Effects of radiation pasteurization on Salmonella. III. Radiation lethality and the frequency of mutation to antibiotic resistance

Abstract

The radiation resistance (D, in megarads) of six strains of Salmonella irradiated at 4C in brain heart infusion suspension ranged from 0.042 for S. enteritidis to 0.084 for S. thompson. The resistance values were 0.048 for S. typhimurium, strain SR-11, 0.060 for S. typhimurium, strain RIA, and S. newport, and 0.078 for S. heidelberg. The mutation frequency to tetracycline resistance of S. typhimurium, strain SR-11, increased between 0 and 0.05 Mrad and declined thereafter with increasing radiation dose. After 0.5-Mrad exposure, the mutation frequency was essentially the same as in control populations. The mutation frequency to streptomycin resistance of S. typhimurium, strain SR-11, decreased at doses greater than 0.05 Mrad and increased only slightly for the more radiation-resistant serotypes, S. typhimurium, strain RIA, S. thompson, and S. heidelberg. The average mutation frequency of the four Salmonella cultures tested was essentially unchanged (less than 1 log difference) between 0.05 and 0.5 Mrad, while the difference in reduction in viable numbers was 5 logs or greater. The evidence presented indicates that with the proper choice of processing parameters, the application of radiation pasteurization could drastically reduce the possibility of transmission of Salmonella by poultry and thereby decrease the public health hazards associated with this microorganism.

Oxidative Stress Resistance inDeinococcus radiodurans

“…In other bacteria, one or more doses of radiation can cause an increase in radiation resistance (132,358,481), an increase in antibiotic resistance (498), morphological changes (173,358), biochemical changes (173), and decreased pathogenicity (180,498). Irradiated or chemically treated D. radiodurans cells usually give rise to colonies identical to those of unirradiated bacteria, although some colonies are smaller, pigmentless, and rough with irregular edges (161,434).…”

Wholesomeness of Irradiated Foods: A Review

“…(2) Three Indian studies showed abnormal white blood cells in children and monkeys and rats fed irradiated wheat (Baskaram and Sadasivan 1975;andVijayalaxmi 1975 and. (3) Two Indian studies showed that irradiated wheat, maize, sorghum, pearl millet, potatoes, and onions produced more aflatoxins than the non-irradiated samples Tulepule 1976 and.…”

“…No chromosomal effects from consumption of irradiated poultry meat could be discerned. (Tracor Jitco, Inc. 1983) In the aflatoxin studies by Tulepule (1976 and the samples were heat sterilized before infection with fungi. Such a heat sterilization process, like many other food processes, destroys natural antifungal conponents in the food (Sharma et aZ1981).…”

“…This is an important subject. Many very able microbiologists have been concerned and have researched it for many years (Among others: Erdman et al 1961;Thatcher 1963;Christensen and Kjems 1965;Licciardello et al 1969;Epps and Idziak 1970;Previtte et al 1970;Cliver 1977;Maxcy 1977).…”

“…The irradiation process is no exception. The mutants produced or selected by the irradiation method have usually been less competitive than the unmutated natural flora (Previtte et al 1970;Cliver 1977;Maxcy 1977). Radiation usually destroys the genes rather than creates them.…”