Modified photosynthetic microorganisms for producing lipids

Inventors

Roberts, James • Cross, Fred • Warrener, Paul • Munoz, Ernesto Javier • Hickman, Jason W.

Assignees

Lumen Bioscience Inc

Abstract

This disclosure describes genetically modified photosynthetic microorganisms, e.g., Cyanobacteria, that contain one or more exogenous genes encoding a phospholipase and/or thioesterase, which are capable of producing an increased amount of lipids and/or fatty acids. This disclosure also describes genetically modified photosynthetic microorganisms that contain one or more exogenous genes encoding a diacyglycerol acyltransferase, a phosphatidate phosphatase, and/or an acetyl-CoA carboxylase, which are capable of producing increased amounts of fatty acids and/or synthesizing triglycerides, as well as photosynthetic microorganism comprising mutations or deletions in a glycogen biosynthesis or storage pathway, which accumulate a reduced amount of glycogen under reduced nitrogen conditions as compared to a wild type photosynthetic microorganism.

Core Innovation

The invention provides genetically modified photosynthetic microorganisms, specifically Cyanobacteria, that contain one or more exogenous genes encoding lipases such as phospholipases, lysophospholipases, or thioesterases, or functional fragments or variants thereof. These modifications enable the microorganisms to produce increased amounts of lipids and/or fatty acids compared to their wild-type counterparts. Additionally, some modified microorganisms include exogenous genes encoding enzymes involved in triglyceride biosynthesis, such as diacylglycerol acyltransferase (DGAT), phosphatidate phosphatase, or acetyl-CoA carboxylase, further increasing the production of fatty acids and triglycerides.

A major problem addressed is that Cyanobacteria and similar photosynthetic microorganisms naturally produce limited amounts of oil and do not generate triglyceride energy storage molecules, as they typically lack the key enzymes required for triglyceride synthesis. Instead, these organisms accumulate glycogen as their primary carbon storage molecule. Existing photosynthetic organisms like algae are difficult to genetically manipulate and tend to have lower oil production under culture conditions than in the wild.

To overcome this problem, the invention discloses strategies such as introducing polynucleotides encoding specific lipases into photosynthetic microorganisms, optimizing expression using various promoters, and combining lipase expression with further genetic modifications. These may include introducing genes for triglyceride synthesis enzymes and creating mutations or deletions in glycogen biosynthesis or storage pathway genes, resulting in strains with reduced glycogen accumulation and enhanced lipid and fatty acid content under both normal and stress conditions, such as nitrogen limitation.

Claims Coverage

The independent claim focuses on two main inventive features involving genetically modified Cyanobacteria for enhanced fatty acid production.

The claims are directed to genetically engineering Cyanobacteria with both an acyl-ACP thioesterase and impaired glycogen biosynthesis, resulting in enhanced fatty acid production beyond what is achieved by thioesterase expression alone.

Stated Advantages

Documented Applications