FIG 5.

Culture temperature-dependent variation of TF concentration. E. coli K-12 W3110 was grown in LB-glucose medium at various temperatures (22, 27, 32, 37, and 42°C). Cells were harvested in the middle of exponential phase (OD₆₀₀, 0.4). Cell lysate was prepared by method A (see Materials and Methods), and TF concentration was determined by the quantitative immunoblot method as described in Materials and Methods. The temperature-dependent change was classified into four types: (A) TA group, TF level increased with the increase in culture temperate within the range of 22 to 42°C; (B) TB group, TF level stays constant between the culture temperature 22 and 42°C; (C) TC group, the intracellular level is either maximum or minimum at intermediate temperature (32 to 37°C); (D) TD group, TF level increases with the decrease in culture temperature from 42 to 22°C. Error bars show standard errors of the means from triplicate or quadruplicate determinations.