Team:Wash U/Project
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Our project goal is to maximize the photosynthetic productivity for a series of photobioreactors containing ''Rhodobacter sphaeroides'' under both high and low light intensities by synthetically regulating the size of the light-harvesting antenna complex LH2. We chose to undertake such a project in ''R. sphaeroides'' due to its well-characterized photosynthetic and genetic system. | Our project goal is to maximize the photosynthetic productivity for a series of photobioreactors containing ''Rhodobacter sphaeroides'' under both high and low light intensities by synthetically regulating the size of the light-harvesting antenna complex LH2. We chose to undertake such a project in ''R. sphaeroides'' due to its well-characterized photosynthetic and genetic system. | ||
- | The antenna system functions to expand the spectrum of light available for photosynthesis by absorbing different wavelengths than that of the reaction center. Essentially, it is like the dish around the main receiver of any antenna. Marine bacteria, such as ''R. sphaeroides'', evolved very large antenna complexes to absorb light in a natural environment where there is great competition for photons. As a result, the photosynthetic machinery is saturated at low light intensities in a synthetic non-competitive environment, such as a bioreactor. This causes up to 95% of incidental photons to be dissipated as heat or fluorescence by bacteria through a process called Non-Photochemical Quenching (NPQ) (Mussgnug et al., 2007). In essence, these photons are being wasted as NPQ reduces light penetration into and across bioreactors and starves the shaded cells for for photons. One method that has been shown to improve photosynthetic efficiency is the reduction of light-harvesting antenna sizes (Polle et al., 2002, Mussgnug et al., 2007). Though, current approaches to this end are difficult to precisely control from the perspective of biological engineering and synthetic biology | + | The antenna system functions to expand the spectrum of light available for photosynthesis by absorbing different wavelengths than that of the reaction center. Essentially, it is like the dish around the main receiver of any antenna. Marine bacteria, such as ''R. sphaeroides'', evolved very large antenna complexes to absorb light in a natural environment where there is great competition for photons. As a result, the photosynthetic machinery is saturated at low light intensities in a synthetic non-competitive environment, such as a bioreactor. This causes up to 95% of incidental photons to be dissipated as heat or fluorescence by bacteria through a process called Non-Photochemical Quenching (NPQ) (Mussgnug et al., 2007). In essence, these photons are being wasted as NPQ reduces light penetration into and across bioreactors and starves the shaded cells for for photons. One method that has been shown to improve photosynthetic efficiency is the reduction of light-harvesting antenna sizes (Polle et al., 2002, Mussgnug et al., 2007). Though, current approaches to this end are difficult to precisely control from the perspective of biological engineering and synthetic biology. |
- | Our synthetic regulation | + | Our intention is to create a more dynamic system to vary antenna size that is dependent on incident light intensity and that can be readily optimized using bioengineering principles. This synthetic regulation of the LH2 complex should result in the bacteria grown under high light intensities expressing fewer LH2 complexes than the cells that are more shaded, leading to a reduction of wasted incident photons while maintaining a high overall absorbance across subsequent bioreactors. Consequently, we expect to see an increase in the total photosynthetic productivity for our mutant ''Rhodobacter sphaeroides'' when compared to the wild type grown under similar conditions. |
Revision as of 23:25, 15 October 2009