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I recently started growing some Geotrichum Candidum (GC) on Sabouraud dextrose agar (SDA) beds. The SDA was poured into sterilized petri dishes. After setting the plates in a cooler (20 C) for a day, I then inoculated the plates with a tiny smidge of GC. The GC is growing happily in that environment.

However, today on day 3, I noticed a crack across the SDA like shown in the picture below.

What does this mean? Did I prepare the plate wrong? Or is my GC just a bit naughty and somehow burrowing into the SDA?

Please note I am not a trained biologist, I've learned the skills I require for my activity from online resources and advice.

a crack in sabouraud

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    $\begingroup$ It could just be the agar drying out. $\endgroup$
    – canadianer
    Jul 21 at 0:20
  • $\begingroup$ My initial thought. The cooler is at 80 % relative humidity though. Isn't that enough? $\endgroup$ Jul 21 at 0:45
  • $\begingroup$ I suppose evaporation can occur at any relative humidity less than 100%. Is the agar shrinking in terms of thickness and/or peeling away from the side of the plate? These are also signs of desiccation. $\endgroup$
    – canadianer
    Jul 21 at 0:59
  • $\begingroup$ I see no signs of desiccation on the surface nor on the edges of the agar. $\endgroup$ Jul 21 at 1:04
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    $\begingroup$ @neydroydrec If that turns out to solve your problem, can you please add it as an answer to your own question? Then it will help the next person with a mysterious crack in their agar. $\endgroup$
    – jakebeal
    Jul 22 at 1:25

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