Why do my yeast plates end up looking like this? enter image description here

And not this?

enter image description here

My yeast plate is composed of wort + agar.

1 Answer 1


It looks like you streaked several times from the same sample of yeast, and that there was a bit too much liquid in each streak (they resemble puddles). The liquid should be nearly invisible on your when applied to the plate. Also the plate surface should be a bit dry, so liquid is absorbed quickly.

The streaking technique is important too: the plate in the second picture was streak at least twice, but yeast was only added once. They dipped the inoculating loop in the yeast sample for the streak on the left, then the loop was sterilized and used for the second streak on the right - without adding any more yeast. The yeast in the right streak came from the streak on the left.

Many people will repeat the steak & sterilize steps 4 or 5 times as they work around the plate, spread the yeast thinner and thinner. I also suspect that the first streak plate in second picture was streaked over again, to get the single cell colonies between the heavy streaks.

This page from the Maltose Falcons provides a lot more detail.

  • Thank you very much. I am going to give your advice a shot in a second. I watched a vid online as well stating what you said. I did indeed keep dipping back into the same sample of yeast streaking new lines each time. I didn't streak from streaks I had already made.
    – fthinker
    Commented Aug 22, 2015 at 3:43
  • I can say your advice worked out quite nicely.
    – fthinker
    Commented Sep 8, 2015 at 1:32

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