(93ag) Dipicolinic Acid Released from Spores Treated with Supercritical Co2 and 200ppm H2O2

This project supports research on using supercritical CO₂ for sterilization of bacterial spores. Spore deactivation has significant implications as a new method of sterilizing biomaterials and medical devices. The specific purpose of this work is to quantify dipicolinic acid (DPA) release from both B. anthracis and B. antrophaeus spores exposed to a supercritical CO₂ process. DPA release gives insight on the mechanism of CO₂-based sterilization. DPA is a marker for spore coat perforation and, its releases indicate rupture of the spore core and the surrounding peptidoglycan layer. In addition, because the genome of B. anthracis is mapped, the mechanism of this new sterilization technique can be further investigated on a molecular level. Lyophilized spores were exposed to varying pressures and treatment times (4000 psi, 4 hours; 1500 psi, 1 hour) at 40°C. DPA was quantified by a fluorescence method sensitive to ppb levels. Comparison to untreated controls confirms perforation of the spore coat. Also, both a higher pressure and a longer treatment time were more effective. B. anthracis spores release less DPA than B. atrophaeus; thus, the spore coat of B. anthracis is more difficult to perforate.