The standard way to streak a plate involves creating a resevoir of the sample you are studying, then using a sterile tool to streak through that at a steep angle. Then you streak through the first streak with another sterile tool, and so on and so forth.
As you streak through lines, the amount of bacteria pulled along is reduced until you are able to isolate individual colonies.
Pretty much. It’s like a little wire loop - sterilize it with a bunsen burner, let it cool, then take a swab from your source specimen and drag it into your agar for that section 1. Sterilize it again with the burner, cool, then drag through the last couple lines of 1 to get region 2. Repeat for 3 and again for 4. The sample size of individual microbes gets exponentially fewer each time - done correctly and region 4 is dotted with individual cells, which you leave alone for a while to incubate, then come back and start making your observations like how it’s interacting with the agar, what color, texture etc; smear it onto a microscope slide, see how it responds to different stains, it’s shape, it’s arrangement… then start checking all those findings against known properties of different microbes until you find a match.
Why do these agar plates always have two intersecting lines on one side and nothing on the other side? Is it like an environment control thing?
The standard way to streak a plate involves creating a resevoir of the sample you are studying, then using a sterile tool to streak through that at a steep angle. Then you streak through the first streak with another sterile tool, and so on and so forth.
As you streak through lines, the amount of bacteria pulled along is reduced until you are able to isolate individual colonies.
Til! Thanks!
Visual breakdown for anyone interested:
1 through to the end are all made with new, sterile… sticks?
Look ma, I’m a biochemist now!
Pretty much. It’s like a little wire loop - sterilize it with a bunsen burner, let it cool, then take a swab from your source specimen and drag it into your agar for that section 1. Sterilize it again with the burner, cool, then drag through the last couple lines of 1 to get region 2. Repeat for 3 and again for 4. The sample size of individual microbes gets exponentially fewer each time - done correctly and region 4 is dotted with individual cells, which you leave alone for a while to incubate, then come back and start making your observations like how it’s interacting with the agar, what color, texture etc; smear it onto a microscope slide, see how it responds to different stains, it’s shape, it’s arrangement… then start checking all those findings against known properties of different microbes until you find a match.