ArticleAuthors: Tran, Bang Diep; Nguyen, Thi Thom; Hoang, Dang Sang; Hoang, Phuong Thao; Nguyen, Van Binh; Ta, Bich Thuan; Vo, Thi Thuong Lan; Tran, Minh Quynh (2016)
The suspensions of Bacillus subtilis B5, a rather high protease production strain, in logarithmic growth phase were irradiated under gamma Cobalt-60 source at Hanoi Irradiation Center. After treatment, the irradiated cells were intermediately cultured in the nutrient agar plates supplemented without and with 20µg/ml streptomycin for screening. The radiation effects on their viability and mutant frequency were studied with radiation dose. The results showed that its survival rate was reduced with the dose as biphasic function. The cells irradiated at dose higher than 1200 Gy do not form colony in the medium containing streptomycin though they could survive in nutrient agar. Therefore... 
