Bread Mold Kills Bacteria


[MUSIC PLAYING] Microorganisms are small, so
small you can’t even see them unless they cluster together. Each of these dots is
really millions of bacteria. But down on a microscopic
scale, mold and bacteria fight vicious battles. Their resources and
territory are scarce. And the stakes are survival. Mold has a powerful chemical
weapon in its arsenal. I”m Emily. And I’d like to show
you Alexander Fleming’s famous discovery that
bread mold kills bacteria. Here’s some fresh bread. I’ll add some water,
because mold loves moisture. Now, I need bacteria, which you
can find basically anywhere, including in your mouth. This Petri dish has
a Jell-O-like layer of agar, food for the
bacteria in my saliva. It’ll take a few days before
the colonies of bacteria are big enough to see. Let’s set up place to
grow the mold and bacteria in a contained way so it doesn’t
spread or infect anything else. These bell jars will help make
sure that nothing contaminates the experiment. And the experiment doesn’t
contaminate anything else. I’m back. Well, there’s a lot of bacteria. Each cell divided and
divided and divided to make a colony
that we can see now. So bread mold also grew. Let’s see if it can
kill some bacteria. I’ll take a chunk of bread
mold and let it do its work. Legend has it that in
Fleming’s original experiment, some mold from
his lunch sandwich accidentally dropped
into his Petri dish. Let’s take a closer look. Then we’ll come back later
and see what’s changed. Under a microscope
mold looks something like this yellow model. And mold attacks
bacteria cell walls, represented by these cups. Mold secretes a
chemical, penicillin, which damages bacteria
cell walls, stamping out the competition. This means the bacteria
surrounding the mold will die. We’re looking for bacterial
death around the mold. Do see where the bacteria
have died around the mold? This is called
the ring of death. Mold and bacteria have been
battling for millions of years. Mold keeps coming up with
new weapons, antibiotics. And bacteria keeps coming up
with new shields, resistance. Alexander Fleming, after
treating wounded soldiers in World War I, was
the first person to realize how useful
antibiotics are for treating infection. Today, we remember him for
his discovery of penicillin. I think his experiment
is really neat. And I hope you do too.

6 thoughts on “Bread Mold Kills Bacteria

  1. Waiting to watch next video for this second part to another experimental ways to do the dilution of bacteria from the bread mold. Another some suggestions for experimental games, try to use some organic soup methods.

  2. indeed it s proven that penicillin was discovered years before him, and that stupid story of sandwich falling on to his work also…

  3. thanks.
    mold causes stomach pain
    source :
    'Molds can irritate the digestive system causing diarrhea, dehydration, nausea or stomach cramps'
    in http://enhs.umn.edu/current/5103/molds/absorption.html
    from google (mold stomach ache) result 2

  4. Thanks so much for breaking it down to the simpler way. Been trying to learn this for a while now. Finally found you. Much appreciated for making it so simple even my dumb ass understands

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