Chromogenic agar
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the permission of the Companies who produce
the products illustrated.
Chromogenic agar
Two chromogenic substrates
are combined in an agar to
distinguish micro-organisms
by their specific enzyme
activity
All images used in this file are reproduced with the permission of
the Companies who produce the products illustrated.
What is a chromogen
• A compound that can be converted to a
pigment
• This compound has a chromophore that is
colourless until the chromophore is
modified chemically.
• The chromophore is a functional group that
absorbs light giving rise to colour.
BioMerieux’s
selective
chromogenic
medium for
coliforms
and E.coli
COLI ID Chromogenic agar (by BioMerieux)
distinguishing coliforms from E. coli
Coliforms
E. coli
Merck’s
selective
chromogenic
medium for
coliforms
and E.coli
Coliforms and
E. coli have the
galactosidase
enzyme.
Only E. coli has
the
glucuronidase
enzyme
ChromocultTM chromogenic agar (by Merck)
distinguishing coliforms from E. coli
Coliforms
E. coli
SMID chromogenic agar (by
BioMerieux) for the detection of
Salmonella
Oxoid’s selective chromogenic medium for
Listeria spp. (blue colonies) and Listeria monocytogenes
(blue colonies and opaque halos)
Oxoid’s selective chromogenic medium for Enterobacter
sakazakii (blue-green colonies)