We all know, at least in concept, about the millions and billions of bacteria and other little beasties currently making a living on our bodies right this minute. You know they’re there, but since you can’t see them, there’s a bit of distance between you and all of your little friends.
However, that doesn’t always have to be the case. Tasha Sturm, a tech in Cabrillo College’s microbiology, physiology, and anatomy labs, created this petri dish of all the microbes hanging out on her eight-year-old son’s hand after a day at the playground.
Yes. All of that. On your hands. Right now.
We know, you’re already reaching for the sanitizer.
Still, you have to admit, even as you are furiously rubbing your hands on your pants in a frantic (but futile) attempt to clean them, seeing microbes at such a scale is impressive.
So how did Sturm do it? First, she poured a solution of tryptic soy agar (TSA) and water into a sterile petri dish and let it solidify. Then, her son pressed his hand to the agar, which lifted off the small amounts of bacteria that would become the colonies you see here. The petri dish was then covered. Sturm incubated it for a day or two, which spurred growth. In room temperature, the colonies of bacteria and fungus continued to grow. Eventually, the once-invisible handprint turned into the alien-looking ecosystem you see here.
Close-ups of some of the bacteria present in the dish.
You can create something like this yourself if you’re curious about what you and your kids picked up at the park. You can order the materials and find a more detailed description of the process online. However, once the bacteria and fungus start growing enough to be visible to the naked eye, don’t open the petri dish; breathing that amount of material in can be hazardous to your health. We don’t recommend that just anyone do this without seriously looking into it beforehand.
You may now go wash your hands for 20 minutes.