Article

Effect of combined heat and radiation on microbial destruction.

Applied and Environmental Microbiology (Impact Factor: 3.95). 06/1977; 33(5):1170-6.
Source: PubMed

ABSTRACT A series of experiments at several levels of relative humidity and radiation dose rates was carried out using spores of Bacillus subtilis var. niger to evaluate the effect of heat alone, radiation alone, and a combination of heat and radiation. Combined heat and radiation treatment of microorganisms yields a destruction rate greater than the additive rates of the independence agents. The synergistic mechanism shows a proportional dependency on radiation dose rate an Arrhenius dependency on temperature, and a dependency on relative humidity. Maximum synergism occurs under conditions where heat and radiation individually destroy microorganisms at approximately equal rates. Larger synergistic advantage is possible at low relative humidities rather than at high relative humidities.

0 Bookmarks
 · 
205 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Microbial pathogens in municipal sewage sludges need to be inactivated prior to environmental disposal. The efficacy of high energy (10MeV) e-beam irradiation to inactivate a variety of selected microbial pathogens and indicator organisms in aerobically and anaerobically digested sewage sludge was evaluated. Both bacterial and viral pathogens and indicator organisms are susceptible to e-beam irradiation. However, as expected there was a significant difference in their respective e-beam irradiation sensitivity. Somatic coliphages, bacterial endospores and enteric viruses were more resistant compared to bacterial pathogens. The current US EPA mandated 10kGy minimum dose was capable of achieving significant reduction of both bacterial and viral pathogens. Somatic coliphages can be used as a microbial indicator for monitoring e-beam processes in terms of pathogen inactivation in sewage sludges.
    Bioresource Technology 07/2013; · 5.04 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Effective control of spore-forming bacilli begs suitable physical or chemical methods. While many spore inactivation techniques have been proven effective, electron beam (EB) irradiation has been frequently chosen to eradicate Bacillus spores. Despite its widespread use, there are limited data evaluating the effects of EB irradiation on Bacillus spores. To study this, B. atrophaeus spores were purified, suspended in sterile, distilled water, and irradiated with EB (up to 20 kGy). Irradiated spores were found (1) to contain structural damage as observed by electron microscopy, (2) to have spilled cytoplasmic contents as measured by spectroscopy, (3) to have reduced membrane integrity as determined by fluorescence cytometry, and (4) to have fragmented genomic DNA as measured by gel electrophoresis, all in a dose-dependent manner. Additionally, cytometry data reveal decreased spore size, increased surface alterations, and increased uptake of propidium iodide, with increasing EB dose, suggesting spore coat alterations with membrane damage, prior to loss of spore viability. The present study suggests that EB irradiation of spores in water results in substantial structural damage of the spore coat and inner membrane, and that, along with DNA fragmentation, results in dose-dependent spore inactivation.
    International Journal of Microbiology 01/2012; 2012:579593.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The threat of bioterrorism has prompted a reaction from governments and scientists in a rapidly expanding war against unknown attackers. In the United States, the Postal Service has announced new safety measures that include processing mail with electron beam technology to eliminate potentially dangerous microorganisms. The microbiocidal activity of radiation is one of the radiobiological effects that is of considerable interest in medicine and public health. It has already been employed for sterilizing medical equipment and supplies, medicaments, pharmaceuticals, cosmetics and biological tissue. L. G. Gazso recommended first to use ionizing radiation for the inactivation of biological weapon agents (VI. Int. Symposium on Protection Against Chemical and Biological Warfare Agents, Stockholm, 1998. and Symposium on Nuclear, Biological and Chemical Treats in the 21st Century, Helsinki, 2000.) The calculation of inactivation dose depends on three parameters, namely the initial microbiological contamination (number of microbes), the radiosensitivity of microorganism and the assurance of sterility required. The radiosensitivity of microorganism towards high energy radiation varies widely: different types, species and strains exhibit greatly different radiation sensitivity. Certain environmental factors are also able to influence the actual radiation response. The intent of this paper is to provide a broad overview of the importance of radiation neutralizing of bio-warfare/bioterrorism agents, indicate what further work is needed and summarize the recent experiences. The application of radiation technology for inactivation of bioterrorism agents and the main results of NATO Advanced Research Workshop on Radiation Inactivation of Bioterrorism Agents (7-9 March, 2004, Budapest, Hungary, NATO Co-director L. G. Gazso) are described in this paper.
    10/2004;

Full-text

View
1 Download
Available from