Metabolic engineering for microbial production of terpenoid products
In various aspects and embodiments, the invention relates to bacterial strains and methods for making terpene and terpenoid products. The invention provides bacterial strains with improved carbon flux through the MEP pathway, to thereby increase terpene and/or terpenoid product yield by fermentation with carbon sources such as glucose.
1. A bacterial strain comprising:
a recombinant terpenoid synthesis pathway comprising a terpene synthase, the bacterial strain producing isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) through the methylerythritol phosphate (MEP) pathway, and converting the IPP and DMAPP to a terpene or terpenoid through the recombinant terpenoid synthesis pathway; and
one or more genetic modifications that increase MEP carbon, said genetic modifications comprising
a ryhB deletion or inactivation.
2. The bacterial strain of claim 1 , wherein the strain is a bacterium selected from Escherichia spp., Bacillus spp., Rhodobacter spp., Zymomonas spp., or Pseudomonas spp.
3. The bacterial strain of claim 1 , wherein the strain overexpresses Dxr.
4. The bacterial strain of claim 3 , wherein Dxr is overexpressed by complementation with a recombinant gene or operon comprising dxr.
5. The bacterial strain of claim 1 , wherein the strain overexpresses IspE.
6. The bacterial strain of claim 5 , wherein IspE is overexpressed by complementation with a recombinant gene or operon comprising ispE.
7. The bacterial strain of claim 1 , wherein the strain overexpresses ispG and/or ispH.
8. The bacterial strain of claim 7 , wherein ispG and/or ispH are overexpressed by complementation with a recombinant gene or operon comprising ispG and/or H.
9. The bacterial strain of claim 8 , wherein the strain has a modified IspG enzyme having increased activity with respect to wild type E. coli IspG.
10. The bacterial strain of claim 9 , wherein the IspG enzyme has one, two, three or all of the following mutations: L205V, A210S, G212T, and A213I with respect to SEQ ID NO: 5.
11. The bacterial strain of claim 1 , wherein the bacterial strain has at least one additional copy of dxs and idi expressed as an operon or module.
12. The bacterial strain of claim 11 , wherein the bacterial strain has at least one additional copy of dxs, ispD, ispF, and idi expressed as an operon or module.
13. The bacterial strain of claim 1 , having a modification that decreases expression or activity of IspB.
14. The bacterial strain of claim 1 , having a deletion or inactivation of all or part of the iscR gene, and an inducible or constitutive promoter to drive expression of the genes remaining in the isc operon under conditions used for terpene or terpenoid production.
15. The bacterial strain of claim 1 , wherein MEP enzyme expression or activity is altered or balanced such that 1-deoxy-D-xylulose (DOX) and/or 2-C-methyl-D-erythritol (ME) do not accumulate in the culture above about 2 g/L.
16. The bacterial strain of claim 1 , comprising a mutation in glucose-6-phosphate isomerase (pgi) supporting increased terpenoid titer or MEP carbon.
17. The bacterial strain of claim 15 , wherein the DOX and/or ME do not accumulate above about 1 g/L.
18. The bacterial strain of claim 1 , further comprising an MEP pathway complementation comprising:
a dxr gene; and
ispD, ispE, and/or ispF genes.