8 thoughts on “D21 – McMichael

    1. Hi Alex,

      The absorbance values essentially signify how much bacteria is in the well. The spectrophotometer sends a light through each well and a greater amount of bacteria will result in more of the light being absorbed, therefore a higher absorbance value. For this experiment, we wanted to see a high absorbance value for the Lactobacillus Acidophilus, meaning that there was bacterial growth. However, if we were testing the effect of a compound on the growth of Salmonella, we would want to see a low absorbance value, meaning that the compound had killed/lowered the amount of Salmonella in the well.

    1. Hi Chrisanna,

      Correct me if I’m wrong, but I think you’re asking what the role of the media is. The media is the substance that the L. acidophilus is being dissolved in. In this case, using the MRS broth as our media provided the nutrients and environment that the Lactobacillus needed to grow. Therefore, the media tells us what environment and nutrients the bacteria needs to thrive.

    1. Hi Makenzie,

      Co-culturing (ie growing them in the same via/plate/etc) the L. acidophilus and the Salmonella Typhimurium would allow us to observe the differences in bacterial growth and if the L. acidophilus is able to combat/outcompete the growth of the Salmonella.

  1. Do you know if there’s a concentration of L. acidophilus that can begin to cause harm to human health?

  2. Hi Spoorthy,

    From the studies we read, L. acidophilus has only caused harm in extremely rare cases. If you’d like me to find these articles for you, I can! If we wanted to attempt to determine this value in the lab, we would need to perform a max dose experiment.

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