Fig. 3

Metabolic analysis of the mutant strain E. coli in response to PN overproduction between the early and late stages of fermentation. (A) Amino acid analysis. (B) Chemical analysis of the TCA cycle. Among the two adjacent squares, the squares on the left represent changes occurring in the early phase (from 6 to 16 h), while the squares on the right represent changes occurring in the late phases (from 36 to 42 h). The experiments were conducted in triplicate, and the significance (p value) was evaluated by two-sided Student’s t test. * P < 0.05; ** P < 0.01; ***P < 0.001; **** P < 0.0001