FIG. 1.

Effect of CSP2 on in vitro growth of S. pneumoniae TIGR4 and its comD mutant, FP184. Bacterial strains TIGR4 and FP184 (comD negative) were inoculated 1/100 in liquid medium, and their growth was monitored by measurement of the density of the culture. When the culture reached an OD of 0.05, 15 ml of culture was aliquoted and placed in three tubes, one without CSP2 (open squares, TIGR4; filled squares, FP184), one with 100 ng of CSP2/ml (in vitro transforming dose) (filled triangles, TIGR4; open triangles, FP184), and one with 1,000 ng of CSP2/ml (in vivo dose) (filled circles connected by a straight line, TIGR4; open circles, FP184). The time of addition of CSP2 to the cultures is shown by an arrow.