Protocol Online logo
Top : New Forum Archives (2009-): : Microbiology

Yellow E. coli colonies on MACCONKEY AGAR - (Apr/26/2009 )

helloooo

Does anyone having idea that E.coli culture can give slight yellowish colonies on Macckonkey agar . I havent seen such type of colonies in past. Presently I am trying to demonstrate purity of one of the E. coli culture. All other test like Indole test is showing E. coli , but on Macconkey few colonies are yellowish. Does anyone has idea about this. Your suggestions and observations are necessary to come out with conclusion.

Thanks

-somu-

"Few of the colonies"? So not all? You sure it's a pure culture?

-GeorgeWolff-

Our experience is that E.coli DH5α and NM522 cells are yellowish on MACCONKEY agar.

Regards,
T :)

-Tanja N-