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NAME: Ethan Adkins

The effects of polytheylene glycol versus glycerol on lipid production in Chlorella vulgaris

Lipid production in the mixotrophic microalga Chlorella vulgaris will be investigated by adding polyethylene glycol (PEG) to the growth medium and measuring lipid production versus biomass over time. It has been shown that adding glycerol to C. vulgaris causes an increase in lipid production (2). This could be caused by the extracellular glycerol bypassing glycolysis and being directly metabolized into triglycerides. However, it has also been shown that algae produce more lipids when under alcohol stress. This experiment will test this hypothesis by measuring lipid production when a similar alcohol to glycerol is used as a substrate. The current hypothesis is that PEG will increase lipid production and decrease biomass in C. vulgaris. These anticipated results would mirror the reproduced results of adding glycerol to CV medium (2), adding a 5:1 glycerol to glucose mixture to Chlorella protothecoides (6), as well as the results from adding PEG (400Da-4000Da) to Nannochloropsis oculata (4). C. protothecoides and N. occulata are two marine microalgae also being studied for possible use in biofuels. This experiment will test whether the increase in lipids was caused by substrate manipulation or by stress conditions brought on by glycerol. Possible problems with this experiment are contamination of cultures, however there have been no contaminations since problems with the autoclave were resolved.