FIG. 4.

Utilization of erythrocytes as a sole nutrient source for growth of wild-type P. aeruginosa KU2 and the lepA and plcH mutants. The growth of each P. aeruginosa strain was measured after 24 h of incubation at 37°C using an Alamar blue reagent. Alamar blue was added to the sample and incubated at 37°C for 8 h. After the incubation, the absorbance of Alamar blue at 570 and 590 nm was measured. The growth level of each P. aeruginosa strain was expressed as the absorbance of reduced Alamar blue at 570 nm minus the absorbance of oxidized Alamar blue at 595 nm. Values represent the mean results ± standard deviations from triplicate determinations. The data from a representative experiment are presented, and similar results were obtained in three independent experiments. The difference between the growth of KU2ΔlepA and KU2ΔplcH was not significant. The differences of all the other pairings were significant with P values of <0.01.