Earlier this week we put a nice bow on our diversity of life unit. We concluded by watching our favorite science show, Mythbusters. Seeing that we just finished our lesson over bacteria, we decided to watch an episode that dealt with a classic germiphobe myth.....the double dip.
In episode of Mythbusters, Adam and Jamie take on this myth (among others) by using very similar materials that we have used in our previous lessons. The task was to take agar petri dishes and swab them with samples from the two dips, cream based (sour cream) and liquid based (salsa). After the samples were collected, they then took samples after double dipping and a sample from spitting dip back into the bowl.
So is double dipping really as bad as putting your whole mouth in the bowl? After a long process Adam and Jamie came to the conclusion that there are far more germs already living in the dips themselves and that double dipping did not produce enough bacteria to make enough of a difference.
So naturally myself and my students decided to test this experiment ourselves. We set up a experiment in which we took samples of my mouth, chips, salsa, and of course my double dip. After letting our petri dishes sit for the weekend, here are our results.
Mouth - Despite the fact that I own the dirtiest water bottle in town, the sample from my mouth did not produce any sufficient colonies of bacteria.
Chip - The sample from the chip did produce several colonies, the most noticeable the one located at the top of the petri dish.
Salsa - As you can see, this dish produced the most bacteria colonies in our experiment, there are about ten colonies that can seen in this photo.
Double Dip - Finally the double dip produced the about the same about of colonies as the regular salsa did, proving that I did not transmit a sufficient amount of bacteria into the salsa.
Just the same as Adam and Jamie, my students and I called this one busted. As you can see from the pictures, a germiphobe should be more concerned about the salsa they are eating instead of the double dip.....so tell the germiphobe in your life to just relax.