Microorganisms with broadened light absorption capability and increased photosynthetic activity
Inventors
Roberts, James • DOUGHTY, David M.
Assignees
Lumen Bioscience Inc • Reliance Holding USA Inc
Publication Number
US-10787488-B2
Publication Date
2020-09-29
Expiration Date
2036-07-07
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Abstract
Photosynthetic microorganisms with broadened light absorption capability and increased photosynthetic activity are described. Broadened light absorption is achieved by modifying the microorganism to utilize non-native bilins. Increased photosynthetic activity results from the broadened light absorption and can also result from a decrease in self-shading. The microorganisms include Cyanobacteria, including modified Cyanobacteria.
Core Innovation
The invention provides modified photosynthetic microorganisms, including Cyanobacteria, that have broadened light absorption capability and increased photosynthetic activity. This is achieved by engineering the microorganisms to utilize additional, non-native bilin pigments, enabling them to absorb and use portions of the visible light spectrum that are inaccessible to their native forms.
The broadened light absorption results from modifications such as the insertion of exogenous nucleotide sequences encoding enzymes and proteins (including PebA, PebB, RpcG, and CpeS) involved in the biosynthesis and utilization of new bilins, such as phycoerythrobilin (PEB) and phycourobilin (PUB). Deletion or down-regulation of native genes, such as CpcE, can further enable the effective incorporation of non-native bilins by reducing competition with native pathways.
This innovation addresses the problem that natural photosynthetic microorganisms typically utilize only a limited range of bilins, making them specialists for a narrow light spectrum and limiting photosynthetic efficiency and biomass production, especially under suboptimal light conditions or high cell densities due to self-shading. By expanding the active photosynthetic spectrum and potentially decreasing self-shading, the modified microorganisms display increased photosynthetic activity and growth.
Claims Coverage
The patent claims center on a modified Cyanobacterium with broadened light absorption and increased photosynthetic activity, covering three main inventive features related to genetic modifications affecting bilin synthesis and utilization.
Genetic modification for non-native bilin biosynthesis and utilization
A modified Cyanobacterium is created through (i) insertion of one or more exogenous nucleotide sequences encoding PebA, PebB, RpcG, and CpeS, and (ii) deletion of an endogenous nucleotide sequence encoding CpcE. This genetic modification enables the microorganism to utilize non-native bilins, specifically allowing for the production and functional incorporation of PEB and PUB, resulting in increased photosynthetic activity compared to the wild type.
Broadened light absorption and increased photosynthetic activity
The modification results in a Cyanobacterium capable of utilizing a functioning non-native PEB and PUB, which broadens the spectrum of absorbed light and increases photosynthetic activity. The functional outcomes include production of phycocyanin with red and purple pigments and increased oxygen evolution under a wider range of light wavelengths.
Method to enhance photosynthetic performance via gene insertion and deletion
A method is provided to increase photosynthetic activity in a Cyanobacteria by inserting one or more exogenous nucleotide sequences encoding PebA, PebB, RpcG, and CpeS and deleting an endogenous nucleotide sequence encoding CpcE. This approach enhances photosynthetic activity by enabling absorption of additional light wavelengths and/or reducing self-shading effects.
In summary, the inventive features cover genetic modifications that enable Cyanobacteria to utilize non-native bilins for broadened light absorption and enhanced photosynthetic activity, methods for achieving these modifications, and the resulting improved physiological properties.
Stated Advantages
Modified microorganisms exhibit broadened light absorption capability, enabling more efficient use of the visible light spectrum for photosynthesis.
Increased photosynthetic activity is achieved, which can lead to enhanced total carbon fixation, greater production of carbon-containing compounds, and increased biomass accumulation.
Reduction in self-shading within cultures improves light penetration and overall growth efficiency.
Functional expression of non-native bilins allows photosynthetic microorganisms to display enhanced oxygen evolution in response to specific light wavelengths (e.g., green and blue light).
Production of phycocyanin with novel red and purple pigments, offering additional value as pigments.
Documented Applications
Cultivating modified photosynthetic microorganisms for increased biomass production to be used for energy, fuel, chemicals, and food.
Production of bioethanol, biodiesel oil, and biojetfuel from enhanced microbial biomass.
Processing of environmental carbon dioxide through improved photosynthetic activity.
Generation of phycocyanin pigments with novel colors (red and purple), valuable for natural pigment applications.
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