Researchers from the National Institute of Standards and Technology (NIST) and the U.S. Army Dugway (Utah) Proving Ground have developed reliable methods based on DNA analysis to assess the concentration and viability of anthrax spores after prolonged storage. The techniques and data are essential steps in developing a reliable reference standard for anthrax detection and decontamination.
Bacillus anthracis, the bacterium that causes anthrax, has been a centuries-old threat to human health. In 2001, it was used as a letter-borne terrorist weapon that killed five Americans. Since the tenacious bacterium can survive for decades in a stable spore state, the Department of Homeland Security (DHS) has been working with NIST to develop anthrax spore reference materials. These materials could be used as controls in laboratory studies of anthrax, to calibrate spore detection equipment and to assess the efficiency of spore decontamination methods.
Because sample stability is a key requirement for reference materials, NIST and Army researchers recently compared different methods for measuring the concentration, biological activity and stability of laboratory-grade Bacillus anthracis spores under different storage conditions. Bacillus anthracis (Sterne), a harmless vaccine strain, was used in the study. The results of the research will be published in an upcoming issue of the Journal of Applied Microbiology.*
Working with samples that had been stored up to 2 1/2 years, the research team used two classic microbiological techniques to quantify the Bacillus anthracis concentrations: counting spores under a microscope and counting the bacterial colonies that grow after the spores are spread on a nutrient surface and germinate. The latter yields valuable data on the biological activity of the samples; however, only viable cells are counted and counts may be underestimated if cell clumping occurs. A better approach is to measure the amount of gen
|Contact: Michael E. Newman|
National Institute of Standards and Technology (NIST)