TABLE 1.
Hemolytic activitya
| Strain | Mean no. of HU (SD) |
|---|---|
| 10403S (wild type) | 130.7 (19.9) |
| DP-L2161 (LLO negative) | NDb |
| DP-L3885 (iLLO) | |
| IPTG concn (mM) | |
| 0 | 2.8 (1.5) |
| 0.001 | 5.2 (0.8) |
| 0.005 | 12.5 (3.5) |
| 0.01 | 23.5 (9.0) |
| 0.02 | 47.5 (10.4) |
| 0.03 | 62.4 (9.1) |
| 0.04 | 70.5 (9.2) |
| 0.05 | 81.4 (13.1) |
| 0.1 | 107.9 (21.1) |
| 0.25 | 120.8 (23.4) |
| 0.5 | 129.8 (21.1) |
| 1.0 | 132.9 (26.3) |
| 10 | 133.3 (20.9) |
a
An overnight culture of iLLO strain DP-L3885 was diluted 1:10 in BHI broth into replicate flasks and grown for 5 h at 37°C in the presence of various concentrations of IPTG. The OD600 values of all of the cultures were identical. Wild-type strain 10403S and LLO-negative strain DP-L2161 were grown under similar conditions in the absence of IPTG. Hemolytic activity of culture supernatants was assayed as described in Materials and Methods. Numbers of HU are expressed as the reciprocal of the dilution of culture supernatant that yielded 50% hemolysis. The means of three experiments performed on separate days are shown.
b
ND, not detectable (<1 HU).