Sterilizing Bacillus pumilus spores using supercritical carbon dioxide

Supercritical carbon dioxide (SC CO2) has been evaluated as a new sterilization technology. Results are presented on killing of B. pumilus spores using SC CO2 containing trace levels of additives. Complete killing was achieved with 200 part per million (ppm) hydrogen peroxide in SC CO2 at 60 °C, 27.5 MPa. Addition of water to SC CO2 resulted in greater than three-log killing, but this is insufficient to claim sterilization. Neither ethanol nor isopropanol when added to SC CO2 affected killing.