Effect of bacteriophages on bacteria of varying resistance

[deleted-1072348]

Hello,
I'm interested in doing an experiment on how the antibacterial resistance of bacteria affects how well bacteriophages are able to infect the bacteria. Since I will be carrying out this project for what is to me a lengthy amount of time, I just wanted to know if there are any issues with this experiment and/or if there are any ways it could be improved. Feedback would be greatly appreciated.

Thanks

[brandimiller610]

Hi hzab52,

I think this is a very interesting science fair experiment topic. I see no issues with this experiment, as long as you have adequate time to culture the bacteria, quantify phages, etc. and replicate your experiment three times. I am happy to help and possibly suggest ways to improve upon your experiment, but first may you provide some more details about your experimental design? For example, how many and which strains of bacteria (I assume E. coli) do you plan to use? How do you plan to quantify the bacteriophages in the different strains of bacteria with different levels of resistance? What are your controls? With such information, I can offer more suggestions and feedback.

--Brandi

[deleted-1072348]

Hi,

Thanks so much for reaching out. Sorry I was too vague in my first question, I'll try my best to clear things up. Time is not really an issue for me. For quantifying the bacteria, I plan on diluting a few small samples of each sample, manually counting the number of bacteria, and then finding the average to make my data as accurate as possible. I'll do this a few times as time goes on so I can roughly map the efficiency of the bacteriophage. I figured the lesser number of bacteria, the more had lysed, indicating how well the phage worked. Speaking of the phage, I plan on using either E. virus T2 or T4. The only thing I want to change is the resistance of the bacteria, so everything else will remain the same (including the amount of bacteria, amount of phages, and environment). I will also do the same procedure with antibiotics as well, depending on how easily I can get the materials needed. The one thing I am not sure about is how to obtain the different strands of e. coli. Should I look for different strands to buy directly, or is there a better approach for what I want to do?

Sorry if that was a lot and thanks for being patient

[deleted-1072348]

Hello,
I want to do an experiment that observes how antibiotic resistance affects how well bacteriophages can lyse bacteria. I have most of the elements of the experiment figured out, but I need to have antibiotic-resistant bacteria. (This project will be pre-approved and overseen by my teacher for my local science fair). I just wanted to know how I can get some, or if I should somehow manually make them antibiotic-resistant using increasing levels of antibiotics. I'd appreciate if someone could help with my issue.

Thanks

[MadelineB]

Hello hzab52,

Your last post looks like it's related to your earlier posts, so I have merged all your posts so that the expert who was helping you with the earlier posts can more easily see that you have a follow-up question.

Thanks and good luck with your projects!
Moderator

[brandimiller610]

Hi hzab52,

Thanks for following up -- the information you gave in your follow-up post is very helpful! I also apologize for my late reply to your questions.

First, your method for quantifying the bacteria sounds good. Just make sure you repeat your dilutions multiple times to ensure consistency with your colony counts -- from personal experience, it can sometimes be difficult to get consistent counts with bacteria! I also think your idea of doing the dilutions over a certain time period is good for illustrating the efficiency of the bacteriophage over time. Controlling the bacteria number, amount of phages, and environment are all good practices to ensure consistency and increase reliability of your data.

As far as obtaining the bacteria, your teacher/supervisor should be able to help you, but there are multiple vendors out there that sell frozen stocks of bacteria. ATCC (https://www.atcc.org/) is a common one, as is Carolina (https://www.carolina.com/). On these sites, you can do a very quick search for the E. coli strain(s) you would like and discuss with your supervisor about ordering. I think one strain would be enough; what I would suggest is using multiple antibiotics. Antibiotic resistance with E. coli is a growing concern, so I think this would be a better approach. Then, tying that in with the efficacy of the bacteriophage makes for a good project. You could make the bacteria resistant in the laboratory using plasmid cloning -- basically if a bacterium picks up a single drug-resistant plasmid, it can be become resistant to multiple antibiotics. I am not sure about the availability of antibiotic resistant E. coli online, but ordering it would be the easier route. I am happy to do some more research on that and follow-up.

I hope I have been able to help! Please feel free to follow up if you have any more questions or would like to discuss anything more about your project!

--Brandi