FIG. 2.

Growth and yadBC promoter activity from yadBC-lacZ integrated within invA in the chromosome of Y. pestis CO99-3015.S10. Y. pestis CO99-3015.S10 and the negative control strain Y. pestis CO99-3015.S4 with promoterless lacZ integrated into invA were grown at 26 and 37°C, and the OD₆₂₀ and β-galactosidase activity were determined at the indicated times. β-Galactosidase levels (expressed in Miller units) were determined for yersiniae grown at 26°C (▴) and at 37°C (▪); corresponding OD₆₂₀ values are also shown (▵ and □, respectively). The open circles show β-galactosidase activity at 37°C for Y. pestis CO99-3015.S4. Essentially identical data were obtained for this strain grown at 26°C, and the growth data for this strain overlapped those for Y. pestis CO99-3015.S10 (data not shown). The experiments were done three times on different days with similar results. The data shown are data from one experiment, and the error bars indicate the ranges for duplicate samples.