Send to

Choose Destination
Res Microbiol. 1993 May;144(4):285-93.

Mutations in phoB, the positive gene activator of the pho regulon in Escherichia coli, affect the carbohydrate phenotype on MacConkey indicator plates.

Author information

Department of Biology, University of Konstanz, Germany.


Mutants defective in phoB, the positive gene activator of the Escherichia coli pho regulon, exhibit aberrant behaviour on MacConkey indicator plates. They appear pale in the presence of a fermentable carbon source such as trehalose, maltose or glucose. The addition of at least 5 mM phosphate corrects this defect. Colonies of phoB+ strains turn red on MacConkey indicator plates and derepress the pho regulon when the cells are able to ferment the carbon source. In contrast, the inability to ferment the carbon source maintains the pho regulon in the repressed state.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center