Inactivation of histidine decarboxylase by gamma irradiation for controlling histamine formation

In this study, the effects of gamma irradiation on the survival of Morganella morganii and Photobacterium phosphoreum and the activity of their crude histidine decarboxylase (HDC) were investigated. The two strains and their crude HDC were irradiated up to 10 kGy. Viable cells of M. morganii and P. phosphoreum were not detected at any dose. The activity of crude HDC was decreased with increasing dose. In particular, the gamma irradiation at 5 and 10 kGy resulted in > 90% inactivation of crude HDC from M. morganii and P. phosphoreum, respectively. In SDS-PAGE and native PAGE, slight structural changes of crude HDC appeared with gamma irradiation. These results suggest that gamma irradiation is effective in reducing histamine production through inactivation survival of M. morganii and P. phosphoreum, and their histidine decarboxylase activity.