Deibel, R. H. (American Meat Institute Foundation, Chicago, Ill.), and J. H. Silliker. Food-poisoning potential of the enterococci. J. Bacteriol. 85:827–832. 1963.—A total of 23 enterococcus strains were fed to two and sometimes three human volunteers in an effort to elicit food-poisoning symptoms. Each culture was consumed after it was grown in whole sterile milk or on the surface of commercially sterile ham slices. Six strains of Streptococcus faecalis var. liquefaciens were consumed after complete liquefaction of gelatin. In addition, strains of S. faecalis were consumed after having been grown in media which altered the energy metabolism (arginine, gluconate, malate, and pyruvate). In no instance were any of the above conditions of growth conducive to the production of food-poisoning symptoms in the volunteers. Moreover, no evidence was found to indicate that either the age of the culture or the disruption of the cell was a factor in the production or release of a toxic principle. It would appear that until the environmental conditions (if any) for food poisoning are defined the evidence obtained suggests that the association of enterococci and food poisoning is questionable.