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Steven Baldassano

Preliminary Analysis of the Source and Destination of Carbon in Phaeodactlyum tricornutum under Nitrogen Deprivation. Steven Baldassano. AMOPs in Biofuels. AMOP = Aquatic Microbial Oxygenic Photoautotroph Includes cyanobacteria, algae, diatoms High neutral lipid yield (20-50% of dry weight)

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Steven Baldassano

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  1. Preliminary Analysis of the Source and Destination of Carbon in Phaeodactlyumtricornutumunder Nitrogen Deprivation Steven Baldassano

  2. AMOPs in Biofuels • AMOP = Aquatic Microbial Oxygenic Photoautotroph • Includes cyanobacteria, algae, diatoms • High neutral lipid yield (20-50% of dry weight) • Potentially more useful for biofuels than current sources such as corn grain ethanol • More efficient conversion of solar energy • Use of little or no land • Easier conversion of lipids to useful biofuels • Useful byproducts such as protein for animal feed

  3. Purpose • Determination of the effects of nitrogen deprivation on Phaeodactylum tricornutum • Inability to create proteins will change carbon composition • Measurement of carbohydrate/protein/lipid composition • Use of C13 labeling to determine source and distribution of carbon

  4. Experimental Setup Cultures of Phaeodactylum tricornutum grown for 4 days in F/2 media with sufficient N and C12 On day 4, cells were pelleted and resuspended in C13 labeled bicarbonate in sealed flasks 3 in F/2 media 3 in F/2 media without NO3- N2 bubbling used to evacuate flasks Assays performed on day 4 (t=0 timepoint) and day 7 (t=3 days after resuspension).

  5. Methods • pH • Cell count by microscopy • Optical density at 625 nm • Chlorophyll content • β-1,3-glucan (carbohydrate storage) • C13 content by mass spectroscopy • Membrane carbohydrates • Protein content • Lipid Content • Fractionation and C13 content using LCMS • Ash weight percent

  6. Results • N- cells became much larger and more ovoid • Significantly lower cell count in N- samples due to arrested cell division • Decreased chlorophyll content in N- samples • Decrease in pH relative to N+ samples • Optical density readings correlate well with cell count and dry weight for N+ samples only

  7. Results N-, ash-free dry weight % N+, ash-free dry weight %

  8. Results • Overall lipid increase after resuspension:

  9. Ongoing Research • Completion of lipid content analysis • Fractionation • C13 labeling • Mass spectroscopy for carbohydrate C13 content • C13 content will provide information as to the source of carbon for glucan and lipid increase • rearrangement vs de novo synthesis

  10. Summary • Nitrogen deprivation resulted in changes in composition • Increase in cell size and mass • Increase in glucan content • Increase in lipid content (per cell and dry weight) • Slight decrease in overall lipids per ml • Decrease in membrane carbohydrate content • Decrease in protein content • Source of carbon for lipid and glucan increase to be determined soon

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