Fig. 3.
Biofuel production with constant efflux pump expression. a Expression of pumps can reduce intracellular biofuel levels, reducing toxicity. b Overexpressing efflux pumps inhibits cell growth. Experimental data (dots) and a model (line) of this phenomenon for the srpABC efflux pump from Pseudomonas putida S12. γp = 0.14 from the model fits; note that this value is specific to srpABC in E. coli and other pumps and organisms may have different toxicity profiles. c Simulation of cell growth and biofuel production with export using efflux pumps. Simulation parameters are the same as listed in Fig. 2 with δb = 0.5 1/M h, k p = 0.12 1/h, βp = αn, γp = 0.14