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NAME: Aaron Holland

The overall goal of this project is to optimize lipid production of the algae Chlorella vulgaris in order to make it more viable as a fuel source. To do this, a glycerol kinase and transporter are being utilized in an effort to import glycerol molecules directly into the cell. We hypothesize that by importing glycerol into the cell, triacylglycerol (TAG) production will enhanced due to increased metabolic flux. , The application of the research lies in the fact that TAGs are an optimal feedstock for biodiesel. A previous experiment conducted in Kolling lab attempted to utilize this glycerol kinase/transporter by growing the cells into exponential phase and then performing a media exchange where the native medium is removed and replaced with nitrogen-deplete medium with 0.5% (w/v) glycerol. However, the lipid concentrations between the nitrogen-deplete cultures did not significantly vary from the nitrogen-deplete cultures with glycerol. This could be due to two main reasons: The first is that the algal cells did not have an adequate number of glycerol transporters in the cell membrane to have a measureable difference in lipid weight. The second is that the nitrogen deprivation, since it halts protein synthesis, interfered with the cell’s production of glycerol transporters. To test this, the cells will be grown in low concentrations of glycerol so that osmotic 6 pressure changes and potential toxicity are minimized. As the cells progress through the exponential and stationary phases, they will be dosed with even higher concentrations of glycerol. The purpose for the dosing of glycerol is to provide a chemical signal to the cells to upregulate the glycerol transporters on the cell membrane without lysing the cells. If the number of glycerol transporters can be increased, then glycerol flow into the cell will be increased, resulting in a higher level of TAG synthesis. Preliminary results have shown cell cultures that were dosed three times each with 0.10%, 0.50%, and 1.0% glycerol in lag phase, exponential phase, and stationary phase respectively, had 5% higher lipid accumulation than the control after 66 hours of growth. Performing this experiment again will allow us to see if that result can be repeated, if glycerol dosing is an effective way to increase glycerol transporter number, and if glycerol dosing will increase lipid accumulation.

 

To view their website click here: www.algalrenewablefuels.wordpress.com