Green and Brown-Luke

Week 2, Part 1: Horseshoe Crab

Horseshoe crab blood has a protein in it that detects and coagulates upon contact with lipopolysaccharide producing bacteria. Because of the density of gram negative bacteria in the horseshoe crabs habitat, they are constantly at risk of infection. The natural solution for the survival of horseshoe crabs was to evolve blood that immediately attacks the bacteria. This allows the crabs to fight infection splendidly and have one of the most interesting immune systems of any animal. Limulus amebocyte lysate, the protein that attacks bacteria, is present in the blood of horseshoe crabs and can be extracted for medical purposes. The blood and more specifically the protein have been used to detect harmful pathogens in pharmaceuticals for years. Any injection you are given, whether it’s a flu shot or an IV drip has most likely been tested for sterility using limulus amebocyte lysate.

Lipopolysaccharides or LPS for short is a chemical that is located in the outer cell membrane of many bacteria. Gram negative bacteria, the main category of bacteria that contain LPS in their cell wall, include things like E. coli.

So what are my lab partner and I doing with a baby pool full of saltwater with a large adult female horseshoe crab in it? We are using her blood to test for toxins in our algae cultures. The same chemical that make some bacteria deadly (LPS) may exist in the microalgae that we intend to turn into food. In order to assess this and identify harmful cultures, we plan to drain some of her blood and centrifuge it to extract the protein for tests.

Week 2, Part 2:

I recently examined our Nannochloropsis cultures under a microscope. The purpose was to check for purity and to make sure there is nothing extra like amoebas among the tiny cells. Fortunately, everything was uniformly green and round. I even observed a few cells undergoing mitosis and dividing. Though this is a good sign, if the cultures grow too much and the water becomes over crowded the cultures could crash, or in other words they could all die at once. The same could happen if a foreign bacteria or algae got into the water: the water would turn from a rich, healthy greet to a sick opaque yellow that indicates the death of the whole batch. This is why constant examination with microscopes, as well as frequent shifts into larger containers is important. As the cultures keep growing they need larger containers to accommodate their population. They are currently in two 2 liter flasks and even still the water is getting so densely saturated with algae that there is sediment at the bottom of the flasks. Soon, we will be concentrating batches of algae for testing, nutritional analysis, and much more.

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