studying the effect of different irradiances of light on the triacylglycerol yield in the marine...
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Studying the effect of different irradiances of light on the triacylglycerol yield in the marine diatom Thalassiosira pseudonanaMegan Snyder and Sam Huynh
Background InformationT. pseudonana is classified as
phytoplankton (photosynthesizing marine organisms)◦Diatom (microscopic, unicellular,
photosynthetic algae with a silica shell called a frustule)
Bacillariophyceae class (largest group of biomass producers)100,000+ species
High oil content (21-31%) by dry weightEntire genome is sequencedOil helps it float on the water to
photosynthesizehttp://www.diark.org/img/species_pict/Thalassiosira_pseudonana_CCMP1335
Oil from diatom is a potential alternative fuel
Oil composed of lipids◦Lipid: biological compound insoluble in water
but soluble in organic solventsTriacylglycerol (specific lipid) acts
primarily as energy storage in diatoms (three fatty acids attached to one glycerol)
Triaclyglcerol is a non-polar, or neutral lipid◦Polar lipids have a hydrophilic and a
hydrophobic end; neutrals do not. ◦Polar lipids located in cell walls
Triacylglycerol Transesterificationprocess to refine triacylglycerol; how does
it become biodiesel? Oil is purified and reacted with methanol or
ethanol in the presence of a catalyst (such as KOH potassium hydroxide or NaOH sodium hydroxide); the triacylglycerol is transformed to form esters and glycerol – remaining esters are biodiesel
Triacylglycerol Chemical Formula
Glycerol3 Fatty Acids
http://www.oliveoilsource.com/page/chemical-characteristics
Nile red (9-diethylamino-5H-benzo[α]phenoxazine-5-one) is a dye that collects in the neutral lipids of living cells◦Fluoresces under a certain wavelength,
then emits another wavelength◦The intensity of the fluorescence is
directly correlated to lipid content
Purpose: increase the triacylglycerol content in the diatom using different light irradiances
Importance: increased triacylglycerol yields per diatom can make the process of making bio-fuel from algae more efficient and economically feasible
Irradiance: measure of light that reaches the product surface
Why measure in irradiance and not intensity? Photosynthesis depends on the amount of light reaching the surface of the plant, not the intensity of the source
ProcedureDiatoms will grow a plastic container
under different irradiances of fluorescent light (test one irradiance at a time)◦Sides of the container will be covered with
aluminum foil to block out excess light◦In previous experiments, irradiances of
light have affected photosynthetic processes in T. pseudonana
◦Light on a 16 hour-on, 8 hour-off cycle, maintained by a light timer
Grown in f/2 agar, a solution that provides nutrients for marine algae
pH measured periodically with a Vernier probe to make sure CO2 levels stay constant
Container inside Styrofoam box with ice packs to keep temperature constant at about 53°F
Nile red stain will be applied to a few sample diatoms after six days
Data CollectionUse UV microscope equipped with a
camera◦Takes pictures of the cells fluorescing
Use Image J program to analyze level of fluorescence
http://accu-scope.net/3032_EPI_318CU.gif
http://www.chemistrytimes.com/Images/green_alga_with_nile_red.jpg
Inverted UV microscope
Green Algae stained with Nile red- Triacylglycerol fluoresces yellow-gold, phospholipids fluoresce red
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http://chemed.chem.wisc.edu/chempaths/GenChem-Textbook/Polar-Lipids-1019.html
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