Modified photosynthetic microorganisms for producing triglycerides
This disclosure describes genetically modified photosynthetic microorganisms, including Cyanobacteria, that contain one or more exogenous genes encoding a diacylglycerol acyltransferase, a phosphatidate phosphatase, and/or an acetyl-CoA carboxylase, and which are capable of producing increased amounts of fatty acids and/or synthesizing triglycerides.
1. A modified Cyanobacterium comprising an exogenous polynucleotide encoding a prokaryotic diacylglycerol acyltransferase (DGAT), wherein said modified Cyanobacterium produces a triglyceride, a wax ester or both.
2. The modified Cyanobacterium of claim 1 , wherein said DGAT is an Acinetobacter DGAT, a Streptomyces DGAT, or an Alcanivorax DGAT.
3. The modified Cyanobacterium of claim 2 , wherein said DGAT is an Acinetobacter DGAT.
4. The modified Cyanobacterium of claim 3 , wherein said Acinetobacter DGAT is a Acinetobacter baylii ADP1 diacylglycerol acyltransferase (AtfA), or a biologically active fragment or variant thereof.
5. The modified Cyanobacterium of claim 4 , wherein said AtfA comprises a polypeptide sequence set forth in SEQ ID NO:1 or SEQ ID NO:18.
6. The modified Cyanobacterium of claim 2 , wherein said DGAT is a Streptomyces DGAT.
7. The modified Cyanobacterium of claim 6 , wherein said Streptomyces DGAT is a Streptomyces coelicolor DGAT, or a biologically active fragment or variant thereof.
8. The modified Cyanobacterium of claim 7 , wherein said Streptomyces coelicolor DGAT comprises a polypeptide sequence set forth in SEQ ID NO:14.
9. The modified Cyanobacterium of claim 2 , wherein said DGAT is an Alcanivorax DGAT.
10. The modified Cyanobacterium of claim 9 , wherein said Alcanivorax DGAT is an Alcanivorax borkumensis DGAT, or a biologically active fragment or variant thereof.
11. The modified Cyanobacterium of claim 10 , wherein said Alcanivorax borkumensis DGAT comprises a polypeptide sequence set forth in SEQ ID NO:15.
12. The modified Cyanobacterium of claim 1 , wherein said exogenous polynucleotide is present in an expression construct.
13. The modified Cyanobacterium of claim 12 , wherein said expression construct comprises a constitutive promoter.
14. The modified Cyanobacterium of claim 12 , wherein expression construct comprises an inducible promoter.
15. The modified Cyanobacterium of claim 1 , wherein said polynucleotide is codon-optimized for expression in a Cyanobacterium.
16. The modified Cyanobacterium of claim 1 , wherein said Cyanobacterium is selected from the group consisting of: S. elongatus PCC 7942, a salt tolerant variant of S. elongatus PCC 7942 , Synechococcus PCC 7002, and Synechocystis PCC 6803.
17. The modified Cyanobacterium of claim 16 , wherein said Cyanobacterium is a salt tolerant variant of S. elongatus PCC 7942.
18. The modified Cyanobacterium of claim 16 , wherein said Cyanobacterium is Synechocystis PCC 6803.
19. The modified Cyanobacterium of claim 1 , wherein said DGAT is a Acinetobacter baylii ADP1 diacylglycerol acyltransferase (AtfA), or a biologically active fragment or variant thereof, wherein said polynucleotide is codon-optimized for expression in Cyanobacteria, wherein expression of said DGAT is regulated by one or more inducible promoters, and wherein said Cyanobacterium is S. elongatus PCC7942 or a salt tolerant variant thereof.
20. A modified Cyanobacterium comprising an exogenous polynucleotide encoding a prokaryotic diacylglycerol acyltransferase (DGAT) that uses acyl-ACP as a substrate, wherein said modified Cyanobacterium produces a triglyceride, a wax ester or both.