Fig. 4.

3HB production in fed-batch cultivations of E. coli AF1000 expressing either t3-rx-zwf or t3-rx-zwf-yciA under either ammonium-reduced or depleted conditions. a NH₄⁺-reduced conditions for AF1000 harboring pJBGT3RX and pBAD-(Km)-zwf, reference cultivation. b NH₄⁺-reduced conditions for AF1000 harboring pJBGT3RX and pBAD-(Km)-zwf-yciA. c NH₄⁺-depleted conditions for AF1000 harboring pJBGT3RX and pBAD-(Km)-zwf, reference cultivation. d NH₄⁺-depleted conditions for AF1000 harboring pJBGT3RX and pBAD-(Km)-zwf-yciA. The shown parameters are cell dry weight (CDW, open squares), glucose (Glc,open circles), ammonium (NH₄⁺, filled triangles), acetic acid (HAc, crosses), and (R)-3-hydroxybutyrate (3HB, filled diamonds). One representative replicate from a set of duplicates is shown in the figure, with duplicates included as Fig. S3 in Supplementary Material. Specific production rates (q_3HB) and volumetric rates (r_3HB) are represented as functions obtained from least square fits of the data and are shown for both replicate experiments. All parameters were linearly fit, with the exception of CDW, which was fit with a third order polynomial. The dashed vertical line marks the shift between batch phase and fed-batch phase with feed of the respective reduced nutrient and glucose. The arrow indicates the time of induction