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Below, please find pictorial highlights of the research and its applications, as presented in peer-reviewed publications and at University, Conference, Government, and Industrial lecture settings.
Below, please find pictorial highlights of the research and its applications, as presented in peer-reviewed publications and at University, Conference, Government, and Industrial lecture settings.
Slides from Research Presentations
Slides from Research Presentations
Hydrogen production
Hydrogen production
A hydrogen-producing green microalgal culture with bubbles emanating toward the surface of the liquid medium
The Melis Lab achieved a breakthrough in this field, pioneering the so-called "sulfur deprivation" method for the sustained photosynthetic generation of hydrogen in green microalgae, upon alleviating the severe oxygen sensitivity of the process.
Hydrogen gas is drained through a syringe (inserted in the middle of the silicone stopper) and, through Teflon tubing, is collected in an inverted burette and measured by the method of water displacement. Photograph courtesy of Michael Barnes (Office of the President, University of California, Oakland).
Diffusion-based process for enhanced photosynthesis
Diffusion-based process for enhanced photosynthesis
A closed fed-batch bioreactor for diffusion-based CO2 uptake by photosynthetic microorganisms, enabling enhanced rates of photosynthesis and productivity
The Melis Lab applied, for the first time, a 100% CO2 gas stream to load the headspace of a gaseous/aqueous two-phase bioreactor. Efficient uptake and assimilation of headspace CO2 by the cells occurs spontaneously by diffusion and is concomitantly exchanged by photosynthetically produced O2.
Provision of 100% CO2 gas in the headspace of a microalga culture alleviates C-supply limitations in photosynthesis and results in enhanced productivity. (from Bentley and Melis 2011.)
Light-harvesting antenna engineering for enhanced photosynthesis
Light-harvesting antenna engineering for enhanced photosynthesis
A non-intuitive concept: minimizing the chlorophyll antenna aize of photosynthesis to maximize solar energy conversion efficiencies and productivities
(Left panel): A double whammy in photosynthesis and production. In a high-density wild type culture, fully pigmented cells at the surface over-absorb and wastefully dissipate bright sunlight (Energy Loss), whereas cells deeper in the culture are shaded and remain inert photosynthetically. This suboptimal configuration is known as The Light Saturation and Shading Effect, which is known to limit productivity. Reason for this pitfall is that maximum competition in the wild requires large chlorophyll antenna sizes to enable capturing more light for self, even if wasted, and preventing light capture by competing neighbors.
(Right panel): The Melis Lab pioneered the "Truncated Light-harvesting Antenna" (TLA) concept, whereby a genetically minimized pigment-protein light-harvesting antenna size of the photosystems prevents the over-absorption of incident sunlight and permits far greater sunlight penetration deeper into the culture, thereby enabling more cells in the medium to actively participate in photosynthesis, resulting in an enhanced culture productivity. This concept has been successfully reduced to practice in green microalgae, cyanobacteria, and diatom cultures, as well as in tobacco plants.
Synthetic Biology: Cyanobacteria as Cell Factories
Synthetic Biology: Cyanobacteria as Cell Factories
Photosynthetic generation of heterologous products
The Melis Lab has successfully installed and over-expressed in cyanobacteria exogenous genes from plants, bacteria, and humans, resulting in an enhanced generation of bioactive compounds (isoprenoid derivatives) and distinct biopharma proteins.
TTFC-Fusion constructs for protein over-expression
TTFC-Fusion constructs for protein over-expression
Folding models of the Tetanus Toxin Fragment C (TTFC), and modified heterohexameric (α,β*TTFC)3G1 phycocyanin disc
(Left panel) As a recombinant protein, when expressed by itself as a transgene in photosynthetic systems, the Tetanus Toxin Fragment C (TTFC), accumulates to very low levels, often below the detection limit, regardless of the promoter used. This low recombinant protein expression comprises a ubiquitous problem in all photosynthetic heterologous production systems.
(Right panel) The Melis Lab pioneered the concept of recombinant protein over-expression as a fusion with an abundant cellular protein, which is needed for survival and growth. In the example below, TTFC is fused to the β-subunit of phycocyanin, and it accumulates stoichiometrically with the latter as a functional component of an (α,β*TTFC)3 modified phycocyanin disc. Both phycocyanin and TTFC retain their respective catalytic functions in this fusion construct configuration.
FGF2-Fusion constructs for protein over-expression
FGF2-Fusion constructs for protein over-expression
Folding models of the bovine Fibroblast Growth Factor 2 (FGF2), and modified heterohexameric (α,β*FGF2)3G1 phycocyanin disc
(A) As a recombinant protein, when expressed by itself as a transgene in photosynthetic systems, the Fibroblast Growth Factor 2 (FGF2), accumulates to very low levels, often below the detection limit, regardless of the promoter used. This low recombinant protein expression comprises a ubiquitous problem in all photosynthetic heterologous production systems.
(B) The Melis Lab pioneered the concept of recombinant protein over-expression as a fusion with an abundant cellular protein, which is needed for survival and growth. In the example below, FGF2 is fused to the β-subunit of phycocyanin, and it accumulates stoichiometrically with the latter as a functional component of an (α,β*FGF2)3 modified phycocyanin disc. Both phycocyanin and FGF2 retain their respective catalytic functions in this fusion construct configuration.
Several other proteins and enzymes were shown to be over-expressed, in functional form, via this fusion constructs technology.
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