Why single colony?

D.K. no.email at thanks.to.spam.net
Thu Mar 13 15:49:49 EST 2003

In article <3E707994.BB8FE01F at aon.at>, Philipp Wechner 
<mantis at aon.at> wrote:
>EdiSon schrieb:
>> After identifying the positive clones from the cell transformation
>> plates, why do we still need to streak and pick single colony for DNA
>> miniprep and protein? Don't all the decedents from that single
>> positive clone  have the same genetic made-up? What's the things we
>> try to avoid? Mutation in the cloned gene? Hetergeneous mixture of
>> plamids? What? Please be kind and blow up my super small brain. Thank
>> you for now! Cheers, EdiSon.

All these things, plus contaminants of all other kinds.

>You take single colonies because it is "good microbiological working".

Yes it is. 

>You are right - all cells should be the same.
>I often take a shovel full of colonies to inoculate my media for protein
>expression- this results in much faster growth. Never encountered any
>problems with my protein after this

Over the years, I've seen almost countless examples of screw-ups 
resulting from stubborn people doing thisngs like this. Examples
include: ending up working with wrong cells (!), loss of 
exression, loss of plasmid, accidentally selecting and working with 
a mutant. 

Do yourself and your PI a favour - always start with a single 


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