Petri Dishes; Petri dishes everywhere!

Have you seen photos of petri dishes circulating the inter webs recently? There are a ton of kitchen biologists trying to grow stuff and spreading stuff on it and trying not to grow stuff, so naturally I wanted in on the action. When my friend said she had purchased some Petri dishes I gathered as many cleaning solutions as I could and headed over to an evening of fun at her house. 

Now this Petri dish thing went on for several rounds, so before you draw conclusions please read the whole adventure. It was a sh*t show to say the least. This could also upset a lot of my fellow essential oil enthusiasts, so hold on to your butt... I'm about to drop a whole lot of truth up in here. You should also ask yourself this question up front; what do you expect out of a good "cleaner"?


Round 1 - So you think you're a Biologist?

Here we are at my friend's house. We have a source of crud (her husband's phone), some Petri dishes, some sterile swabs, and some assorted cleaners. We used this little kit which came with some great instructions which informed us of more than we thought we knew about using Petri dishes. Our plan was to test several cleaners to mimic another experiment floating around the interwebs.

We were armed with cleaners from friends and family (thanks for the donations!) and made our list:

  1. THC - Thieves Household Cleaner (a Young Living Product)
  2. Thieves Essential Oil (a Young Living Product)
  3. Tea Tree Essential Oil (a Young Living Product)
  4. White Distilled Vinegar
  5. Mrs. Meyers Cleaner
  6. Method All Purpose Cleaner
  7. Lysol All Purpose Cleaner
  8. Fantastic All Purpose Cleaner
  9. Clorox Cleaner w/ Bleach
  10. Control (no cleaners applied)

The Plan:

  1. Using bottled water and a sterile swab gather grime from the phone
  2. Smear the grime on the agar using the quadrant technique (sounds fancy, right? Pinky up)
  3. Apply a drop of cleaner in the center of each plate
  4. Incubate
  5. Wait
  6. Record Results

The Results: 

This wasn't the best set up for the tests, but you get an idea of how some of the cleaners perform.

  • We Hoped it would work and it did:
    • #2 Thieves and #3 Tea Tree impressed the heck out of me.
  • We Thought it would work and it didn't:
    • #4 Vinegar was surprising as so many people use this on a regular basis for green cleaning, and #8 Fantastic didn't have the results I would think it would.
  • Green Cleaning - I'm a skeptic: 
    • #5 Mrs. Meyers is clearly not doing much and #6 Method impressed me.
  • The whole reason we did this:
    • As for #1 THC? Well, this was disappointing to say the least. There are many other Petri dish experiments on the interwebs that show different results. Much different. We needed to seek help on this one. 
1. THC - Thieves Household Cleaner, 2. Thieves Essential Oil, 3. Tea Tree Essential Oil, 4. White Distilled Vinegar, 5. Mrs. Meyers Cleaner, 6. Method All Purpose Cleaner, 7. Lysol All Purpose Cleaner, 8. Fantastic All Purpose Cleaner, 9. Clorox Cleaner w/ Bleach, 10. Control (no cleaners applied), 

1. THC - Thieves Household Cleaner, 2. Thieves Essential Oil, 3. Tea Tree Essential Oil, 4. White Distilled Vinegar, 5. Mrs. Meyers Cleaner, 6. Method All Purpose Cleaner, 7. Lysol All Purpose Cleaner, 8. Fantastic All Purpose Cleaner, 9. Clorox Cleaner w/ Bleach, 10. Control (no cleaners applied), 


The F-ups:

  1. I used the same swab and water over and over, so the grime built up plate by plate. I started with the control (10) and ended with THC (1), so the last few plates had an uphill battle. 
  2. I accidentally spilled a lot of lysol on plate 7, so it had an unfair advantage.
  3. We put the labels smack dab in the middle of the plate, so it was hard to see the agar where we applied the cleaners. 
  4. Incubating is no joke: we tried a box with aluminum foil and a small incandescent bulb, but we couldn't get it above 80 degF, so I brought the box home and set it up under a heat lamp we had. 

Round 2 - Consulting a Biologist

Thankfully I have a good friend who works with Petri dishes all day every day, so I reached out to her and told her of our epic fail. She may have rolled her eyes, I can't tell we were talking via text, but she was willing to help and had some ideas on how to improve things. I hoped on Amazon, ordered another set of Petri dishes, and set up a new plan.

She confirmed my suspicions of improper and uneven contamination of the first set of plates. Using the same swab and water over and over only increases the grime as you move forward with the plates. We needed a way to ensure even contamination of the plates. My friend recommended an experiment she tried in college: set the open dishes in your shower over night. That's right friends, no swabs or contact with any surfaces here. If we actually grew something this was a game changer: gross.

To save some money, and plates, she confirmed it was OK to split the plates: 1/2 control and 1/2 experiment with a cleaner. Phew! If not I was potentially setting myself up to break the bank!

I decided completing the whole array of cleaners was unnecessary, so I picked two to proceed with: the Thieves Household Cleaner (THC) and Clorox Cleaner w/ Bleach. 

The New Plan:

  1. Split the plates with a sharpie.
  2. Swab two cleaners on one half of the plates: THC vs. Clorox Cleanup
  3. Leave the other side untouched
  4. Place in shower overnight
  5. Move to incubator
  6. Wait and record

The Results: 

Well here we are again - NOT what I had expected. Both sides look the same, and we know Clorox works, so there's something amiss here. My conclusion? I swabbed the cleaners BEFORE placing them in the shower for contamination. The key point, and remember this for later, is that neither Clorox nor Thieves Household Cleaner prevent growth. 


The F-ups:

  1. I used the cleaners prior to contaminating the plates, so this test actually shows if the cleaners can prevent contamination.

Round 3 - Contamination THEN cleaning

Now that we know we need to use the cleaner as a cleaner, not a preventative measure, let's try this again. This is the exact same setup us before with one tweak on the order of operations...

The New New Plan:

  1. Split the plates with a sharpie.
  2. Place in shower overnight
  3. Swab two cleaners on one half of the plates: THC vs. Clorox Cleanup
  4. Leave the other side untouched
  5. Move to incubator
  6. Wait and record

The Results: 

After one day of incubating... this looks promising! Looks like I scrubbed a little hard with the Clorox, though as I tore the agar.


After two days of incubating... Still looking good! THC is showing a few spots, but still remarkable. 


After three days of incubating... Holy sh*t you guys, it worked! IT WORKED! It isn't perfect, but I'm pleased with the results! After all THC is much kinder to my family and safer around by kids!

But wait a minute... I used full strength THC, not diluted like I use in everyday applications. Crap. If you think there's a round 4 coming you would be right!


The F-ups:

  1. I tore the agar. I don't believe this affected the results, but I wanted to note this.
  2. I used full strength THC which no one actually cleans with. 

Round 4 - Diluting the Thieves Household Cleaner

Here we are again: more Petri dishes, more swabs, more cleaners, more grime. This time I planned to use the bottles of diluted THC I have and use on a daily basis. 

The New New New Plan:

  1. Split the plates with a sharpie - I'm getting really cheap so I used 4 quadrants
  2. Place in shower overnight
  3. Swab diluted and undiluted THC cleaners on the quadrants of the plate
  4. Leave one quadrant untouched
  5. For S&Gs I started a second plate and put some other undiluted essential oils on it
  6. Move to incubator
  7. Wait and record

The Results: 

After one day of incubating I gave up. I went cheap and utilized Q-tips from my bathroom vs. the sterile swabs they include in the kit (they just didn't provide a lot of those). From Round 1 we know Thieves shouldn't look like it does, so I pulled the plug early and regrouped. Round 5? You got it!


The F-ups:

  1. I used the cleaners already on hand, and I don't use bottled, boiled, or distilled water. I'm not sure if this affects the result. 
  2. I used Q-tips from my bathroom cabinet, not the sterile swabs in the kit
  3. Splitting the plate into quadrants, not halves, but be too much to ask of one little plate.

Round 5 - Let's sterilize everything

The last round taught me sterilization is hard people. Like really hard. Alas, I gave it a shot. I boiled some water, mixed up fresh THC, and contaminated some plates. 

The New New New New Plan:

  1. Split the plates with a sharpie.
  2. Place in shower overnight
  3. Boil water to use in diluting the THC
  4. Swab two dilution ratios on one half of the plates: 15:1 and 30:1
  5. Leave the other side untouched
  6. Move to incubator
  7. Wait and record

The Results: 

After one day of incubation...This isn't looking good.


After three days of incubation... this sh*t is hard. I have no idea why there is more on the cleaner side vs. the control. Clearly somewhere I went wrong. The dish I mixed the cleaner in may not have been sterile, the eyedropper to measure accurate drops may not have been sterile (both despite my best efforts to expose them to steam and boiling water prior to using them). 


The F-ups:

  1. I used a potentially non-sterile dish to mix up the cleaners
  2. I used a potentially non-sterile eye dropper to measure the water and the cleaners
  3. I may not have boiled the water long enough - I didn't set a timer
  4. Through all this I wasn't wearing sterile gloves, so despite washing my hands I may have added contamination.
  5. I may not have "scrubbed" well enough. There's two ways to clean; kill or remove, and I believe THC is a good way to remove the stuff you don't want around.

Final Conclusions

Alright, so if you made it through all that you're probably thinking "Wow... those results are awful!" On the contrary. These results actually taught me a lot and proved what I have believed for years; your house isn't nearly as clean as you think it is or can be. It also taught me these Petri dish experiments are damn hard and should be left up to the professionals. No one wants me in their lab! There are things I could have done differently and perhaps in the future I will. 

First, let's discuss good vs. bad. There are several varieties of agar you can use: some grow the scary stuff, some grow the mostly harmless stuff. These plates were from a science kit for children so they only grow the harmless stuff. Some of this is stuff you want around! In fact many of us regularly consume this good stuff on a daily basis (probiotics anyone?). Now anything that kills the bad stuff we don't want around is also going to kill off the good stuff. This is why we take extra probiotics and eat yogurt to combat diarrhea and yeast infections when we are put on an antibiotic. The next time you feel the need to sterilize everything in your house think about this. 

Next, let's talk about cleaners. What do you expect a good cleaner to do? Do you want to clean dirt, grime, grease, etc? Does a cleaner need to kill stuff in a Petri dish? For me a clean house is the first option - I don't want you to come to my house and see grease on the stove, handprints on my walls, have sticky feet walking across my floors, or see grime in my bathroom. If you remove the dirt, there is less surface area and less chance of the bad stuff sticking around. You can also remove a lot of the petri dish stuff by wiping it away, not with chemicals. If you expect to find clean swabs off every surface in my house, though, you should probably stay home. You should probably seal yourself up in a sterile bubble, too, if we are keeping it real. 

Sterilization; wowzers. If setting Petri dishes in a shower and seeing the contamination on them doesn't make you say "Hmmm" then I don't know what will. Before anyone claims my shower is dirtier than yours because "You use a cleaner that clearly doesn't work" let me squash that myth; I pay someone to come clean my house once a week and she has NOT converted to all the green cleaning products I use myself on a regular basis. I invite you to buy your own petri dishes, though, and run your own tests. Bonus points if you come back here and share! 

All that being said, where do I stand on Thieves Household Cleaner? I'm still loving it and I'm still using it. It cleans, and cleans very well. I've even used it to clean my carpets and floors after my dog pooped in my house. I've been using it for months and my family has been healthy, dare I say healthier than they have been in a long time. I'll spare you the spiel about removing toxins and feeling more energetic, all of that is in many of my other posts. What if you just can't stomach this and you NEED to find green cleaning options to clear up those Petri dishes? What if the yuck is amuck and you need to kill kill kill? There are a few options:

  1. Add a capful or two of Hydrogen Peroxide to your THC. THC is great at cleaning the grime, and the hydrogen peroxide will take care of the stuff you don't want around. 
  2. Steam it! High heat can wipe out a lot of what is out there. 

Before I conducted these experiments I spent a lot of time reading some of Dr. Annie's Experiments and I have to say of all the experiments I've seen I believe hers. She has the credentials, she doesn't BS, she documents her experiments well, and she is a graduate of Ohio State. 😍 Since she uses non-compliant words  I'm not allowed to link her page directly, but you can Google Dr. Annie. Compliance; just another reminder of why I wish I lived in Canada...

The last point I would like to make is that Thieves Household Cleaner and many other cleaners in NO WAY make any claims that they kill bacteria (There... I said it!). Read your labels; most of us just assume they do more than they can do. Cleaner vs. Disinfectant - there is a difference. 

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