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Bubbles in my agar plates after drying


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#1 planktonica

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Posted 11 March 2009 - 10:03 AM

As some of you know, I've been having cloning problems (solved, thanks to all your kind help). But that seems to be kind of "common"... say, cloning is not always as straight forward as we wish.

But now my plates have tiny bubbles right at the bottom, not on top, of the agar plate. The strange thing is that the bubbles are NOT there when I take the plates out of the 4C storage to the dryer. I dry the plates and BOOM! there they are! I thought I was drying too much, so I shorten the time to several different times (and anyway, I've been preparing and drying plates my entire grad school program (almos about to finish... if the poltergeist wants me to) and never had that problem before. Now, out of the blue, the bubbles appear after a short time, say 10-15 min of drying. I hope the bubbles are not hindering my colony growth, however, I don't know.

Anyone with an idea of why this is happening?? is this the pre-graduation curse going on?

Thanks for your help

#2 HomeBrew

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Posted 11 March 2009 - 12:09 PM

The solubility of gases decreases with increasing temperature, so (obviously) something is outgassing from the agar plates as they warm. Where did the gas come from? I have no good ideas -- maybe you swirled the media too vigorously before pouring and/or cooled the plates too rapidly?

#3 lab rat

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Posted 11 March 2009 - 01:07 PM

The solubility of gases decreases with increasing temperature, so (obviously) something is outgassing from the agar plates as they warm. Where did the gas come from? I have no good ideas -- maybe you swirled the media too vigorously before pouring and/or cooled the plates too rapidly?


Could you have some bacterial contamination? I had this problem a few times, and my prof suggested that a bug may have been in the laminar and gotten into my plates as I poured them. (I was using amp, too!) The plates nearest the outside edge of the hood seemed to get the bubbles. I switched to a different hood, made sure my gloves were clean before I poured my next batch of plates, and didn't pour plates so close to the edge of the hood and the problem went away.
42..."An immutable fixed-precision number of unlimited magnitude." <a href="http://en.wikipedia....amming_language)" target="_blank">http://en.wikipedia....amming_language)</a>, accessed 25June2009.

#4 HomeBrew

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Posted 11 March 2009 - 06:19 PM

I thought about contamination possibly causing the bubbles, too -- sort of like Swiss cheese -- but planktonica says the bubbles were not there when the plates were taken from the refrigerator, and only became apparent after warming for 10-15 minutes. I can't see bacteria rousing and growing enough to evolve that much gas in so short a time...

#5 blue800

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Posted 11 March 2009 - 08:51 PM

I've had the same problem sometimes it happens sometimes it doesn't. The bubbles go away when the plates go back to 4 degrees. It does not affect the bugs. I'm pretty sure its not contamination. I'm also pretty sure it's not due to "rapid cooling" as I tend to stack my hot plates which causes much slower cooling. Otherwise I can't explain it. Nor can anybody I show them to.

#6 microgirl

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Posted 12 March 2009 - 10:18 AM

This occasionally happens in our lab too - just the attack of the lab gremlins! It's totally annoying when your looking for that one colony on your transformation plate in among the hundreds of tiny bubbles.

As some of you know, I've been having cloning problems (solved, thanks to all your kind help). But that seems to be kind of "common"... say, cloning is not always as straight forward as we wish.

But now my plates have tiny bubbles right at the bottom, not on top, of the agar plate. The strange thing is that the bubbles are NOT there when I take the plates out of the 4C storage to the dryer. I dry the plates and BOOM! there they are! I thought I was drying too much, so I shorten the time to several different times (and anyway, I've been preparing and drying plates my entire grad school program (almos about to finish... if the poltergeist wants me to) and never had that problem before. Now, out of the blue, the bubbles appear after a short time, say 10-15 min of drying. I hope the bubbles are not hindering my colony growth, however, I don't know.

Anyone with an idea of why this is happening?? is this the pre-graduation curse going on?

Thanks for your help



#7 HomeBrew

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Posted 12 March 2009 - 06:17 PM

If it's that sporadic, perhaps it's an occasional lot of defective petri dishes...

#8 planktonica

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Posted 13 March 2009 - 08:00 AM

Thanks everyone!
I think that Homebrew is right with the swirling too vigorously theory. I only got that from antibiotic containing plates, never from non antibiotic plates. I usually cool down the agar at 55C for at least 2 hours before pouring. If I have no antibiotics I just pour the plates with no swirling to mix, the opposite for my spc plates. I usually have a magnet bar autoclaved inside the agar, but probably I am swirling too fast.




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