FIG. 5.

Vero cell cytotoxicity of 20-h supernatants from transformed enteric bacteria. A, E. coli O157:H7 (positive control); B, E. coli JM109 (negative control); C, Salmonella serovar Enteritidis (negative control); D, E. coli O157:H7 vesicles; E, E. coli JM109, vesicle transformed; F, Salmonella serovar Enteritidis, vesicle transformed; G, E. coli JM109 transformed with total DNA purified from E. coli O157:H7; H, E. coli JM109 transformed with lysozyme-treated vesicles; I, E. coli JM109 transformed with proteinase K-treated vesicles. Values were determined as described in Materials and Methods. Error bars indicate the standard errors of the means. The assay was performed in triplicate and repeated twice. Values are from a representative experiment.