[The inactivation of mycoplasmas and bacteria in calf serum by 60Co gamma rays]

Reported in this paper is the use of 60Co gamma radiation to inactivate mycoplasmas in calf serum, newborn calf serum, and fetal calf serum. A dose of 3 kGy, independent of dose rate, was found to be sufficient for inactivation in the above sera of several mycoplasmas, including Acholeplasma laidlawii, Mycoplasma (M.) orale, M. arginini, M. hyorhinis, and M. bovis. The critical dose proved to be at 2 kGy. No difference was found to exist between the above species in susceptibility to irradiation in diluted sera (50%) and 10% in Eagle MEM). Sensibility of wild mycoplasma strains was found to be identical with that of laboratory strains. Hence, 60Co gamma irradiation of sera appears to be a safe method by which to make sera mycoplasma-free. Bacillus subtilis in calf serum was inactivated by doses above 18 kGy, with the critical dose being 15 kGy.