Total Lipids

Yes you read the title correctly. Today’s lab post is about lipids (fats). More specifically what percent of the total biomass of algae I cultured is lipid? I have been culturing 6 one liter bottle of algae for about 5 weeks. I harvested them Monday and the total biomass was about 0.2000 g for one species, and 0.4000 g for the other species. It was a little disheartening to see the fruits (or I guess algae) of my labor centrifuged down to a tiny pellet of green in the tip of a 40 ml falcon tube, but this tiny green pellet has a lot to tell me about potential useful applications.

Precision syringe to extract hexane layer (containing hydrophobic compounds ie lipids, and pigments)

The cliff notes version , I disolved 30 mg of my algae in a solution and then add 1 ml of hexane. Anything that is hydrophobic will dissolve in the hexane, and I can remove it and then evaporate the hexane layer, and whatever is left in the 8ml vial is the lipids in my sample. One of my samples has 12% total lipids and the other has 16%.

One of my micro algal species is a potential candidate for biofuels, and the other is the richest natural source of the carotenoid β-carotene. Tomorrow I will do FAME to determine what fatty acids are in my samples, not just the total lipids and pigments.

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Comments
3 Responses to “Total Lipids”
  1. Sheryl says:

    Hello, I am wondering how you evaporated the hexane layer. Did you heat it? Thanks.

    -Sheryl

    • Mr. Chopp says:

      Sheryl,

      When I have the lipid in the hexane I dry the combined (total 3mL) hexane to complete evaporation under gentle stream of N2, weigh to within a 0.1 mg precision (5L/min for 30mins).

      Mr. Chopp

  2. Sheryl says:

    Wow thanks for your response. “Gentle stream of nitrogen” that made me laugh a little, because that’s a bit much for our research project. Is there a name to this process? My team is curious to know. I think we are just going to dry it in an oven instead. =)

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