FIG 2.

Bactericidal activity against S. aureus requires live C. pseudodiphtheriticum and is contact independent. (a) C. pseudodiphtheriticum cells were heated to 90°C for 10 min and then spotted on BHIT agar seeded with S. aureus 2014.N. (b) A 0.2-μm filter was placed on top of BHIT agar seeded with S. aureus 2014.N, and C. pseudodiphtheriticum was spotted on top of the filter. Images of the ZOC were taken after 24, 48, and 120 h of incubation at 28°C; 24- and 120-hour images are shown in panel a, and 24- and 48-hour images are shown in panel b. Images are representative of three independent biological replicates. Bar, 10 mm. (c) S. aureus strains 2014.N, LAC, and Mu50 were spread on the agar surface, and a sterile disk was placed in the center of the plate. Fifty microliters of concentrated CCFM prepared from C. pseudodiphtheriticum was inoculated onto the disk and allowed to dry. Images of the ZOC were taken after 24 and 72 h of incubation. Images are representative of three independent biological replicates. Bar, 10 mm.