FIG 5.

D. pigrum and C. pseudodiphtheriticum grown together but not D. pigrum alone inhibited S. pneumoniae in an in vitro agar medium-based assay. Representative images are shown of S. pneumoniae 603 growth on (A) BHI medium alone or on CFCAM from (B) C. pseudodiphtheriticum KPL1989, (C) D. pigrum KPL1914, or (D) both D. pigrum and C. pseudodiphtheriticum grown in a mixed inoculum (n = 4). To condition the medium, we cultivated D. pigrum and/or C. pseudodiphtheriticum on a membrane, which was then removed prior to spreading a lawn of S. pneumoniae. For monoculture, 100 μl of either D. pigrum or C. pseudodiphtheriticum, resuspended to an OD₆₀₀ = 0.50, were inoculated onto the membrane. For mixed coculture, 50 μl of D. pigrum (OD₆₀₀ = 0.50) were mixed with 50 μl of C. pseudodiphtheriticum (OD₆₀₀ = 0.50) to yield a final volume of 100 μl for the inoculum, such that each bacterial species was present in the coculture inoculum at half the amount used for the corresponding monoculture inoculum. Images were cropped. Black marks indicate edges where the membrane had been.