Fig 7.

A. Pa biofilm supernatant inhibits Af biofilm formation. Af conidia were exposed to serial dilutions of Pa spent medium or sterile distilled water, mixed with fresh RPMI supplemented with 10% serum during Af biofilm formation as described in Methods and Fig 1III. The percent of fresh medium in each test situation was decreased as the spent medium or sterile distilled water increased. Then the resulting XTT readings were quantified, and the results expressed as percent of control with medium alone (no supernatant or distilled water). Results are presented as the mean of three replicates from three strains of Pa performed on two separate occasions. Error bars represent the SD of the mean. B. Pa biofilm supernatant inhibits planktonic Af. Af conidia were exposed to serial dilutions of Pa spent medium or sterile distilled water, mixed with fresh RPMI, and grown planktonically in tubes, as described in Methods. The percent of fresh medium in each tube was decreased as the spent medium or sterile distilled water increased. Then the resulting XTT readings were quantified, and the results expressed as percent of control with medium alone (no supernatant or distilled water). The results shown are with the non-mucoid CF Pa isolate supernatant; the mucoid CF Pa isolate and the non-CF Pa isolate were studied concurrently, and the results were not different; only the non-mucoid Pa result is shown to avoid clutter.