Posts: 4
Joined: Mon Jun 24, 2019 5:25 am
Occupation: Student


Postby Shaaban » Mon Jun 24, 2019 5:45 am

Hi! I am an IB-student and doing an experiment for my extended essay. It is a kind of scientific article. In my experiment, I am looking at the antibacterial activity of honey. I am using different brands of honey and comparing it with antibiotic paper discs penicillin G 10 using disc diffusion technique. For bacteria growth, I tried to use a cheap method using cotton swabs to collect bacteria from surfaces like the door handle. The problem is that I think I grew anti-resistant bacteria since I did not get a zone of inhibition around my paper discs, contrarily my bacteria grew on them. I went and tried the well diffusion method but still did not get anything from it. I am now stuck and I don't know what to do, I've been trying this for a couple of weeks. Now I want to grow a bacteria that I will be definite that it will not anti-resistant but need to find a source to get this bacteria from. I heard that if I use raw milk in the agar, I will get a non-resistant bacteria, but did not find any method of doing that on the internet. Do you know anything about that?

Posts: 88
Joined: Sat Sep 01, 2018 4:14 pm
Occupation: Other Adult

Re: Biology

Postby 17eugenekim » Mon Jun 24, 2019 9:28 pm


That's an excellent experiment you've got going on and I understand the frustration! However, if you haven't already, I encourage you to continue to document the steps that you're taking and the data you're collecting, even if it's not expected or "desirable" - that's what research is, after all! For instance, what you're doing now - troubleshooting - is actually a separate hypothesis you're testing. You are hypothesizing that the bacteria is antibiotic-resistant, and now you are looking for non-resistant strains to test to confirm or refute that hypothesis.

You may actually be able to simply purchase some bacterial strains online. Sometimes they won't say specifically about their antibiotic sensitivity, but many of these commercially available kits or cultures are sold to use in the exact type of experiment you're conducting. So I find it unlikely that a batch you'll buy will be completely resistant. That would be my recommendation; I'm frankly not sure what other options I would offer.

In terms of cultivating your own non-resistant bacteria from scratch - unless another Expert wants to weigh in, I find it too difficult/tedious to try. I am not familiar with the raw milk procedure you mentioned and I'm not sure of any other surefire ways to prove that a strain is non-resistant without, you know, killing some of it with antibiotic.

It may very well be that the resistance is not your problem, and that's okay. But this step will help you determine for sure, and then you will have more hypotheses to test in your scientific process. Perhaps there are other points in your methodology that could be the culprit.

Return to “Grades 9-12: Life, Earth, and Social Sciences”