Release of Cellular Constituents During Heat Inactivation of Endospores of Aerobic Bacilli

Walker, H. W.; Matches, Jack R.

doi:10.1111/j.1365-2621.1965.tb01882.x

Cited by 13 publications

(10 citation statements)

References 18 publications

(19 reference statements)

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“…These results are in complete agreement with the data obtained from the experiment on the effect of pH. Most heat-resistant spores release the least DPA under equal conditions (Walker et al, 1965). Spores of the rough variant were found more heat resistant (Rotman, 1967).…”

Section: Effect Of Heating Timesupporting

confidence: 91%

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The Release of Dipicolinic Acid from Spores of Bacillus stearothermophilus NCA 1518

Rotman

Fields

1969

Journal of Food Science

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Both pH of the spore suspensions and autoclaving time affect the release of dipicolinic acid (DPA) from spores. At pH 14 maximum release of DPA was obtained for spore suspensions of both variants autoclaved at 250°F for 15 min. With the smooth variant. maximum release of DPA was achieved at DH 7.0. Autoclavina at 250°F for 15 and 7d min was required for complete release of DPA from spores o'i the smooth and the rough variants. Loss of viability of spores of both variants succeeded complete release of DPA.

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Section: Effect Of Heating Timesupporting

confidence: 91%

“…1). Walker et al (1965) reported that endospores of aerobic bacilli release the least DPA at pH 7.0, with more acid being released under unfavorable conditions. Similar results were observed in this study.…”

Section: Effect Of Phmentioning

confidence: 99%

The Release of Dipicolinic Acid from Spores of Bacillus stearothermophilus NCA 1518

Rotman

Fields

1969

Journal of Food Science

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“…Third, DPA is released during wet-heat-induced spore inactivation, which is the focus of this study. The relationship between the release of DPA and the heat resistance of spores has been studied for spores from a number of Bacillus species, all showing that DPA release is slower than the loss of viability of the spores during heating (13,47). Although the correlation between DPA release and the spore death rate was complex, in these studies higher rates of death were associated with higher rates of DPA release.…”

mentioning

confidence: 92%

Assessment of Heat Resistance of Bacterial Spores from Food Product Isolates by Fluorescence Monitoring of Dipicolinic Acid Release

Kort

O'Brien

Stokkum

et al. 2005

Appl Environ Microbiol

133

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This study is aimed at the development and application of a convenient and rapid optical assay to monitor the wet-heat resistance of bacterial endospores occurring in food samples. We tested the feasibility of measuring the release of the abundant spore component dipicolinic acid (DPA) as a probe for heat inactivation. Spores were isolated from the laboratory type strain Bacillus subtilis 168 and from two food product isolates, Bacillus subtilis A163 and Bacillus sporothermodurans IC4. Spores from the lab strain appeared much less heat resistant than those from the two food product isolates. The decimal reduction times (D values) for spores from strains 168, A163, and IC4 recovered on Trypticase soy agar were 1.4, 0.7, and 0.3 min at 105°C, 120°C, and 131°C, respectively. The estimated Z values were 6.3°C, 6.1°C, and 9.7°C, respectively. The extent of DPA release from the three spore crops was monitored as a function of incubation time and temperature. DPA concentrations were determined by measuring the emission at 545 nm of the fluorescent terbium-DPA complex in a microtiter plate fluorometer. We defined spore heat resistance as the critical DPA release temperature (T c ), the temperature at which half the DPA content has been released within a fixed incubation time. We found T c values for spores from Bacillus strains 168, A163, and IC4 of 108°C, 121°C, and 131°C, respectively. On the basis of these observations, we developed a quantitative model that describes the time and temperature dependence of the experimentally determined extent of DPA release and spore inactivation. The model predicts a DPA release rate profile for each inactivated spore. In addition, it uncovers remarkable differences in the values for the temperature dependence parameters for the rate of spore inactivation, DPA release duration, and DPA release delay.Bacterial spores are common contaminants of food products, and their outgrowth may cause food spoilage or foodborne illness. They are extremely resistant to heat and other preservation treatments in comparison to vegetative cells. The inactivation of spores requires high temperatures and long heating times, which are costly and detrimental to the nutritional and organoleptic quality of most food products. To minimize the required heat treatment, there is an urgent need in the food industry for tailored preservation procedures, based on models that accurately predict the presence of viable cells at every step of the food production process (6, 41). To assess the required heat inactivation procedure for the most resistant cell type, the bacterial spore, we isolated and classified two food contaminants and developed a rapid and sensitive screening method to determine the heat resistance of their spores.Under nutrient-limited conditions, vegetative cells of Bacillus species undergo the cell differentiation process of sporulation (17, 42). The resulting spores are metabolically dormant and show, besides resistance to heat, resistance to other potentially lethal treatments that include radiati...

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“…The same conclusion was reached in all these studies: that release of Dpa proceeds at a slower rate than loss of viability of spores during heating, suggesting that death precedes the release of Dpa. Walker & Matches (1965) suggested that the release of Dpa is a secondary reaction reflecting a change in cellular organisation which was primarily responsible for the inactivation of the spore.…”

mentioning

confidence: 99%

The release of dipicolinic acid during heating and its relation to the heat destruction of Bacillus stearothermophilus spores

1985

Journal of Applied Bacteriology

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The rates of dipicolinic acid (Dpa) release and the rates of death were studied for spores of five strains of Bacillus stearothermophilus. It was observed that a highly significant relationship exists between the rate of Dpa release and rate of spore death for the four out of five strains tested and for all test temperatures. At 115 degrees C the rate of Dpa release was found to be faster than the rate of death, equal at 120 degrees C and slower at 125 degrees C. The role of Dpa in heat resistance was considered and a theory is proposed to explain the mechanism by which the heat resistance of bacterial spores is overcome.

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Release of Cellular Constituents During Heat Inactivation of Endospores of Aerobic Bacilli

Cited by 13 publications

References 18 publications

The Release of Dipicolinic Acid from Spores of Bacillus stearothermophilus NCA 1518

The Release of Dipicolinic Acid from Spores of Bacillus stearothermophilus NCA 1518

Assessment of Heat Resistance of Bacterial Spores from Food Product Isolates by Fluorescence Monitoring of Dipicolinic Acid Release

The release of dipicolinic acid during heating and its relation to the heat destruction of Bacillus stearothermophilus spores

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