U.A. Bliznyuk1, P.Yu. Borshchegovskaya2, O.V. Yesaulova3, V.S. Ipatova4, V.S. Kim5, S.V. Kuzmin6, A.M. Nasibov7, Z.K. Nikitina8, S.I. Nikiforov9, V.V. Rozanov10, A.P. Chernyaev11, D.S. Yurov12, I.A. Rodin13

1,2,5,10,11,13 Lomonosov Moscow State University (Moscow, Russia)

1,2,4,11,12 Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University (Moscow, Russia)

3,6,9 Federal budgetary establishment of science "F.F. Erisman federal scientific center of hygiene" of the federal service for surveillance on consumer rights protect ion and human well-being (Moscow, Russia)

7,8,10 All-Russian Scientific Research Institute of Medicinal and Aromatic Plants (Moscow, Russia)

13 Department of Epidemiology and Evidence-Based Medicine, Ivan Mikhaylovich Sechenov First Moscow State Medical University (Moscow, Russia)

1 uabliznyuk@gmail.com, 2 alexeevapo@mail.ru, 3 esaulova.ov@fncg.ru, 4 ipatova.vs15@physics.msu.ru, 5 ivantcova.vs20@physics.msu.ru, 6 kuzmin.sv@fncg.ru, 7 El-one-1@mail.ru, 8 nikitinaz@yandex.ru, 9 Nikiforov.si@fncg.ru, 10 vrozanov@mail.ru, 11 a.p.chernyaev@yandex.ru, 12 d_yurov@mail.ru, 13 igorrodin@yandex.ru

When conducting studies on the effect of ionizing radiation on the survival of microorganisms in different environments, special attention is paid to the physical parameters of exposure. However, microorganisms and tissues have different radiosensitivity, therefore, when planning radiation treatment of biological objects, it is important to take into account not only the physical parameters, but also the characteristics of the irradiated biological object itself.

The aim of this study was to investigate the effect of radiation treatment with low-energy electrons with an energy of 1 MeV on the survival rate of Escherichia coli bacteria.

The effect of irradiation with accelerated electrons with an energy of 1 MeV on the survival rate of Escherichia coli bacteria was studied. Irradiation of suspension samples with initial concentration of bacteria (3.6 ± 0.3)-105 CFU/g was carried out at doses of 250 Gy and 1000 Gy. The dose absorbed by the samples was assessed using Fricke's dosimetric solution. Bacterial suspensions irradiated in liquid thioglycol medium immediately after radiation treatment were placed in a refrigerator and stored at 4oC for 18 days. Every three days, irradiated bacteria were sown on solid thioglycol medium with agar in Petri dishes and after two days of incubation at 37oC, colony-forming units (CFU/g) were counted.

As a result of the experiments, the dependences of the concentrations of viable microorganisms on the absorbed dose and on the time of subsequent storage were obtained. Calculation of Log10(N/N0) dependence on the absorbed dose made it possible to estimate the dose required to suppress the viable population by a factor of 10 (D10 = (0.40 ±0.04) kGy). Based on the classical population model, the dependence of the number of bacteria in suspensions irradiated at different doses on the storage time in thioglycol medium was represented as: N(t,D)=N0 e-kD eεt, where N – number of viable bacteria, N0 – initial concentration of bacteria in the control unirradiated suspension, k – number of bacteria inactivated per unit dose, D – irradiation dose, t - sample storage time and ε - bacterial growth factor (difference between the rate of multiplication and the rate of cell death). he values of bacterial growth reduction rates were (210 ± 40) CFU/(g∙day), (300 ± 20) CFU/(g∙day) and (310 ± 40) CFU/(g∙day) for unirradiated samples and those irradiated at doses of 250 Gy and 1000 Gy, respectively.

A nonlinear decrease in the concentrations of viable bacterial cells from the dose immediately after irradiation was established. During subsequent storage of bacterial suspensions, an exponential decrease in the concentration of Escherichia coli bacteria was observed in both non-irradiated and irradiated samples. The values of the rates of decrease in the number of viable cells in irradiated samples exceeded the same values in non-irradiated bacterial suspensions by about 1.5 times.

It is shown that the combined effect of ionizing radiation and temperature regime of storage can slow down the rate of microorganisms multiplication in the product and increase its shelf life.

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