Science Buddies: "Ask an Expert"

Where can my son go to find out what type of bacteria is found on dollar bills. My son is in the 10th grade and want to do a follow-on project to his 8th grade project. He was able to use a high school science class to incubate his slides and saw the bacteria grow. He was able to identify that bacteria were found but now he wants to identify some types of bacteria found on the bills. We know this can be costly so we are looking for low budget situations.

Hi,

As you said, identifying bacteria can be a complicated and expensive proposition. Simply growing them from swabs on nutrient agar Petri dishes is one inexpensive way to go but one can only identify a few species that have distinctive colors or forms this way.

There is a company called Carolina Bio that sells kits for bacterial ID that are not too costly: http://www.carolina.com/catalog/search- ... SearchForm

One of the most common tests that bacteriologists do in ID’g unknown bacteria is called the Gram stain and that is included in one of the kits from Carolina Bio. There are also some biochemical and metabolic tests that can be done, but these will usually only ID the family or genus. To ID the species, scientists use genetic methods such as the polymerase chain reaction (PCR) which requires expensive reagents and instruments.

Here are some sites that have useful general information that your son can read about growing and identifying bacteria:

https://www.sciencebuddies.org/science- ... p007.shtml
https://www.sciencebuddies.org/science- ... ates.shtml
http://www.stevespanglerscience.com/lab ... g-bacteria

You will probably be using nutrient agar to grow the bacteria. This is a rich medium containing protein and meat extracts along with salts and glucose. Many bacteria and fungi will grow on nutrient agar and some of them are harmful or even deadly to humans, so you need to be very careful when growing bugs that you collect from the environment. Once you swab the plates from the bills, attach the lids to the bottoms with some tape so they can’t come off accidentally. https://www.sciencebuddies.org/science- ... fety.shtml

I hope this helps. Let us know when you have more questions.

Good luck!

Sybee

Thanks. This information is very helpful.

You are welcome. Let us know when you have more questions about your project.

Good luck!

Sybee