Methods and compositions for the recombinant biosynthesis of n-alkanes
The present disclosure identifies methods and compositions for modifying photoautotrophic organisms as hosts, such that the organisms efficiently convert carbon dioxide and light into n-alkanes, and in particular the use of such organisms for the commercial production of n-alkanes and related molecules.
1. A method for producing hydrocarbons, comprising:
(i) culturing an engineered photosynthetic microbe in a culture medium, wherein said engineered photosynthetic microbe comprises a recombinant acyl-ACP reductase enzyme and a recombinant-alkanal decarboxylative monooxygenase enzyme; and
(ii) exposing said engineered photosynthetic microbe to light and an inorganic carbon source, wherein said exposure results in the conversion of inorganic carbon by said engineered photosynthetic microbe into alkanes, wherein at least one of said alkanes is selected from the group consisting of tridecane, tetradecane, pentadecane, hexadecane, and heptadecane, and wherein the amount of said alkanes produced is at least two times greater than that produced by an otherwise identical microbe lacking said recombinant enzymes and cultivated under identical conditions.
2. The method of claim 1 , wherein at least one of said recombinant enzymes is heterologous with respect to said engineered photosynthetic microbe.
3. The method of claim 1 , wherein said engineered photosynthetic microbe further produces at least one alkene or alkanol.
4. The method of claim 3 , wherein said engineered photosynthetic microbe produces at least one alkene or alkanol selected from the group consisting of pentadecene, heptadecene, and octadecanol.
5. The method of claim 3 , wherein said alkanes comprise predominantly heptadecane, pentadecane or a combination thereof
6. The method of claim 3 , further comprising isolating at least one alkane, alkene or alkanol from said engineered photosynthetic microbe or said culture medium.
7. The method of claim 1 , wherein at least one of said recombinant enzymes is encoded by a plasmid.
8. The method of claim 1 , wherein at least one of said recombinant enzymes is encoded by a recombinant gene incorporated into the genome of said engineered photosynthetic microbe.
9. The method of claim 1 , wherein at least one of said recombinant enzymes is encoded by a gene which is present in multiple copies in said engineered photosynthetic microbe.
10. The method of claim 1 , wherein said recombinant enzymes are encoded by genes which are part of an operon, and wherein the expression of said genes is controlled by a single promoter.
11. The method of claim 1 , wherein said recombinant acyl-ACP reductase and alkanal decarboxylative monooxygenase enzymes are at least 95% identical to SEQ ID NO: 6 and SEQ ID NO: 8, respectively.
12. The method of claim 1 , wherein said recombinant acyl-ACP reductase and alkanal decarboxylative monooxygenase enzymes are at least 95% identical to SEQ ID NO: 10 and SEQ ID NO: 12, respectively.
13. The method of claim 10 , wherein said recombinant acyl-ACP reductase and alkanal decarboxylative monooxygenase enzymes are at least 95% identical to SEQ ID NO: 6 and SEQ ID NO: 8, respectively.
14. The method of claim 10 , wherein said recombinant acyl-ACP reductase and alkanal decarboxylative monooxygenase enzymes are at least 95% identical to SEQ ID NO: 10 and SEQ ID NO: 12, respectively.
15. The method of claim 1 , wherein said engineered photosynthetic microbe is a thermophilic microbe.