Figures 4 & 5

Figure 4: Effect of Growth-Medium [NaCl] on the Induction of the Lac-Operon. Approxi-mately 2x10⁸ early log-phase E. coli cells grown in 0.5% lactose Luria Broth were permeablized with violent aggitation with SDS and chloroform. ONPG was added and the development of yellow was assayed spectrophotometrically at 420 nm. The data gathered here are normalized on the basis of initial absorbance at 550 nm. The slopes are proportional to [lactase].

Figure 5: Effect on Growth-Medium [NaCl] on [Lactase]. The slopes derived from the previous figure were normalized to the control and then plotted versus percent NaCl (w/v).