Chemical States of Bacterial Spores: Dry-Heat Resistance

Alderton, Gordon; Snell, Neva

doi:10.1128/aem.17.5.745-749.1969

Cited by 22 publications

(25 citation statements)

References 3 publications

(5 reference statements)

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“…A number of other plating media have been commonly used in inactivation studies of B. sfearofhermophilus. These include dextrose tryptone agar with or without starch (Alderton & Snell 1969;Evancho et al 1974;Maunder 1976;Wallace et al 1978) and Trypticase soy agar (Gauthier et al 1978). When these three media were tested the number of survivors, 0.027%, was highest on dextrose tryptone agar plus starch, still considerably less than recovery on TPDP plus starch or charcoal.…”

Section: Resultsmentioning

confidence: 99%

Recovery of Spores of Bacillus stearothermophilus from Thermal Injury

Labbé

1979

Journal of Applied Bacteriology

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Bacillus stearothermophilus grown in nutrient broth produced a product which promoted recovery from thermal injury of its spores. This phenomenon was observed with nutrient agar as the plating medium but not with a medium composed of Trypticase, Phytone, dextrose and phosphate (TPDP). Recovery of injured spores was greatest in such a medium if it contained starch or charcoal. Trypticase soy agar and dextrose tryptone agar were markedly inferior to TPDP medium.

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Section: Resultsmentioning

confidence: 99%

Recovery of Spores of Bacillus stearothermophilus from Thermal Injury

Labbé

1979

Journal of Applied Bacteriology

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“…In addition to wet heat, spores are also significantly (c. 30°C) more resistant to dry heat than are the corresponding growing cells . Spores of thermophiles are no more dry heat resistant than are spores of mesophiles (Alderton and Snell 1969), but most factors potentially responsible for spore resistance to dry heat have not been investigated thoroughly, including DPA, core mineral content and sporulation temperature. However, the a/b-type SASP play a major role in the dry heat resistance of B. subtilis spores, as a ) b ) spores are as sensitive to dry heat as dry growing cells.…”

Section: Dry Heatmentioning

confidence: 99%

Spores of Bacillus subtilis: their resistance to and killing by radiation, heat and chemicals

2006

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A number of mechanisms are responsible for the resistance of spores of Bacillus species to heat, radiation and chemicals and for spore killing by these agents. Spore resistance to wet heat is determined largely by the water content of spore core, which is much lower than that in the growing cell protoplast. A lower core water content generally gives more wet heat-resistant spores. The level and type of spore core mineral ions and the intrinsic stability of total spore proteins also play a role in spore wet heat resistance, and the saturation of spore DNA with a/b-type small, acid-soluble spore proteins (SASP) protects DNA against wet heat damage. However, how wet heat kills spores is not clear, although it is not through DNA damage. The a/b-type SASP are also important in spore resistance to dry heat, as is DNA repair in spore outgrowth, as Bacillus subtilis spores are killed by dry heat via DNA damage. Both UV and c-radiation also kill spores via DNA damage. The mechanism of spore resistance to c-radiation is not well understood, although the a/b-type SASP are not involved. In contrast, spore UV resistance is due largely to an alteration in spore DNA photochemistry caused by the binding of a/b-type SASP to the DNA, and to a lesser extent to the photosensitizing action of the spore core's large pool of dipicolinic acid. UV irradiation of spores at 254 nm does not generate the cyclobutane dimers (CPDs) and (6-4)-photoproducts (64PPs) formed between adjacent pyrimidines in growing cells, but rather a thymidylthymidine adduct termed spore photoproduct (SP). While SP is formed in spores with approximately the same quantum efficiency as that for generation of CPDs and 64PPs in growing cells, SP is repaired rapidly and efficiently in spore outgrowth by a number of repair systems, at least one of which is specific for SP. Some chemicals (e.g. nitrous acid, formaldehyde) again kill spores by DNA damage, while others, in particular oxidizing agents, appear to damage the spore's inner membrane so that this membrane ruptures upon spore germination and outgrowth. There are also other agents such as glutaraldehyde for which the mechanism of spore killing is unclear. Factors important in spore chemical resistance vary with the chemical, but include: (i) the spore coat proteins that likely react with and detoxify chemical agents; (ii) the relative impermeability of the spore's inner membrane that restricts access of exogenous chemicals to the spore core; (iii) the protection of spore DNA by its saturation with a/b-type SASP; and (iv) DNA repair for agents that kill spores via DNA damage.Given the importance of the killing of spores of Bacillus species in the food and medical products industry, a deeper understanding of the mechanisms of spore resistance and killing may lead to improved methods for spore destruction.

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“…Spores thus exhibit a base exchange behaviour which reduces, restores or enhances the heat resistance of fully formed spores.There are few reports in the literature on the effects of antimicrobial agents on such spore forms, although it has recently been noted that hydrogen (H)-form spores of Bacillus subtilis var. niger were considerably more sensitive than normal or calcium (Ca)-form spores to propylene oxide (Tawaratani & Shibasaki, 1973).Glutaraldehyde, an important disinfectant and chemosterilizer (Borick, 1968 ; Russell, 1971), is markedly dependent for its activity on environmental pH, the optimum pH being c. 8-83. It therefore seemed of interest to study the effect of glutaraldehyde on the viability of different forms of the same spores (B. pumilus).…”

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Sensitivity and Resistance to Glutaraldehyde of the Hydrogen and Calcium Forms of Bacillus pumilus spores

Thomas

Russell

1975

Journal of Applied Bacteriology

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BACTERIAL SPORES appear to be more readily inactivated at low than at high pH values. This is considered to be due to the influence of the type of ions that would adsorb on the spore surface (Alderton & Snell, 1969, 1970. Spores thus exhibit a base exchange behaviour which reduces, restores or enhances the heat resistance of fully formed spores.There are few reports in the literature on the effects of antimicrobial agents on such spore forms, although it has recently been noted that hydrogen (H)-form spores of Bacillus subtilis var. niger were considerably more sensitive than normal or calcium (Ca)-form spores to propylene oxide (Tawaratani & Shibasaki, 1973).Glutaraldehyde, an important disinfectant and chemosterilizer (Borick, 1968 ; Russell, 1971), is markedly dependent for its activity on environmental pH, the optimum pH being c. 8-83. It therefore seemed of interest to study the effect of glutaraldehyde on the viability of different forms of the same spores (B. pumilus). Methods Organ ismThis was B. pumilus E. 601. Spores of B. pumilus E. 601 were produced as described by Thomas & Russell (1974a, b). Production of H-form and Ca-form sporesH-form spores were produced by suspending normal spores in nutrient broth (Oxoid, Ltd, London, England) adjusted to pH 1.2 and incubating at 20" overnight. These were centrifuged, washed and resuspended in sterile water. Ca-forms of H-spores were obtained by centrifuging the H-spores and resuspending them in 0.02 M-calcium acetate, pH 9.7, overnight at 20". Thermal sensitivityThe thermal sensitivity of normal, H-form and Ca-form spores was determined by suspending them in sterile glass distilled water and heating at 77" for 60 min. Samples were removed at intervals, serially diluted in sterile water and plated in nutrient agar.

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Chemical States of Bacterial Spores: Dry-Heat Resistance

Cited by 22 publications

References 3 publications

Recovery of Spores of Bacillus stearothermophilus from Thermal Injury

Recovery of Spores of Bacillus stearothermophilus from Thermal Injury

Spores of Bacillus subtilis: their resistance to and killing by radiation, heat and chemicals

Sensitivity and Resistance to Glutaraldehyde of the Hydrogen and Calcium Forms of Bacillus pumilus spores

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