Methods and compositions for the recombinant biosynthesis of n-alkanes

Abstract

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.

What is claimed is: 
     
         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.