Bgal on plates

S L Forsburg forsburg at
Thu Feb 20 04:12:08 EST 1997

Martin Gossen wrote:

> >***Also, I recently saw a seminar that had slides of blue yeast
> >growing(?) on media.  Was the X-gal included in the media.  I thought
> >that B-gal wasn't excreted by yeast and that they had to be lysed,
> >what was going on here?
> It does work without lysis but the signals are much weaker (that's
> what Clontech say).

Oh yes, it works all right.  Many students have made PhD theses
out of screens conducted for mutants using beta-galactosidase 
reporters and colonies on plates. However, plate assays are less
sensitive;  you can't really recognize activity below about
2u (where units are determined by OD600).  That's what I 
recall, although my thesis was a long time ago.  :-)

Also, you can't just add XG to SD media;  the pH is all wrong.
You have to make up special plates.  They are quite stringent and
the cells arent very happy on them.  See the various works of
Guarente from the 80s for more info.

-- susan

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S L Forsburg          forsburg at
The Salk Institute
La Jolla, CA

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