Figure 2

Effect of zinc acetate on LEE gene expression. β-Galactosidase activities derived from plasmid pJLM165, LEE4-lacZfusion in strains MC4100 (A), JPN15 (B), E2348/69 (C) and LRT9 (D); and plasmid pJLM164, LEE1-lacZfusion in strains MC4100 (E), JPN15 (F), E2348/69 (G) and LRT9 (H) were monitored in the presence and absence of zinc in the tissue culture medium DMEM. Overnight cultures grown in LB were inoculated by 1:100 dilution into DMEM buffered with 25 mM HEPES, pH 7.4, and 50 μg/ml kanamycin in the presence and absence of zinc acetate and harvested with OD₆₀₀ of 0.3 to 0.5 in exponential growth. Activities were significantly greater in the 0 mM versus 0.5 mM zinc acetate conditions (A-H) for all cultures tested (Student’s t-test, p-value <0.05).