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Biology LibreTexts

2.4: Review Questions

  • Page ID
    15961
  • 1. Based on your results and the information in the lab manual, fill in the table below.

    Predicted Gram Reaction Ability to ferment lactose/sucrose Ability to ferment mannitol Coliform or Non-coliform
    S. aureus
    E. coli
    P. aeruginosa
    M. luteus

    2. What general type of growth medium would you use to:

    (a) grow one type of bacteria but inhibit the growth of another type?

    (b) discriminate between different types of bacteria?

    3. Why is it necessary to sterilize the loop between streaks when streaking for single colonies?

    4. Define and/or explain the use of the following:

    (a) synthetic medium

    (b) agar

    (c) broth

    5. A bacterial species is inoculated on EMB agar.

    (a) The bacteria do not grow. Why?

    (b) If the bacteria ferment lactose, what would you expect to see?

    (c) The bacteria produce clear colonies. Why?

    6. What medium would you use (TSA, EMB, MS) if you wanted to determine if a Staphylococcus isolate could ferment mannitol? Describe what you would see on this medium.

    7. If you were testing water for the presence of fecal coliforms, what sort of medium would you use: TSA, EMB agar or MS agar? If fecal coliforms were present, what would their growth characteristics be on this medium?