Anonymous asked in Science & MathematicsBiology · 2 months ago

How would I conduct serial dilutions from an agar plate and how many by looking at this plate (With pic)?


please include a step by step as I am highly confused. I have been told to do serial dilutions from this plate

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1 Answer

  • Anonymous
    2 months ago

    A serial dilution is a method of diluting over the course of several dilutions.  The loop your teacher refers to is called a calibrated loop.  Standard calibrated loops hold 10uL of fluid in the loop.  That is useless when you are taking about colonies from a plate.  One method would be the pour-plate technique, but it sounds as though your teacher just wants you to transfer colonies (with the loop) from the plate to some liquid, and then use the loop to transfer that dilution to a new plate, streak it out, grow it, etc.  The 10uL of fluid which you remove from your dilution (10mL of water), so 10uL/10mL is a 1:1000 dilution each time you do that.

    But that is useless when using colonies off the plate, because you have no idea how many bacteria you are looping off the plate.  And btw, the use of water as the diluent makes no sense.  Buffered media broth is the standard diluent.  But for the purposes of this ill-planned lab activity, each time you transfer with a 10uL calibrated loop from a volume of 10mL, you are diluting the sample 1:1000.

    And if that makes no sense to you, then you are not cut out for this class.

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