FIG. 3.

Time course of β-exotoxin I accumulation in the supernatant of B. thuringiensis strain 407-1(Cry⁻)(Pig⁺). Strain 407-1(Cry⁻)(Pig⁺) was cultured in LB medium at 30°C, with shaking at 170 rpm. Growth was monitored by monitoring optical density at 600 nm and was plotted on a logarithmic scale. T₀, the onset of the stationary phase, is indicated on the growth curve. The supernatant was sampled at various times after T₀ (T₁, T₃, T₅, T₇, and T₁₀), plotted on the y axis. β-Exotoxin I concentration measured by HPLC at these time points is expressed in micrograms per milliliter and is represented by vertical bars.