Studies on a Radio-resistant Coccus Isolated from Bombay Duck (Harpodon nehereus)

SUMMARY: An extremely radio-resistant orange-red pigmented Micrococcus sp. was isolated from irradiated Bombay duck (Harpodon nehereus). The organism was a Gram-positive vegetative tetracoccus, catalase-positive, sensitive to heat and nonpathogenic. It differed from M. radiodurans by being smaller in size, salt-tolerant, hydrolysing gelatin very slowly, and much more resistant to gamma radiation. The radiation survival curve of the new coccus was sigmoidal, punctuated with a very large shoulder extending beyond 1.5 Mrad.