Sensitivities to Hydrogen Peroxide Vapor of Intact and Decoated Spores of Bacillus subtilis As Influenced by Divalent Cations Supplemented in Sporulation Medium.

Abstract

We developed Mn-supplemented, Fe-supplemented , and Ca-supplemented spores of Bacillus subtilis 168 and ATCC9372 in the respective presence of manganese , ferric and calcium ions, and compared their resistance to vapor-phase hydrogen peroxide with that to aqueous phase hydrogen peroxide and heat. Mn-supplemented spores were the most sensitive to heat and hydrogen peroxide solution but was the most resistant to vapor-phase hydrogen peroxide at low relative humidities as compared with Fe-supplemented and Ca-supplemented spores of the two strains. In the vapor-phase hydrogen peroxide treatment , the spore resistance was affected by the relative humidity during the period for spore preparation and was lowest at a relative humidity of 33%. The removal of the spore coat from the spores of strain 168 markedly sensitized Fe-supplemented and Ca-supplemented spores , and also slightly sensitized Mnsupplemented spores, to vapor-phase hydrogen peroxide. These results indicate that both divalent cations in spores and the relative humidity affect the spore resistance to hydrogen peroxide vapor and suggest that the spore coat plays a role in this resistance.

Modelling the combined effects of pH, temperature and sodium chloride stresses on the thermal inactivation of Bacillus subtilis spores in a buffer system*

“…Spores were harvested (when 90% of the cells had sporulated) by centrifugation at 7000 × g for 20 min at 4°C. The resultant spores were treated with lysozyme (1 mg ml −1 , Sigma Chemical Co., St Louis, MO, USA) and washed with 50 mmol l −1 potassium phosphate buffer at pH 7·0 as described previously (Tsuchida and Tsuchido 1997). The spores suspended in sterile distilled water were frozen and stored at −84°C until use.…”

“…A previous work studied the heat resistance of B. subtilis spores in different oils (Nakagawa et al. 1998) and also the effects of hydrogen peroxide and divalent cations in the sporulation medium (Tsuchida and Tsuchido 1997). Such data generated in oil and buffer systems are important in the construction of thermal inactivation databases mimicking the actual food systems.…”

Supercritical carbon dioxide and hydrogen peroxide cause mild changes in spore structures associated with high killing rate of Bacillus anthracis

“…Furthermore, it may not be possible to extrapolate previous studies of aqueous H 2 O 2 sterilization to what occurs on spore deactivation with H 2 O 2 in an SCCO 2 phase. Decades of study on H 2 O 2 sterilization have revealed that the damage to the spores depends on concentration and whether H 2 O 2 is in the liquid or vapor state (King and Gould, 1969, Shin et al, 1994, Tsuchida and Tsuchido, 1997.…”

Inactivation of Neosartorya fischeri and Paecilomyces variotii on paperboard packaging material by hydrogen peroxide and heat

“…Hydrogen peroxide solutions were prepared by mixing food grade concentrated hydrogen peroxide (50% w/w) (Peróxidos do Brasil Ltda, Curitiba, Brazil) with sterile deionized water and used on the same day (Tsuchida & Tshuchido, 1997). The concentration of the diluted solutions was checked before their use as proposed by Buchen and Marth (1977).…”