The Korean Soclety of Plant Pathology : E ; Disease Management : E-7 ; Inactivation of Erwinia carotovora subsp. carotovora by gamma irradiation

Effective control of bacterial pathogens requires suitable physical or chemical methods. While many bacteria inactivation techniques have been proven to be effective, gamma irradiation (GI) has been frequently used to eradicate bacterial pathogens. Despite its widespread use, there is not much known about the inactivation mechanisms of bacteria by GI. To elucidate this, GI was evaluated for its in vitro and in vivo antibacterial ac-tivity against a postharvest bacterial pathogen, Erwinia carotovora supsb. carotovora on paprika. GI in E. carotovora supsb. carotovora cell suspension resulted in a dramatic reduction of the viable counts as well as an increase in the amounts of DNA and protein released from the cells. GI showed complete inactivation of E. carotovora supsb. carotovora, especially at a dose of 0.8 kGy. In addition, scanning electron microscopy of irradiated cells revealed severe damage on the surface of most bacterial cells. Along with the morphological changes of cells by GI, it also affected the mem-brane integrity in a dose-dependent manner. The mechanisms by which the GI decreased the bacterial soft rot of paprika can be directly associated with the disruption of the cell membrane of the bacterial pathogen. These findings suggest that GI has potential as an antibacterial approach to re-duce the severity of the soft rot of paprika.