Figure 1.
Participation of MEP-dependent isoprene biosynthesis pathway into two modules.
Gene symbols and the enzymes they encode (all genes were from E. coli except where noted): dxs, DXP synthase; ispC, DXP reductionisomerase; ispD, DXP-ME synthase; ispE, CDP-ME kinase; ispF, MECPP synthase; ispG, HMBPP synthase; ispH, HMBPP reductase; idi, IPP isomerase; ispS, isoprene synthase (P. alba). Pathway intermediates: G3P, glyceraldehyde-3-phosphate; DXP, 1-deoxy-D-xylulose 5-phosphate; MEP, 2-C-methyl-D-erythritol 4-phosphate; CDP-ME, 4-diphosphocytidyl-2-C-methyl-D-erythritol; CDP-MEP, 4-diphosphocytidyl-2-C-methyl-D-erythritol 2-phosphate; MECPP, 2-C-methyl-D-erythritol 2,4-cyclopyrophosphate; HMBPP, 1-hydroxy-2-methyl-2-(E)-butenyl 4-pyrophosphate; IPP, isopentenyl pyrophosphate; DMAPP, dimethylallyl pyrophosphate; DHAP, dihydroxyacetone 3-phosphate.
Figure 2.
Four glycolytic pathways present in E. coli.
EMP, Embden-Meyerhof pathway; PPP, pentose phosphate pathway; EDP, Entner-Doudoroff pathway.
Figure 3.
Isoprene titers and yields from different feeding modules.
Module 1, EMP of strain FMIS 1; Module 2, EDP+PPP of strain FMIS 2; Module 3, EDP of strain FMIS 3, these three strains used glucose as carbon source. Module 4, PPP of strain FMIS 4; Module 5, Dahms pathway of strain FMIS 5, these two strains used D-xylose as carbon source. All strains are listed in Table S1 in File S1. A 160 mL serum bottle containing 40 mL of semi-defined medium, consisted of M9 salts, 5 g L−1 yeast extract, 10 g L−1 required carbon source and 1 mM thiamine pyrophosphate (TPP), was used for the cultivation of the strains for isoprene production.
Table 1.
Substrate consumption, isoprene and biomass productions from different feeding modulesa.
Figure 4.
Pyruvate and G3P generation, energy and reducing equivalents production of different glycolytic pathways.