MacConkey’s Broth Reaction in Coliform Count

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    • #1832
      cloudnine
      Participant

      in MPN count for coliform bacteria.
      i used double strength MacConkey’s broth.
      the positive reaction is the change in colour, purple to yellow and gas production.

      but some tubes turned to white.
      please reply why this white colour is formed?
      when these tubes are plated on MacConkey’s agar, they produced Non-lactose fermentor colonies, they are like Pseudo.

      yellow colour, because of lactose fermetation, acid produced reacts with the indicator and the colour changes.
      but i don’t know changing to white colour.
      MaC broth has only lactose as carbon source, i think.
      is there other that serves as carbon source, such as Peptone?

      best regards.

    • #29430
      Lukaszos
      Participant

      Do Bacterium which you are trying to confirme, come from the environment ??

      Best regards

      (Sorry for my English)

    • #57879
      Wrath_ing
      Participant

      Hi, can any suggest to me a suitable agar for doing plate count 4 coliform and e. coli? Thx

    • #58287
      jes
      Participant

      Try EMB agar (Eosine Methylene Blue). It’s selective for coliforms and gram-negative bacteria. here’s a link:

      http://www.jlindquist.net/generalmicro/dfemb.html

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