Figure 3

Fed-batch strategy using acetic acid as stimulator for P4HB synthesis in E . coli JM109 (pKSSE5.3) grown on modified M9 medium supplemented with 20gL ^-1 glycerol, 6gL ^-1 Na-4HB, 0.5gL ^-1 NZ-amine, 0.015gL ^-1 thiamine and 100mgL ^-1 ampicillin. Acetic acid was added at different physiological states. For all cultures pulse-feeding started at 40h of cultivation: T=40.5h, addition of 12gL^-1 glycerol and 6gL^-1 Na-4HB; T=45.75h, addition of 20gL^-1 glycerol; T=63.75h, addition of 10gL^-1 glycerol and 3gL^-1 Na-4HB; T=72.25h, addition of 20gL^-1 glycerol and 6gL^-1 Na-4HB; T=76.75h, addition of 10gL^-1 glycerol. Culture A, addition of 2gL¹ acetic acid at the beginning of the cultivation; Culture B, addition of 1gL¹ acetic acid at beginning and at the end of growth phase (66h), respectively; Culture C, addition of 2gL¹ acetic acid after 48h cultivation; Culture D, no addition of acetic acid to the culture. Arrows represent the addition of acetic acid. The data are the average numbers of duplicates.