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Summary. Increasing concentrations (2, 4 and 8% w/v) of NaCl in the heating medium reduced the heat resistance of spores of Bacillus stearothermophilus but had no effect on the heat or radiation resistances of B. pumilus, B. subtilis and B. subtilis var. niger or on the radiation resistance of B. stearothermophilus. Increasing heat damage rendered all the spores increasingly sensitive to NaCl in the recovery medium. The presence of NaCl during heating reduced the subsequent NaCl sensitivity of B. pumilus, B. subtilis and B. subtilis var. niger but increased that of B. stearothermophilus. Increasing doses of γ radiation rendered the spores of B. stearothermophilus increasingly sensitive to NaCl in the recovery medium. The effect was less pronounced with B. pumilus, whilst B. subtilis and B. subtilis var. niger showed little change in their post‐irradiation sensitivity to NaCl. The presence of NaCl during γ irradiation had no effect on the subsequent pattern of postirradiation NaCl sensitivity.

No abstract

Summary. Moist heat at 82° (100° for Bacillus stearothermophilus) and solutions of 0.2% w/v chlorocresol or 0.01% w/v benzalkonium chloride at 24° separately showed no sporicidal activity against B. pumilis, B. stearothermophilus, B. subtilis and B. subtilis var. niger. Spores of the last organism were the most sensitive to γ radiation, the D value being 0.16 Mrad. Prior irradiation with a dose of 0.16 Mrad brought about only a slight increase in the sensitivity of the spores to moist heat. The presence of bactericide during irradiation did not affect radiation resistance. Inactivation rates were greater when the spores were heated in the presence of a bactericide than in aqueous suspension and benzalkonium chloride was more active than chlorocresol. Chlorocresol enhanced the heat activation of B. stearothermophilus at 100°. Irradiation in the presence of 0.2% w/v chlorocresol or 0.01% w/v benzalkonium chloride had no effect on the subsequent resistance of the spores when heated in the presence of these bactericides. It is concluded that it is unlikely that combinations of moist heat, radiation and bactericides, each less severe than when used in an accepted sterilization process, will lead to an alternative process which, while less damaging to the materials being sterilized, would still maintain the accepted standards of freedom from contamination.

2‐, 3‐, oder 4‐Acetylpyridinsemicarbazon (II) wird mit SeO2 zu den Pyridylselen‐adiazolen (I) umgesetzt.