Inquiry on Proper Treatment of Bacteria

[Amazingrace98]

For a project which includes treating pathogenic bacteria with homeopathic remedies, what would be the proper method for treatment? Obviously, if I am choosing to test the affect of lemon juice on Bacillus Cereus I am not just going to squeeze a lemon over a petri dish and hope for the best. I cannot find any helpful books or websites on how to do this although I am sure that the answer is out there somewhere. Also, since Bacillus Cereus usually resides in the stomach after it is ingested (Bacillus Cereus causes a type of food poisoning), is there a substance I could add to the petri dish to mimic stomach acids as well as adding the homeopathic remedy? Again, I do not know the proper method for adding anything to a petri dish aside from using a sterile swab and swabbing the bacteria from the culture to the dish. Any helpful personal knowledge, website links or book titles would be much appreciated.

[deleted-291782]

Hello and thank you for your question.

In terms of adding treatments to your petri dishes with bacterial colonies, I would recommend adding these to the agar you use prior to it solidifying and streaking the plates. In our lab when we grow colonies, we typically grow them under antibiotic selection. So when we prepare agar formulations, we will have the agar sterilized, then add an antibiotic to the agar. Then we pour the agar in the petri dishes to allow it to solidify. I would recommend this as opposed to applying a layer of treatment over the cells. To do this properly, you can measure a certain amount of your treatment out and place it in a known volume of agar to be placed in each dish; that way, you know what the final percentage of your treatment is. For example, you add 1 mL of pure lemon juice to 9 mL agar, giving you a growth medium containing 10% lemon juice. Additionally, you can have control dishes that contain no treatment with the same bacteria.

As for trying to mimic the stomach environment, you could try to add some dilute hydrochloric acid (which is produced naturally by the stomach) to your agar plates. I would advise not using a high concentration though (perhaps a dilute preparation like 0.1 M for safety considerations). You could add this in a similar way as your main treatment.

Let me know if you have further questions and I'll be happy to help.

[SciB]

Hi,

Bacillus cereus is a human pathogen and schools and science fairs have strict guidelines that may limit the use of potentially harmful bacteria. Are you certain that you have permission to use B. cereus? Will you be able to do the work in an appropriate lab? I believe B. cereus must be used in a biosafety level 2 hood and incubator and you must wear gloves, eye protection and a lab coat (http://www.dehs.umn.edu/bio_pracprin_st ... xample.htm).

Here is some information regarding standard guidelines for projects involving microorganisms, as well as safety tips:
https://www.sciencebuddies.org/science-f ... ?from=Blog
https://www.sciencebuddies.org/science-f ... fety.shtml

I would recommend that you reconsider using pathogenic bacteria in your homeopathic experiments and work with the standard safe lab microbe, Escherichia coli K12. The results will be just as meaningful and you avoid the risk of human illness.

As for testing various compounds for antibacterial activity, the usual method is to plate a lawn of bacteria on a Petri dish and place several small round filter paper disks on the agar surface. A small amount of each test compound is pipetted onto a disk and the plate is incubated at 37C for 24-48 hours. A clear area will appear around the disks where bacterial growth is inhibited. Here's a description of the method: https://en.wikipedia.org/wiki/Agar_diffusion_test

If you need more information about performing these experiments please ask.

Good luck!

Sybee