Abstract
The effect of ultrasonic irradiation and gamma-ray radiation on the inactivation of microorganisms is strongly associated with free radicals which generated from water molecule. In this aspect, it is considered that the both effects are seemed to be similar in terms of the radical contribution, especially at a range around 200 kHz for sonication condition. However, in case of ultrasound, the shock wave also contributes for microbial disruption of cell components including cell membrane or genic compound, which is lead to cell death. In this study, we compared the effect of ultrasound and gamma-ray considering the indication of cell membrane permeability and nucleic acid. After each sonication and gamma radiation, the amount of nucleic acid was measured by using BACTANA[○!R] (an automatic microbial analyzer based on flow cytometry) in addition to colony counting. It is observed that the nucleic acid synthesis significantly increased within the cells before entering the logarithmic phase of their growth. Moreover, it was found that the pattern of increasing amount of nucleic acid following with the growth of the cells was different between sonication and gamma-ray radiation. In case of sonication, increasing rate hardly change depending on the sonication time. On the other hand, it was decreased with increasing intensity of gamma-ray radiation. It seems that the damage on survival cell remain after gamma-ray radiation and it takes long time to repair and growth of the cell.
