Documents Relating Lethality of Ozone on Listeria monocytogenes
Document 1, from the journal of Applied and Environmental Microbiology, of the
American Society for Microbiology is a research paper funded by the U.S. Department of
Agriculture examining the Efficacy of Ozonated Water against Various Food-Related
Microorganisms. Besides concluding that Ozone is especially lethal against a variety of
bacteria, among gram-positive bacteria, Listeria monocytogenes (L. monocytogenes) is
significantly more sensitive to Ozone than other strains tested. Characteristic of their
results is that more than 4 log units of L. monocytogenes cells per ml were killed
instantaneously by ozone concentrations of 0.15 to 0.20 mg/liter either in the absence or
presence of added organic material.
Document 2, also from the journal of Applied and Environmental Microbiology, is a
subsequent study carried out at the University of Illinois, and confirms the lethality of
Ozone on L. monocytogenes. However, this study examined the efficacy of Ozone at
differing concentrations and at differing temperatures on a variety of strains of L.
monocytogenes. Results indicated that although each strain of L. monocytogenes
displays a different sensitivity to Ozone, all strains, including wild and mutant strains can
be deactivated by Ozone. In particular, exposure to Ozone at 1.00 ppm in phosphatebuffered saline at 24°C for 1.5 minutes completely inactivated the strains of L.
monocytogenes. Of course, presence of other organic matter exerts its own Ozone
demands, diminishing the full utilization of the applied dosage.
Document 3 is a Fact-Sheet created by the U.S. Food and Drug Administration from their
Foodborne Pathogenic Microorganisms and Natural Toxins Handbook. This article
describes a number of characteristics and properties of L. monocytogenes and its
observed effects within our population.