Ask an Expert: Temperature for Incubation of Petri Dishes: LB Agar Plates
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Temperature for Incubation of Petri Dishes: LB Agar Plates


Hello,
Here are the steps I did for my science experiment,
- I coughed on Luria Broth agar plates with three different face coverings (surgical, cloth, neck gaiter) and no mask.
I then sealed the plates with masking tape and labeled them.
I put these plates into a plastic container next to a portable heater and a lamp.
The DIY incubator and plates were at the temperature of 104 degrees for about 14-16 hours. It's been two days since I started this project and I haven't seen any bacterial colonies on my control group (the no mask trial). I'm unsure if the high temperatures killed the bacteria from my cough. Should I unseal the Petri dishes, cough on them again (redoing the procedure), and reincubate?
If it helps, these are the Petri dishes I ordered: https://www.amazon.com/EZ-BioResearch-Bacteria-Science-Book/dp/B0165PQST0/ref=sr_1_1?dchild=1&keywords=EZ+BioResearch&qid=1611806294&sr=8-1
Picture of my incubation set up before I removed the lamp, the lamp is now removed to reduce the temperature: https://prnt.sc/xqkbq7
Please respond to this and help me as soon as possible, as my project is due in 5-7 days.
Also, do you have any name ideas for this project? I was thinking, "Stop the Spread!" or "Viruses". Any suggestions are accepted!

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Re: Temperature for Incubation of Petri Dishes: LB Agar Plates
Hi!
That's a timely project! While 37 degrees C is the average optimal temperature for bacteria to grow, I don't believe 40 C is high enough to kill your bacteria. Additionally, 2 days is probably too short of a time for you to begin to see bacterial growth. However, these are hypotheticals since the bacteria coughed onto the plate is unknown and is probably a mix of many different bacteria. I'd recommend giving it a few more days, or, if you have extra Petri dishes, repeat the experiment separately to ensure you get results. Good luck!
- probiotics
That's a timely project! While 37 degrees C is the average optimal temperature for bacteria to grow, I don't believe 40 C is high enough to kill your bacteria. Additionally, 2 days is probably too short of a time for you to begin to see bacterial growth. However, these are hypotheticals since the bacteria coughed onto the plate is unknown and is probably a mix of many different bacteria. I'd recommend giving it a few more days, or, if you have extra Petri dishes, repeat the experiment separately to ensure you get results. Good luck!
- probiotics