detect secretions on plates

Alistair Forrest forrest at
Sat May 28 07:07:11 EST 1994

marvin at (Nivram) writes:

>can anyone tell me if there is a way to detect proteins secreted by 
>bacterial colonies growing on agar without killing the colonies ? i am 
>looking for ways which do not use radioactive labelling, antibodies 
>precipitation etc... just simple ones.  Is there an indicator which 
>changes colour when it comes in contact with proteins ?


It depends what proteins you're trying to detect. If they're enzymes you can 
include, enzymatic substrates that produce coloured products. If you were using
an indicator that reacted to any protein, surely all colonies would light up
anyway. It would just depend whether they are secreting into the media.
If you were looking for a specific protein, then you could do a colony blot and
screen with antibody and HRPO.

You could also make a duplicate plate and then stain the plate with some sort of
protein stain, such as coomassie (I think it'll work in agar?).

Sorry if this hasn't helped (try a posting to molbio.proteins if you haven't already)

Alistair Forrest (PhD student CSIRO-Australia)

More information about the Proteins mailing list