FIG. 3.

Origin of key metabolic intermediates in E. coli global regulator mutants during continuous, glucose-limited growth. The fraction of serine derived through the EMP pathway and the fraction of pyruvate derived through the ED pathway were obtained from experiments with 50% [1-¹³C]glucose and 50% natural glucose. All other ratios were from experiments with 20% [U-¹³C]glucose and 80% natural glucose. For [U-¹³C]glucose experiments, the bars represent the average of two to four independent cultivations and the error is the standard deviation. For all [1-¹³C]glucose experiments, the bars represent a single experiment and error bars are the experimental error calculated from redundant mass distribution (13, 35). The light gray boxes indicate the range of values obtained from three experiments with the parent strain.