14C Analysis of Protein Extracts from Bacillus Spores

Investigators of bioagent incidents or interdicted materials need validated, independent analytical methods that will allow them to distinguish between recently made bioagent samples versus material drawn from the archives of a historical program. Heterotrophic bacteria convert the carbon in their food sources, growth substrate or culture media, into the biomolecules they need. The F 14 C (fraction modern radiocarbon) of a variety of media, Bacillus spores, and separated proteins from Bacillus spores was measured by accelerator mass spectrometry (AMS). AMS precisely measures F 14 C values of biological materials and has been used to date the synthesis of biomaterials over the bomb pulse era (1955 to present). The F 14 Co fBacillus spores reflects the radiocarbon content of the media in which they were grown. In a survey of commercial media we found that the F 14 C value indicated that carbon sources for the media were alive within about a year of the date of manufacture and generally of terrestrial origin. Hence, bacteria and their products can be dated using their 14 C signature. Bacillus spore samples were