Gélose Chapman

The gélose Chapman is the selective medium of the Bactérie S Halophile S and more particularly fermenting the Mannitol. Semi-synthetic medium.

Use

Insulation of the Staphylococcus

In the Anglo-Saxon countries, an alternative of this medium is called MSA (mannitol-salt-agar = gélose with the mannitol and salt).

Composition for the preparation of a Liter of medium.

pH = 7,4

111 G per liter of traditional Pressure-sealing medium.

an ordinary nutritive base.
a high percentage of NaCl which allows the selection of the halophilous bacteria (like the Staphylococcus ) and inhibits the great majority of the other bacteria.
a criterion of differentiation: the fermentation of the Mannitol revealed thanks to the turn of the indicator of pH: the Red phenol which allows an orientation towards certain species (like the species Staphylococcus aureus ).

Cultivate on this medium the Micrococcaceae and some others ( Bacillus , Enterococcus ) and even very seldom of the bacilli Gram-negative.

red Colonies: they are known as mannitol - because it do not ferment the mannitol, light alkalization of the medium by the use of Peptone S in their energy Métabolisme.
yellow Colonies: they are known as mannitol + because they ferment the mannitol in their energy metabolism with acidification of the medium.

In all the case, the micro-organisms cultivating on this medium highlighted their character Halophile.