Cyanobacteria having improved photosynthetic activity
Inventors
Roberts, James • Carleton, Michael • CARRIERI, Damian • Hickman, Jason W.
Assignees
Publication Number
US-11279912-B2
Publication Date
2022-03-22
Expiration Date
2034-03-10
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Abstract
This disclosure describes modified photosynthetic microorganisms, including Cyanobacteria, that have a reduced amount of a light harvesting protein (LHP) and contain one or more introduced or overexpressed polynucleotides encoding one or more enzymes associated with lipid biosynthesis, and which are capable of producing increased amounts of fatty acids and/or synthesizing triglycerides.
Core Innovation
The invention concerns modified photosynthetic microorganisms, particularly Cyanobacteria, which possess genetic modifications that lower the amount of light harvesting protein (LHP) by increasing the expression of NbIA gene or by introducing an exogenous NbIA gene or promoter. These modifications lead to an increased NbIA polypeptide level, resulting in enhanced photosynthetic activity and a reduced amount of LHP compared to wild-type organisms.
Unlike algae, which are difficult to genetically manipulate and exhibit reduced oil production in culture, Cyanobacteria can be readily genetically engineered. The problem addressed is the saturation of the light-harvesting capacity of LHPs, which does not allow further enhancement in photosynthesis under higher light intensities. By modulating LHP levels in Cyanobacteria, this invention enables improved photosynthetic efficiencies and increased growth rates.
Additionally, the invention includes Cyanobacteria modified with the introduction of nucleic acid sequences encoding exogenous polypeptides, which may include enzymes for lipid biosynthesis or therapeutic polypeptides. These modifications enable the production of increased fatty acids, triglycerides, or other valuable carbon-containing compounds. Methods for achieving these modifications include adding or overexpressing NbIA genes or promoters and introducing exogenous genes, resulting in cultures with enhanced photosynthetic activity and bioproduct generation.
Claims Coverage
The claims center on two main inventive features relating to genetically modified Cyanobacteria and cell cultures comprising these organisms with specific enhancements.
Genetic modification of Cyanobacteria to overexpress NbIA and reduce LHP, resulting in enhanced photosynthetic activity
This inventive feature covers a cell culture of modified Cyanobacteria that includes: - Genetic modifications comprising addition of an endogenous NbIA gene, exogenous NbIA gene, or addition of a promoter that regulates NbIA gene expression. - The modifications cause, as compared to wild-type Cyanobacteria: - Increased level of NbIA polypeptide or a biologically active fragment including a conserved domain, - Enhanced level of photosynthetic activity, - Reduced amount of light harvesting protein (LHP). The claim further specifies that a nucleic acid sequence encoding an additional exogenous polypeptide is added.
Expression of exogenous polypeptides, such as therapeutic polypeptides, in Cyanobacteria under specific light conditions
This inventive feature covers: - Cyanobacteria cell cultures as above, cultured at light intensities between about 200 and 2000 micromol photons per square meter per second, - Where the genetically modified Cyanobacteria express the exogenous polypeptide introduced by the nucleic acid sequence, - The exogenous polypeptide may be a therapeutic polypeptide as further defined in dependent claims.
In summary, the inventive features cover Cyanobacteria genetically engineered to overexpress NbIA resulting in reduced LHP and enhanced photosynthetic activity, and the introduction and expression of exogenous polypeptides, including therapeutic ones, especially under specified light conditions.
Stated Advantages
The modified Cyanobacteria demonstrate an increased level of photosynthetic activity compared to wild-type, resulting in enhanced growth, division rates, and biomass accumulation.
Introduction of genetic modifications enables the production of increased amounts of fatty acids and/or synthesis of triglycerides for use in biofuel or specialty chemical production.
Reduction of light harvesting proteins by modulating NbIA expression leads to Cyanobacteria cultures with improved efficiency for converting light to chemical energy under higher light intensities.
Documented Applications
Production of biofuels such as biodiesel by generating and harvesting increased fatty acids and triglycerides from modified Cyanobacteria.
Use of modified Cyanobacteria as feedstock for manufacturing various specialty chemicals.
Expression of exogenous polypeptides, including therapeutic polypeptides, in Cyanobacteria cultures for potential pharmaceutical production.
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