Thermo-structural studies of spores subjected to high temperature gas environments

Kumar, Rakesh; Saurav, Samarth; Титов, Е. В.; Levin, Deborah A.; Long, Robert; Neely, W. C.; Setlow, Peter

doi:10.1016/j.ijheatmasstransfer.2010.11.004

Cited by 13 publications

(3 citation statements)

References 19 publications

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“…An initial modelling of the response of hydrated spores upon exposure to a HTGE had suggested that spores might rupture due to rapid volatilization of water in the spore core (Kumar et al . ). Consequently, analysis of the mechanism of HTGE killing of B. anthracis spores was begun by using a number of microscopy techniques to examine both control spores as well as spores killed 95–99% by HTGE treatment.…”

Section: Resultsmentioning

confidence: 97%

“…Spores of Bacillus species can be killed by a number of mechanisms, including damage to: (i) DNA; (ii) one or more crucial core proteins; (iii) one or more constituents, most likely proteins, in the inner membrane; (iv) a spore protein(s) essential for spore germination; and (v) the permeability barriers that restrict loss of small molecules from the spore core, with this perhaps leading to spore rupture (Setlow et al 2002;Setlow 2006). An initial modelling of the response of hydrated spores upon exposure to a HTGE had suggested that spores might rupture due to rapid volatilization of water in the spore core (Kumar et al 2011). Consequently, analysis of the mechanism of HTGE killing of B. anthracis spores was begun by using a number of microscopy techniques to examine both control spores as well as spores killed 95-99% by HTGE treatment.…”

Section: Microscopic Analysis Of Htge-treated and Untreated Sporesmentioning

confidence: 99%

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Mechanism of killing of spores of Bacillus anthracis in a high-temperature gas environment, and analysis of DNA damage generated by various decontamination treatments of spores of Bacillus anthracis ,Bacillus subtilis and Bacillus thuringiensis

et al. 2014

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Aims: To determine how hydrated Bacillus anthracis spores are killed in a high-temperature gas environment (HTGE), and how spores of several Bacillus species including B. anthracis are killed by UV radiation, dry heat, wet heat and desiccation. Methods and Results: Hydrated B. anthracis spores were HTGE treated at c. 220°C for 50 ms, and the treated spores were tested for germination, mutagenesis, rupture and loss of dipicolinic acid. Spores of this and other Bacillus species were also examined for mutagenesis by UV, wet and dry heat and desiccation. There was no rupture of HTGE-treated B. anthracis spores killed 90-99Á9%, no mutagenesis, and release of DPA and loss of germination were much slower than spore killing. However, killing of spores of B. anthracis, Bacillus thuringiensis and Bacillus subtilis by UV radiation or dry heat, but not wet heat in water or ethanol, was accompanied by mutagenesis.Conclusions: It appears likely that HTGE treatment kills B. anthracis spores by damage to spore core proteins. In addition, various killing regimens inactivate spores of a number of Bacillus species by the same mechanisms. Significance and Impact of the Study: This work indicates how hydrated spores treated in a HTGE such as might be used to destroy biological warfare agent stocks are killed. The work also indicates that mechanisms whereby different agents kill spores are similar with spores of different Bacillus species.

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Section: Resultsmentioning

confidence: 97%

Section: Microscopic Analysis Of Htge-treated and Untreated Sporesmentioning

confidence: 99%

Mechanism of killing of spores of Bacillus anthracis in a high-temperature gas environment, and analysis of DNA damage generated by various decontamination treatments of spores of Bacillus anthracis ,Bacillus subtilis and Bacillus thuringiensis

et al. 2014

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“…According to previous modeling studies (36,57), heat transfer within a spore is very rapid: it requires less than 1 ms (for well-dispersed, isolated spores) to 21 ms (for spores in a 1,000-spore cluster) for a spore to reach the steady-state temperature. As the spore core temperature rises rapidly, its water content (both chemically bonded and mobile water molecules) starts to vaporize and expand.…”

Section: Discussionmentioning

confidence: 99%

Nanoscale Structural and Mechanical Analysis of Bacillus anthracis Spores Inactivated with Rapid Dry Heating

Xing

Felker

et al. 2014

Appl Environ Microbiol

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Effective killing of Bacillus anthracis spores is of paramount importance to antibioterrorism, food safety, environmental protection, and the medical device industry. Thus, a deeper understanding of the mechanisms of spore resistance and inactivation is highly desired for developing new strategies or improving the known methods for spore destruction. Previous studies have shown that spore inactivation mechanisms differ considerably depending upon the killing agents, such as heat (wet heat, dry heat), UV, ionizing radiation, and chemicals. It is believed that wet heat kills spores by inactivating critical enzymes, while dry heat kills spores by damaging their DNA. Many studies have focused on the biochemical aspects of spore inactivation by dry heat; few have investigated structural damages and changes in spore mechanical properties. In this study, we have inactivated Bacillus anthracis spores with rapid dry heating and performed nanoscale topographical and mechanical analysis of inactivated spores using atomic force microscopy (AFM). Our results revealed significant changes in spore morphology and nanomechanical properties after heat inactivation. In addition, we also found that these changes were different under different heating conditions that produced similar inactivation probabilities (high temperature for short exposure time versus low temperature for long exposure time). We attributed the differences to the differential thermal and mechanical stresses in the spore. The buildup of internal thermal and mechanical stresses may become prominent only in ultrafast, high-temperature heat inactivation when the experimental timescale is too short for heat-generated vapor to efficiently escape from the spore. Our results thus provide direct, visual evidences of the importance of thermal stresses and heat and mass transfer to spore inactivation by very rapid dry heating. Bacterial spores are metabolically dormant cells formed in a process called sporulation, which is generally induced by reduced levels of nutrients in the environment (1-3). Efficient inactivation of spores is of critical importance for a wide range of applications, including biodefense, food safety, environmental protection, and medical device sterilization (4-6). Spores are known to be more resistant to inactivation by heating, radiation exposure, and chemical decontamination than their corresponding vegetative cells. While various methods, including heating, chemical treatment, radiation, and UV treatment, have been used to inactivate spores (4, 6, 7), thermal inactivation is often the method of choice for many applications (8). Thermal inactivation of Bacillus spores in laboratory studies is most often achieved by wet heat in which spores are fully hydrated during heating (9-11) or dry heat in which dry spores are heated on a solid substrate, in an ampoule heated by an oil bath, in a hot air plume, or by infrared heating (5,8,(12)(13)(14)(15)(16)(17)(18)(19)(20). It has long been observed that spores are much less resistant to heat in a well-hydr...

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On the neutralization of bacterial spores in post-detonation flows

2014

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Thermo-structural studies of spores subjected to high temperature gas environments

Cited by 13 publications

References 19 publications

Mechanism of killing of spores of Bacillus anthracis in a high-temperature gas environment, and analysis of DNA damage generated by various decontamination treatments of spores of Bacillus anthracis ,Bacillus subtilis and Bacillus thuringiensis

Mechanism of killing of spores of Bacillus anthracis in a high-temperature gas environment, and analysis of DNA damage generated by various decontamination treatments of spores of Bacillus anthracis ,Bacillus subtilis and Bacillus thuringiensis

Nanoscale Structural and Mechanical Analysis of Bacillus anthracis Spores Inactivated with Rapid Dry Heating

On the neutralization of bacterial spores in post-detonation flows

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