Methods and Compositions for the Extracellular Transport of Biosynthetic Hydrocarbons and Other Molecules
The present disclosure identifies methods and compositions for modifying photoautotrophic organisms as hosts, such that the organisms efficiently convert carbon dioxide and light into hydrocarbons, e.g., n-alkanes and n-alkenes, wherein the n-alkanes are secreted into the culture medium via recombinantly expressed transporter proteins. In particular, the use of such organisms for the commercial production of n-alkanes and related molecules is contemplated.
1 .- 81 . (canceled)
82 . A method for producing hydrocarbons, comprising:
(i) culturing an engineered photosynthetic microorganism in a culture medium, wherein said engineered photosynthetic microorganism comprises (i) genes encoding a recombinant acyl-ACP reductase enzyme (AAR) and a recombinant alkanal deformylative monooxygenase (ADM) enzyme, and (ii) one or more recombinant genes encoding one or more protein components of a recombinant hydrocarbon ATP-binding cassette (ABC) efflux pump system; and
(ii) exposing said engineered photosynthetic microorganism to light and an inorganic carbon source, wherein said exposure results in the conversion of said inorganic carbon source by said engineered photosynthetic microorganism into n-alkanes, wherein said n-alkanes are secreted into said culture medium in an amount greater than that secreted by an otherwise identical photosynthetic microorganism, cultured under identical conditions, but lacking said recombinant genes.
83 . The engineered photosynthetic microorganism of claim 82 , wherein said one or more protein components are selected from the group consisting of YbhG, YbhF, YbhS, YbhR, YhiI, RbbA, YhhJ, TolC and TolC homolog protein components.
84 . The method of claim 82 , wherein said n-alkanes comprise predominantly n-heptadecane, n-pentadecane or a combination thereof.
85 . The method of claim 82 , further comprising isolating at least one of said n-alkanes, an n-alkene or an n-alkanol from said culture medium.
86 . The method of claim 82 , wherein at least one of said recombinant genes is encoded on a plasmid.
87 . The method of claim 82 , wherein at least one of said recombinant genes is incorporated into the genome of said engineered photosynthetic microorganism.
88 . The method of claim 82 , wherein at least one of said recombinant genes is present in multiple copies in said engineered photosynthetic microorganism.
89 . The method of claim 82 wherein at least two of said recombinant genes are part of an operon, and wherein the expression of said genes is controlled by a single promoter.
90 . The method of claim 82 , wherein at least 95% of said n-alkanes are n-pentadecane and n-heptadecane.
91 . The method of claim 82 , wherein the expression of at least one of said recombinant genes is controlled by one or more inducible promoters.
92 . The method of claim 91 , wherein at least one promoter is a urea-repressible, nitrate-inducible promoter.
93 . The method of claim 91 , wherein said promoter is a nirA-type promoter.
94 . The method of claim 93 , wherein said nirA-type promoter is P(nir07) or P(nir09).
95 . The engineered photosynthetic microorganism of claim 82 , wherein said one or more protein components are selected from the group consisting of YbhG, YbhF, YbhS, YbhR, YhiI, RbbA, YhhJ and TolC protein components, wherein the leader sequences of said YbhG, YbhS, YbhR, YhiI, TolC and TolC homolog protein components are non-native leader sequences.
96 . The engineered photosynthetic microorganism of claim 82 , wherein said one or more protein components are selected from the group consisting of YbhG, YbhF, YbhS, YbhR, YhiI, RbbA, YhhJ, TolC and TolC homolog protein components, wherein the leader sequences of said YbhG, YhiI, TolC and TolC homolog protein components are leader sequences native to said photosynthetic microorganism.
97 . The engineered photosynthetic microorganism of any of claims 83 , 95 or 96 , wherein said TolC homolog protein is selected from the group consisting of SYNPCC7002_A0585 or Synpcc7942 — 1761.