquid food hygienization has been widely demonstrated (2, 6). In fact, UV-based technologies have been approved as alternative treatments to thermal pasteurization of fresh juice products (7). However, the implementation of UV processing in the food industry is still limited due to ...

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Fluence rate as a determinant of synergistic interaction under simultaneous action of UV light and mild heat in Saccharomyces cerevisiae

Cited by 29 publications

References 24 publications

Cold activity and tolerance of the entomopathogenic fungus Tolypocladium spp. to UV-B irradiation and heat

Cold activity and tolerance of the entomopathogenic fungus Tolypocladium spp. to UV-B irradiation and heat

The antagonistic and synergistic effects of temperature during solar disinfection of synthetic secondary effluent

Mechanism of the Synergistic Inactivation of Escherichia coli by UV-C Light at Mild Temperatures

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