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why do some colonies keep growing in the chiller?

contamination competent cells

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7 replies to this topic

#1 Curtis

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Posted 25 September 2012 - 02:32 AM

On some of my plates the colonies keep growing even in the chiller. Usually after 2-3 days the whole plate is full. The plates smell really bad. First I thought it is because of degraded ampicilin, but then I noticed this is only happening to the plates that have colonies of transformed chemically competent cells. The plates that have colonies of transformed electroporation competent cells don't have this problem. Why is that? Is this because of bacilli contamination?

#2 Inbox

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Posted 25 September 2012 - 03:39 AM

How your colonies look like? are they normal morphology? if not they may be contamination. are your bacteria motile? motile bacteria may be moving on plate. Did you check whether they are transformed or not by growing on LB+amp?

#3 Curtis

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Posted 25 September 2012 - 09:55 PM

yes I tried, all of'em are transformed. They look normal after 16 hrs of incubation at 37C, but when I put them in the chiller they still keep growing.

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Posted 25 September 2012 - 10:39 PM

For bacteria optimal temperature for growth is 37 C. But normally is range of temperature they grow, even at cold also. Abt electroporated and transformed growth differences, hard to tell.

#5 phage434

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Posted 27 September 2012 - 02:51 PM

I'd suggest your competent cells stock is contaminated with some other species, likely a mold, or a tap water bacterium. Many are resistant to amp. Are these homemade competent cells?

#6 Curtis

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Posted 28 September 2012 - 02:08 AM

Yes, my student makes them in the lab.

#7 El Crazy Xabi

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Posted 01 October 2012 - 11:20 PM

Related old thread:
http://www.protocol-...osts/17044.html

#8 Curtis

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Posted 02 October 2012 - 02:52 AM

yes I have read this before. I'm really puzzled what's going on.





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