An official website of the United States government.
This project tests the hypothesis that spores from avirulent strains can be used as surrogates for B. anthracis spores. To do this, the following objectives will be met: <OL> <LI> Heat resistance of spores in buffer at pH 6.5 and 4.5 will be determined at four temperatures. <LI>Heat resistance of most promising surrogates identified in #1 and B. anthracis spores will be determined in milk and orange juice at four temperatures and compared.
NON-TECHNICAL SUMMARY: The food system in the United States is vulnerable to bioterroristic acts using anthrax spores in widely distributed foods. This project determines if the heat used in food processing would be adequate to kill the spores. It also identifies spores from safe species that can be used anthrax substitutes in future research. <P>
APPROACH: The plan of research is straight-forward. Spores are produced from each of the nine strains in quantities sufficient for the whole project. This minimizes spore-crop-to-spore-crop variation and ensures that the pathogen spores and surrogate spores are made under exactly the same conditions. The D values for each strain are determined at 90C to provide some sense of the variability among the stains and their similarity to virulent B. anthracis. The thermal resistance of spores from surrogate strains having similar D90 values to virulent B. anthracis are then determined (along with all three virulent B. anthracis strains) at three other temperatures. The D and z values of each strain are determined and compared with that of virulent B. anthracis to identify the most promising surrogates. <P>
PROGRESS: 2003/07 TO 2007/01<br>
The most important finding of this period is that virulent strains of B. anthracis grow much faster than any of the proposed surrogate species, including the Sterne strain of B. anthracis. Furthermore, we determined that while many anti-microbial peptides inhibited surrogate strains, only the commercially available antimicrobial peptide nisin inhibited the growth of virulent B. anthracis from spore inocula.
<P>
IMPACT: 2003/07 TO 2007/01<br>
These data are being used by threat assessors to determine if current pasteurization practices are sufficient to neutralize this biothreat, and if not, to what degree they should be adjusted. The data also indicate that while B. anthracis is not unusually heat resistant, not all Bacillus species can be used as surrogates. Thus, these data should aid other investigators in choosing appropriate surrogates. The data will aid in generation of appropriate decontamination protocols in the event that food should become contaminated by B. anthracis. Finally, the rapid growth of B. anthracis relative to surrogates is problematic given their ability to survive pasteurization. Work with antimicrobial peptides further indicated that the blanket use of surrogate without appropriate validation should be avoided.