Bacteria Bust (Bacterial Plates)

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What You Do:

Talk with students about the different types of bacteria, where they are found, and if bacteria are “good” or “bad”.

Pairs of students sample their environment for bacteria to test a hypothesis.

Bacterial plates are incubated for 24 hours to one week.

Students examine the bacteria gown on their plates to answer their scientific question.

What You Need:


Sharpie ( 1 per class )

Agar Bacteria Plate  ( 1 per pair of students )

Cotton Swab ( 1 per student, have a few extra )

Bacteria Bust Worksheet ( 1 per student )

Bacteria Bust Presentation ( 1 per group )

What’s Happening:

An agar plate is a Petri dish that contains a growth medium (typically agar plus nutrients) used to culture microorganisms or small plants like the moss Physcomitrella patens. Individual microorganisms placed on the plate will grow into individual colonies, each a clone genetically identical to the individual ancestor organism (except for the low, unavoidable rate of mutation). As a colony, we can see the bacteria, even though we can’t see them one on one. Different types of bacteria have a different appearance, which allows us to tell them apart.

Selective growth compounds may also be added to the media, such as antibiotics. These compounds allow bacteria with certain genes or traits to grow, while others will not.


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