FIG. 3.

Secretion, accumulation, and substrate specificity of a L. pneumophila esterase-lipase. (A) 130b (black columns) and NU243 (white columns) were grown in BYE broth, and then, at late log phase, culture supernatants (left) and cell lysates (right) were examined for their ability to cleave p-nitrophenyl caprylate. (B) In a separate experiment, late-log supernatants from wild-type and pilD mutant cultures were compared for their ability to cleave p-nitrophenyl caprylate (pNPC) (left) versus p-nitrophenyl palmitate (pNPPa) (right). The values presented are the mean and standard deviations from triplicate cultures. For both the supernatant and lysate comparisons, the differences between 130b and NU243 activity were significant (P < 0.001, Student's t test). The results obtained in panel A were observed on six other occasions, while those in panel B were seen in two other experiments.