After an unsuccessful experiment of trying to isolate Luminescent Bacteria from a squid, for experiment #2 I decided to collect the ink directly from a fresh squid specimen and isolate Luminescent Bacteria from this sample. I observed that bioluminescent bacteria live inside the squid ink sacs. These bacteria emit a constant glow, but the squid can control how much of that light escapes by changing the shape of the ink sac tissues. This is similar to an iris that lets more or less light into an eye. The squid ink sac also has a transparent layer across the surface that acts like a rudimentary lens, controlling the direction of the emitted light. By letting more or less light through from the bacteria, squid can match themselves to the brightness of the sea surface. This varies depending on how deep down they are and what time of day it is. Firstly, I dissected a squid to collect ink. I found the squid ink sac, which is located between the gills in the mantle cavity. Then, I pinched the opening of the sac (near the back of the funnel) with forceps while gently pulling up and cutting the connective membrane along its length. After cutting about 1/3 to 1/2 of it, I held the sac and pulled the sac off the liver, carefully removing the silvery-black ink sac.
After collecting
ink from a squid, I placed it into a petri dish. Then, I added 10 drops of 3% NaCl
solution on it and I put my petri dish in the incubator at 18 ºC for 24 hours.
You could try to add some nutrients to you growth medium in the petri dish. Maybe some bacterial LB broth (Sigma will sell this stuff as a powder you mix with water) and I think the culture recipes often include stuff like yeast extract, or something called bacto-peptone. In any event, you experiment shows that just because these bacteria grow inside of squid this doesn’t mean that they are easy to grow. Happy hunting, Jon Hayashi
ReplyDelete