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now: Sat Jun 25 10:07:06 2022 ... mod: Mon Mar 29 07:39:56 2021
Streak for Isolation
From a culture of mixed or concentrated bacteria, dilute the sample by streaking on an agar plate so that colonies arising from individual cells can be isolated.
- sterilize a bacterial loop by flaming
- allow the loop to cool slightly and gather a small sample of either bacterial culture or a small scraping of a frozen bacterial stock onto the loop
- for frozen stocks, do not allow the stock to thaw
- streak the loop across the top of a bacterial agar plate in three parallel lines
- the lines should be fairly close together
- streak using the wide part of the loop, not the edge of the loop
- flame sterilize the loop and cool by stabbing a clean part of the agar plate
- make three new parallel streaks starting by going across the last part of the previous three streaks and continuing onto a clean part of the plate
- repeat the last two steps three or four times being careful to only contact the immediately previous streaks and not earlier streaks
- grow at 37C overnight
- there are many procedures that will work, but this procedure is quick, easy to perform and more reliable than most others