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Streaking out yeast - (May/08/2008 )

Hi everybody.

I am having a huge problem in streaking out yeast cells onto agar media. I would like to streak my yeast cells onto YPD plates so that I have a few individuals colonies that I can select.

No matter what I do, whether I pick lots of cells or invisible amounts of cells, I only seem to get uniform fields of cells and not individuals colonies.

What is the secret to getting a nice streak?


Don't wait so long before checking your plates.


How do you streak your cells?


For getting single colonies, I use tooth picks for streaking, take a very low amount of cells from the plate and streak as follows:
divide the plate in about 8 triangles and start with streaking in the upper (left) corner of one triangle and streak downwards in zigzag lines. Go to the next triangle without taking new cells, streak again...
With bacteria I first suspend a little amount of culture in 1 mL water, take a new tooth pick, dip it once in the water and do the same as described above.
Sure you have yeast cells on your plate and not bacteria?
Good luck then wink.gif


Make sure your zig-zags are wide and many. If you just zig-zag 3 or 4 times it won't work well. Cover the entire triangle with the streak. I usually use inoculation loops for this, I find it easier than using toothpicks. But that's up to you