Irradiation sensitivity of five Salmonella enteritidis isolates inoculated either on the surface or inside of whole shell eggs were determined. The shell eggs were irradiated at doses of 0, 0.5, 1.0, and 1.5 kGy. A minimal dose of 0.5 kGy was sufficient to eliminate all the isolates from the surface of whole eggs; however, the same isolates were more resistant to irradiation when present inside the eggs. The ATCC 13076 isolate was significantly more sensitive to irradiation, with a D value of 0.32 kGy, than the other four isolates from animal origin. Irradiation D values of the latter ranged from 0.39 to 0.41 kGy. Liquid whole eggs were also inoculated (2.4 x 10(6) cells per milliliter) with two S. enteritidis isolates and were heat-treated at 50 C for 0, 20, 40, or 60 min followed by irradiation at 0, 0.25, 0.5, 0.75, or 1.0 kGy. The results indicate that mild heating prior to irradiation was ineffective in reducing the irradiation D values. However, on the basis of the D values obtained, an irradiation dose of 1.5 kGy should be sufficient to reduce Salmonella counts by approximately 4 log10 in both whole shell and liquid eggs. Results also indicate that color and thermal characteristics of the whole or liquid eggs were unaffected by a 1.5-kGy dose of irradiation.
The yeastlike form of Paracoccidioides brasiliensis strain IVIC Pb9 reduced the amount of a-1,3-glucan in its cell wall from 45 to 3% when subcultured in vitro for several years. This strain regained its a-1,3-glucan up to 25% of the total cell wall when grown in vivo. A mutant strain of P. brasiliensis Pb9, named IVIC Pbl4O, reported to have 1,3-mannan instead of a-glucan in the cell wall, could not be recovered from experimentally infected animals. The existence of some relationship between the presence of a-1,3-glucan in the cell wall of the yeastlike form and the pathogenicity of this fungus is suggested in this report.
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