We were having a problem with our experiment (culturing microbes on homemade nutri agar) so we decided to change our set-up. It already cost us quite some money. So, we saw this procedure. Can anyone tell if this is legit? Thank you!

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  • 1
    $\begingroup$ You have more chance of a useful answer if you include brief outline of your original protocol and your problems. $\endgroup$
    – Michael_A
    Sep 16, 2017 at 4:31
  • $\begingroup$ 1. What kind of bacteria are you using? 2. I prefer to store my Petri dishes at room temperature. If they are contaminated at least I can see it. If contaminated Petri dishes are stored in the fridge, you'll see the contaminant only after inoculating your strain $\endgroup$
    – Flo
    Sep 20, 2017 at 9:48
  • $\begingroup$ Replace "microbes" with "bacteria." $\endgroup$
    – user37894
    Dec 20, 2017 at 7:51

1 Answer 1


It would be great if you could provide more information with regards to what you have done already and what the problems were that you observed. That being said, yes, the "protocol" you found should work.

I am assuming that this is some kind of homework / school project so you don't actually need to know what organisms you are inoculating with and at what levels.

One thing I would recommend is that when you take your swab sample, wet your swab by dipping it into the sterilised water first and then swab a predefined area of about 10cm x 10cm (4in x 4in) very thoroughly before putting the swab back into the test tube. Once back in the test tubes make sure that you swirl the swab around for a sufficient length of time (~30s) and press the swab against the inside of the test tube to allow as much liquid as possible to run out of the swab. The last step is important in order to maximise the yield of bacteria, yeasts and moulds that you might find in your sample.


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