Hybrid organic-inorganic system for producing biofuels
The present invention provides for a system for converting CO 2 and H 2 to one or more biologically derived compounds. In some embodiments, the system comprises a host cell comprising one or more nucleic acids encoding genes for a recombinant surface display protein which is capable of tethering an electrocatalyst molecule, such as a cobalt(II) complex supported by tetradentate polypyridyl ligand 2-bis(2-pyridyl)(methoxy)methyl-6-pyridylpyridine (PY4), and enzymes for synthesizing a biologically derived compound, such as an alkane, alcohol, fatty acid, ester, or isoprenoid.
1. A host cell comprising: (a) a first membrane-bound protein or peptide bound directly or indirectly to an electrocatalyst molecule, (b) enzymes capable of synthesizing a biologically derived compound, and (c) optionally a second protein or peptide bound to the electrocatalyst molecule, wherein the first protein or peptide is bound to the second protein or peptide; wherein the host cell is Escherichia coli or of the genus Ralstonia , and the electrocatalyst molecule is a cobalt(II) complex supported by tetradentate polypyridyl ligand 2-bis(2-pyridyl)(methoxy)methyl-6-pyridylpyridine (PY4) or a CdSe/ZnS nanoparticle; wherein the biologically derived compound is an alkane, alcohol, fatty acid, ester, or isoprenoid.
2. The host cell of claim 1 , further comprising one or more nucleic acids encoding genes for the first protein or peptide, enzymes for synthesizing a biologically derived compound, and optionally the second protein or peptide.
3. The host cell of claim 1 , wherein the first and/or second protein or peptide is translocated to or outside of the outer membrane of the host cell upon expression within the host cell.
4. The host cell of claim 1 , wherein the electrocatalyst molecule is a cobalt(II) complex supported by a CdSe/ZnS nanoparticle.
5. The host cell of claim 1 , wherein the host cell is of the genus Ralstonia.
6. The host cell of claim 5 , wherein the host cell is R. basilensis, R. campinensis, R. eutropha, R. gilardii, R. insidiosa, R. mannitolilytica, R. metallidurans, R. paucula, R. pickettii, R. respiraculi, R. solanacearum, R. syzygii , or R. taiwanensis.
7. The host cell of claim 6 , wherein the host cell is R. eutropha H16.
8. The host cell of claim 1 , wherein the first protein or peptide is Escherichia coli FhuA and the second protein or peptide is bacteriophage λ pb5.
9. The host cell of claim 1 , wherein the host cell is capable of growing to a cell density of equal to or more than 200 g/L.
10. The host cell of claim 1 , wherein the enzymes capable of synthesizing a biologically derived compound comprise: enzymes of an acyl-ACP reductase/aldehyde decarbonylase pathway, a thioesterase, enzymes of a mevalonate-dependent (MEV) isoprenoid pathway, enzymes of a deoxyxylulose 5-phosphate (DXP) pathway, an amophadiene synthase, a farnesene synthase, a bisabolene synthase, or a squalene synthase.
11. The host cell of claim 10 , wherein the enzymes capable of synthesizing a biologically derived compound comprise a thioesterase, and the biologically derived compound is a fatty acid.
12. The host cell of claim 10 , wherein the enzymes capable of synthesizing a biologically derived compound comprise enzymes of the acyl-ACP reductase/aldehyde decarbonylase pathway, and the biologically derived compound is an alkane.
13. The host cell of claim 10 , wherein the enzymes capable of synthesizing a biologically derived compound comprise enzymes of the mevalonate-dependent (MEV) isoprenoid pathway, and the biologically derived compound is an isoprenoid.
14. The host cell of claim 10 , wherein the enzymes capable of synthesizing a biologically derived compound comprise enzymes of the DXP pathway, and the biologically derived compound is an isoprenoid.
15. The host cell of claim 10 , wherein the enzymes capable of synthesizing a biologically derived compound comprise an amophadiene synthase, farnesene synthase, bisabolene synthase, or squalene synthase, and the biologically derived compound is an amophadiene, farnesene, bisabolene, or squalene, respectively.