| Abstract |
Physical sterilization methods using ultraviolet radiation and
ionizing radiation such as gamma ray and electron beam are
applied in various industry fields due to disinfection effects and
economic efficiency but may also cause microbial mutation. In
this research, Salmonella enterica and Escherichia coli strains
were treated with ionizing and ultraviolet radiation and their
survival rate, mutation rate, and DNA damage were studied to
evaluate the genetic safety. The survival rate of the strains
decreased drastically as the irradiation dose of ultraviolet ray,
gamma ray, and electron beam increased, and over 90% of the
strain was exterminated at a dosage of 0.40~25.06 mJ/cm
3
,
0.11~0.22 kGy, 0.14~0.53 kGy respectively. In SOS / umu-test,
genotoxicity causing DNA damage was identified in all samples.
In Ames test, back-mutation rate increased to 3.82 × 10
-4
and
9.84 × 10
-6
respectively when exposed to ultraviolet ray and
gamma ray. At exposure to ultraviolet ray, gamma ray, and
electron beam with dosage of over 99.99% extinction rate of S.
enterica TA100, back-mutation rate increased 347 times, 220
times, 0.6 times respectively to the spontaneous back-mutation
rate. Rifampicin resistance mutation rate of E. coli CSH100
exposed to ultraviolet ray, gamma ray, and electron beam was
2.46 × 10
-6
, 1.66 × 10
-6
, 4.12 × 10
-7
respectively. Therefore, gamma
radiation is effective in microorganism control from the perspective
of disinfection and electron beam has the advantage
of sterilizing with little DNA damage and bacterial mutation. |
