Science Buddies: "Ask an Expert"

Hi,
So for my semester-long Honors Biology research project, I am growing bacteria from phones.
I purchased all of my materials and have waited three days, but no bacteria are appearing to grow in my Petri dishes. I did some research and the only thing that could be wrong, it seems, is the agar I bought.
https://www.homesciencetools.com/agar-6-g-dehydrated

I bought this dehydrated agar. On the website, it stated that it was a "pure agar base (no nutrients added)." I realize this is a problem but it also said, "This agar does not have nutrients added to it; however, since it's an organic substance (made from seaweed), it's a medium that encourages bacteria growth." I read this and thought it would be fine to buy.

Will the bacteria still grow or do I need to redo my experiment? I need 40 data points or samples, so this is almost impossible to redo due to costs and shipping time! Is there anything I could do to "salvage" my project? If it comes down to me needing to redo the project, is there any way for me to not have to go out and swab the phones again? Like, could I swab the top of my original Petri dishes and transfer the sample to the new Petri dish?

Thank you!

Hi trinityclub246,

Have you tried incubating your samples? If you wait a few more days, I am sure that bacteria will start growing on the agar. However if nothing is growing, you can try making a simple gelatin agar using some unflavoured gelatin and beef stock cubes and table sugar. Your bacteria may not be growing because if wasn't placed in a warm or enriched environment.

Hope this helps!
CMS

Is it ok to leave Petri dishes in the oven at 90 degrees F all day as a substitute to an incubator?

moderator note: I merged this post with your previous post since it is related to your same project. Science Buddies quidelines requests that you keep your questions in the same topic so the experts can see that you have follow-up questions. Thank you.

Hi trinityclub246,

I wouldn't reccomend leaving Petri dishes in an oven. It can be quite dangerous and unsanitary, especially if your petri dishes become contaminated. You can try making an incubator using a carboard/styrofoam cooler and put a lightbulb inside the box. Make sure to put a cup of water inside the box for humidity. Try seeing if the temperature remains constant.

Hope this helps!
CMS