Jenny ZackGrade 9

The problem addressed in this experiment was whether or not bacteria can be used to identify suspects in a crime scene.

Forensic scientist can use bacteria to identify suspects

Fingerprints are extremely easy to get rid of

Staphylococcus, Corynebacteria, Streptococcus, Escherichia coli, Myobacteria, and Haemophilus

Microbiome

If the bacteria are treated with antibacterial cleaner and mouthwash, then they will be ineffective as identifiers.

If the bacteria are left out for three days, then they will multiply, and can be used as identifiers.

12 Petri dishes Tryptic soy agar Easy Gel coliscan 18 sterile cotton swabs 3 Inoculating loops Antibacterial cleaner Mouthwash Paper towels Sterile surface Incubator

First, I made a tape square on the surface of a table. I then made multiple bacterial handprints within that square to let it sit for the weekend and see how time affects it.

Next, I made a bacterial handprint on a table’s surface and sprayed the table with antibacterial cleaner. I then wiped it with a paper towel and took three samples.

For the mouthwash group, this routine was repeated, but I wiped the bacterial handprint with mouthwash.

When making the control samples, I made a bacterial handprint and took three samples without treating it with anything.

For time, the same process was repeated, however the bacteria was allowed 3 days to sit prior to testing.

Lastly, I placed all nine petri dishes in the incubator at 26 degrees Celsius.

All petri dishes were taken out of the incubator after 3 days of growth.

When examining the samples, I counted the # of colonies and colony types. I distinguished colony types by color.

After I examined the petri dishes, I put them in the fridge to preserve them.

The hypothesis was partially supported because despite the use of the antibacterial products and mouthwash, bacterial growth was comparable to the control samples.

Also, bacterial growth was greater in the time samples than the control.

Given the results it is inconclusive whether or not these bacterial handprints can be used to identify suspects

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Madrigal, Alexis. “Your Leaving a Bacterial Fingerprint on Your Keyboard.” Wired. Conde Nast Digital, 2010. Web. 29 Sept. 2011. <http://www.wired.com/ wiredscience/ 2010/ 03/ keyboard-microbiome/>.

Martinez, Edecio. “Your Germs Might Be as Unique as Your Fingerprints.” CBSNews. CBS Interactive Inc., 2011. Web. 29 Sept. 2011. <http://www.cbsnews.com/ 8301-504083_162-20000536-504083.html>.

“Telltale Bacteria.” The Engineer. Centaur Media plc, 2011. Web. 26 Sept. 2011. <http://www.theengineer.co.uk/ news/ telltale-bacteria/ 1001384.article>.

Thank you to everyone in the audience for listening to my presentation! I would be happy to answer any questions

you may have about my project!