Streak plating that is X3

Today I had the most fun and interesting lab ever in Microbiology! We got to use two different techniques for culture isolation.

The streak plate method where you use a sterilized loop to spread a bit of a mixed culture onto a petri dish's layer of nutrient agar. Then after successive sterilizations of the loop and spreading from the last area onto a new part of the agar the goal is to get the bacteria isolated on their lonesome so when they multiply into little colonies it is a pure culture. Meaning just one kind of microorganism.

The second one we did was the pour plate method where it uses dilution to isolate the bacteria. You have the test tube of mixed culture then three tubes of the nutrient agar heated so it is not yet solid. You use the loop to transfer just a bit of the mixed culture from its test tube to tube #1. Then you swish it to mix and sterilize the loop. You repeat the process dipping from tube #1 to tube #2, sterilize loop, then dip twice from tube #2 to tube #3. Then you pour each tube of nutrient agar into a petri dish and see how they grow. Typically the #1 dish is unusable because there are so many microorganisms in it.

And the one I'm looking forward MOST to seeing next week is the special little dish we did at the end which is used to get bacteria from the environment. When you pour it you get the nutrient agar a little over the lip (like water it has surface tension so you can do this) and once it solidifies you can go touch it to something and see what grows. One person in my class touched a door handle, one person a computer mouse, I know one person went into the bathroom. Me? I licked it. Despite having beef bouillon and smelling a bit like beef broth it just tasted like gel, like unflavored chap stick.

So yeah! I can't wait to go back next week and see how everything's grown! Also next week's lab has us making our own slides and staining them for viewing under a microscope! GLEE!