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 cyanobacterium in a culture medium, wherein said engineered cyanobacterium comprises a recombinant AAR enzyme and a recombinant ADM enzyme; and
(ii) exposing said engineered cyanobacterium to light and carbon dioxide, wherein said exposure results in the conversion of said carbon dioxide by said engineered cynanobacterium into n-alkanes, wherein at least one of said n-alkanes is selected from the group consisting of n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, and n-heptadecane, and wherein the amount of said n-alkanes produced is between 0.1% and 5% dry cell weight and at least two times the amount produced by an otherwise identical cyanobacterium, cultured under identical conditions, but lacking said recombinant AAR and ADM enzymes.
2 . The method of claim 1 , wherein at least one of said recombinant enzymes is heterologous with respect to said engineered cyanobacterium.
3 . The method of claim 1 , wherein said engineered cyanobacterium further produces at least one n-alkene or n-alkanol.
4 . The method of claim 3 , wherein said engineered cyanobacterium produces at least one n-alkene or n-alkanol selected from the group consisting of n-pentadecene, n-heptadecene, and 1-octadecanol.
5 . The method of claim 3 , wherein said n-alkanes comprise predominantly n-heptadecane, n-pentadecane or a combination thereof.
6 . The method of claim 3 , further comprising isolating at least one n-alkane, n-alkene or n-alkanol from said engineered cyanobacterium or said culture medium.
7 . The method of claim 1 , wherein said enzymes are encoded by a plasmid.
8 . The method of claim 1 wherein said enzymes are encoded by recombinant genes incorporated into the genome of said engineered cyanobacterium.
9 . The method of claim 1 wherein said enzymes are encoded by genes which are present in multiple copies in said engineered cyanobacterium.
10 . The method of claim 1 wherein said 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 . A composition comprising an n-alkane produced by the method of claim 1 .
12 . A composition comprising an n-alkene or n-alkanal produced by the method of claim 3 .
13 . An engineered cyanobacterium, wherein said engineered cyanobacterium comprises a recombinant AAR enzyme and a recombinant ADM enzyme.
14 . The engineered cyanobacterium of claim 13 , wherein exposure of the engineered cyanobacterium to light and inorganic carbon results in the conversion of said carbon by said engineered cynanobacterium into n-alkanes, wherein at least one of said n-alkanes is selected from the group consisting of n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, and n-heptadecane, and wherein the amount of said n-alkanes produced is between 0.1% and 5% dry cell weight and at least two times the amount produced by an otherwise identical cyanobacterium, cultured under identical conditions, but lacking said recombinant AAR and ADM enzymes.