Inactivation of Bacillus Endospores in Envelopes by Electron Beam Irradiation

Abstract

The anthrax incidents in the United States in the fall of 2001 led to the use of electron beam (EB) processing to sanitize the mail for the U.S. Postal Service. This method of sanitization has prompted the need to further investigate the effect of EB irradiation on the destruction of Bacillus endospores. In this study, endospores of an anthrax surrogate, B. atrophaeus, were destroyed to demonstrate the efficacy of EB treatment of such biohazard spores. EB exposures were performed to determine (i) the inactivation of varying B. atrophaeus spore concentrations, (ii) a D 10 value (dose required to reduce a population by 1 log 10 ) for the B. atrophaeus spores, (iii) the effects of spore survival at the bottom of a standardized paper envelope stack, and (iv) the maximum temperature received by spores. A maximum temperature of 49.2°C was reached at a lethal dose of ϳ40 kGy, which is a significantly lower temperature than that needed to kill spores by thermal effects alone. A D 10 value of 1.53 kGy was determined for the species. A surface EB dose between 25 and 32 kGy produced the appropriate killing dose of EB between 11 and 16 kGy required to inactivate 8 log 10 spores, when spore samples were placed at the bottom of a 5.5-cm stack of envelopes.

Research and Development of On-site Decontamination System for Biological and Chemical Warfare Agents

“…Bacteria, rickettsia and chlamydia can be decontaminated physically by elimination using the trapping filter. They can be sterilized biochemically by mutation of genomic and plasmid nucleic acids using high energy light irradiation, 55) by structural destruction through rapture of cell membranes or cell walls, by denaturation of host-recognizing molecules, or by inhibition of cell metabolism and proliferation, which lead to suppression of living, proliferating or infecting activity. Q fever is resistant to heat, drying and disinfectant solution, and stable in environment (−52-40 • C, dryness, 5-60 days).…”

Roles of the Major, Small, Acid-Soluble Spore Proteins and Spore-Specific and Universal DNA Repair Mechanisms in Resistance of Bacillus subtilis Spores to Ionizing Radiation from X Rays and High-Energy Charged-Particle Bombardment

“…On Earth, understanding extreme spore resistance to ionizing radiation is important in the areas of food preservation, medical sterilization, and decontamination from bioterror attack (4,17,47; reviewed in references 42 and 43). Off Earth, spore radiation resistance is important both in space flight and in ground-based simulations, in order to obtain information on the biological damage produced by exposure to space conditions (23,25,26,44).…”

Sterilization by Gamma Irradiation

“…For example, whilst sensitivity of spores from Bacillus megaterium was constant between -268 and -148°C, an increase in temperature to 20°C led to a 40% increase in sensitivity. Effect of temperature was observed to be similar for oxic and anoxic spores (Helfinstine et al, 2005).…”