Schuby99
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Make a safe bacteria solution?

Postby Schuby99 » Mon Aug 31, 2020 3:45 pm

Yeast and water a safe bacteria solution?

My son wants to test effectiveness of social distancing on spread. The thought is he would make up a liquid solution with bacteria in it that he could spray (via spray bottle he says). Placing petri/agar dishes at various distances. Then measure the bacteria growth and compare.

Any suggestions for making a liquid solution that would have safe type/level of bacteria that could be sprayed. Had rad somewhere yeast would grow in agar dish - but not sure if mixing it with water would ruin it? Any advice greatly appreciated. Thanks!

probiotics
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Re: Make a safe bacteria solution?

Postby probiotics » Mon Aug 31, 2020 4:43 pm

Hi!

Sounds like a great experiment and an effective way to show the importance of social distancing. For bacteria, you can try purchasing E. Cold k-12, which is a strain that isn’t pathogenic. You could also try dissolving probiotic pills that don’t require refrigeration in water, as the probiotic bacteria wouldn’t be harmful. No matter what bacteria you choose, make sure to test in a place that can be easily cleaned. Some potential things to think about would be how well does the spray bottle simulate a human sneeze? Let me know if you have any more questions.

Thanks, probiotics

Schuby99
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Re: Make a safe bacteria solution?

Postby Schuby99 » Mon Aug 31, 2020 5:24 pm

Thanks!!!! Great advice.

cnoonan180
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Re: Make a safe bacteria solution?

Postby cnoonan180 » Thu Sep 10, 2020 9:27 pm

Hello,

This is a very interesting and important project idea!

For the bacteria, it would be best to use a species of bacteria that is not harmful to humans. The good news is: there are trillions of species of bacteria that live inside the human body are are actually beneficial to human health!

These types of bacteria can be acquired from many foods people eat such as “probiotic” yogurt and “cultured” cheese (both words in quotes indicate that these foods contain live bacteria). An easy and practical way to acquire some bacteria (that are not harmful to humans) to use as part of your son’s experiment could be from yogurt. You could do this by extracting the “live cultures” from yogurt labeled as “probiotic” or “cultured.” Here is a Science Buddies project that would help you to do this:

https://www.sciencebuddies.org/science- ... #procedure

If you choose to incorporate this bacteria extraction procedure into your son’s project, instead of dropping the yogurt onto the agar right away (as step 10 in the procedure tab of the link to the project above instructs), drop the yogurt you extract from the container into your spray bottle along with the distilled water. Then, spray this mixture onto the agar in your Petri dishes from various distances. Make sure that your spray bottle nozzle is adjusted so that the spray is similar to a garden hose or kitchen sink (although not as forceful), so that the spray provides a smooth and “singular” flow rather than, for instance, the type of spray a perfume bottle would expel. This is to ensure that all the bacteria makes it’s way into the Petri dish and onto the agar for your experiment so that enough bacteria will grow for you to see results. Also try your best not to puncture the agar as you spray the bacteria onto it, since this may make it more difficult to see the bacteria later on.

Hope this helps and feel free to reach out with further questions!
-cnoonan180

Schuby99
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Re: Make a safe bacteria solution?

Postby Schuby99 » Wed Oct 21, 2020 3:21 pm

Thanks so much for the reply. Very helpful!

Project was approved by his teacher and he is proceeding - Two questions if you have time?

1) Is there a specific type of agar that we should get? He asked me to order 2o pre filled petri dishes, but seems they have different types of agar (malt extract, soy, Etc)?

2) Any recommendations for the amount of yogurt to mix with amount of distilled water? Needs to be fluid enough to go through spray bottle/aerosolize - but enough probiotic to register?

Thanks again for the advice.

Charles

cnoonan180
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Re: Make a safe bacteria solution?

Postby cnoonan180 » Wed Oct 21, 2020 5:40 pm

Hello again!

Congratulations to your son for getting his project approved by the teacher! This is great practice for research endeavors that may include submitting a proposal to be approved by a research committee in the future.

Here is a Science Buddies article all about agar and how to choose the best type of agar to use for science fair projects: https://www.sciencebuddies.org/science- ... robes-agar

For your project, according to the article above and Science Buddies procedure for culturing yogurt bacteria, nutrient agar would be best. Petri dishes containing nutrient agar that are pre-prepared for use for your son's project can be purchased here:
https://www.carolina.com/prepared-biolo ... scibuddies

As for how much yogurt to mix with the distilled water, the Science Buddies procedure for culturing yogurt bacteria recommends that two drops of yogurt be dropped onto the agar in each petri dish along with two drops of distilled water. So, as long as the quantities of yogurt and distilled water in your spray bottle are about equal, this should provide enough bacteria to be sprayed onto the agar as long as the yogurt and distilled water are well mixed in the spray bottle. If possible, find a way to spray the yogurt onto the agar before you spray the distilled water onto the agar, although this may be difficult with a regular household spray bottle considering the thickness of yogurt.

Hope this helps and good luck with the project!
-cnoonan180

Schuby99
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Re: Make a safe bacteria solution?

Postby Schuby99 » Wed Oct 21, 2020 6:49 pm

Thanks!


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