FIG. 1.

Survival of wild-type and type II secretion mutant L. pneumophila in tap water at 37°C, 25°C, and 17°C. Wild-type strain 130b, pilD mutant NU272, lspF mutant NU275, and lspDE mutant NU258 were inoculated at comparable levels into sterile tap water, and then the samples were incubated at either 37°C (top), 25°C (middle), or 17°C (bottom). On the indicated days, the numbers of CFU in the samples, presented as means and standard deviations, were determined by plating aliquots on BCYE agar.