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Figure 3 | Microbial Cell Factories

Figure 3

From: Factors affecting plasmid production in Escherichia coli from a resource allocation standpoint

Figure 3

Maximum plasmid yield and other key fluxes as a function of α. (A-C) Maximum plasmid yield for different r acetate and r Pyk scenarios, variable limits on Bla production, and r transhydrogenase = 0. The fluxes r acetate and r Pyk were: (A) unconstrained, but adopted values of zero, (B) set to JM101 (wild-type) values, or (C) fixed at PB25 (Pyk-deficient) values. Solid lines: No upper limit imposed on Bla production. Dashed lines: Bla production limited to selected percentages of total protein. Yield decreases as a function of promoter strength α along a solid line if Bla production is unconstrained. When Bla production is limited to a particular percentage, the yield decreases along a solid line until it becomes independent of α at its respective flat dashed line. (D) Effect of transhydrogenase activity on plasmid yield. Solid lines: Redrawn from (A-C) for comparison where unconstrained (black), PB25 (red), and JM101 (blue) values for r acetate and r Pyk are assumed, and r transhydrogenase = 0. Dashed lines:Increased maximum plasmid yield for unconstrained (black), PB25 (red), and JM101 (blue) cases when r transhydrogenase > 0 per Equation (10). (E) HMP:glycolysis flux ratio when r transhydrogenase = 0 (solid lines) or when r transhydrogenase > 0 per Equation (10) (dashed lines). Contrasted are the unconstrained (black), PB25 (red), and JM101 (blue) cases. (F) Ppc flux as % glucose uptake when r transhydrogenase = 0 (solid lines) or > 0 (dashed lines). Cases compared and color coding as in (D) and (E).

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