Analysis of E. coli growth dynamics during Lambda(vir) phage infection reveals phage decay

Table: MED9
Experimentation location: Reseach Institution
Regulated Research (Form 1c): No
Project continuation (Form 7): No

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Abstract:

Bibliography/Citations:

References1.Ofoghi B, Zeleznikow J, MacMahon C, Raab M. Data mining in elite sports: A review and aframework. Measurement in Physical Education and Exercise Science. 2013. pp. 171186.doi:10.1080/1091367X.2013.8051372.Luria SE, Delbrück M. Mutations of Bacteria from Virus Sensitivity to Virus Resistance.Genetics. 1943;28: 491. doi:10.1093/GENETICS/28.6.4913.KüchenhoffH. Coin Tossing and SpinningUseful Classroom Experiments for TeachingStatistics. Recent Advances in Linear Models and Related Areas. 2008; 417426.doi:10.1007/978-3-7908-2064-5_234.JACOB F, WOLLMAN EL.Etude génétique d’un bactériophage tempéré d’Escherichia coli.l. Le système genétique du bactériophage.Ann Inst Pasteur (Paris). 1954;87: 653673.5.Ryan EM, Gorman SP, Donnelly RF, Gilmore BF. Recent advances in bacteriophagetherapy: how delivery routes, formulation, concentration and timing influence thesuccess of phage therapyj php_1324 1253..1264. 2011 [cited 18 Nov 2023].doi:10.1111/j.2042-7158.2011.01324.xReferences1.Ofoghi B, Zeleznikow J, MacMahon C, Raab M. Data mining in elite sports: A review and aframework. Measurement in Physical Education and Exercise Science. 2013. pp. 171186.doi:10.1080/1091367X.2013.8051372.Luria SE, Delbrück M. Mutations of Bacteria from Virus Sensitivity to Virus Resistance.Genetics. 1943;28: 491. doi:10.1093/GENETICS/28.6.4913.KüchenhoffH. Coin Tossing and SpinningUseful Classroom Experiments for TeachingStatistics. Recent Advances in Linear Models and Related Areas. 2008; 417426.doi:10.1007/978-3-7908-2064-5_234.JACOB F, WOLLMAN EL.Etude génétique d’un bactériophage tempéré d’Escherichia coli.l. Le système genétique du bactériophage.Ann Inst Pasteur (Paris). 1954;87: 653673.5.Ryan EM, Gorman SP, Donnelly RF, Gilmore BF. Recent advances in bacteriophagetherapy: how delivery routes, formulation, concentration and timing influence thesuccess of phage therapyj php_1324 1253..1264. 2011 [cited 18 Nov 2023].doi:10.1111/j.2042-7158.2011.01324.xReferences
1.Ofoghi B, Zeleznikow J, MacMahon C, Raab M. Data mining in elite sports: A review and a framework. Measurement in Physical Education and Exercise Science. 2013. pp. 171–186. doi:10.1080/1091367X.2013.805137
2.Luria SE, Delbrück M., Mutations of Bacteria from Virus Sensitivity to Virus Resistance.Genetics. 1943;28: 491. doi:10.1093/GENETICS/28.6.491
3.Küchenhoff H. Coin Tossing and Spinning Useful Classroom Experiments for Teaching Statistics. Recent Advances in Linear Models and Related Areas. 2008; 417–426.doi:10.1007/978-3-7908-2064-5_23
4. JACOB F, WOLLMAN EL. Etude génétique d’un bactériophage tempéré d’ Escherichia coli. l. Le système genétique du bactériophage. Ann Inst Pasteur (Paris). 1954;87: 653–673.
5. Ryan EM, Gorman SP, Donnelly RF, Gilmore BF. Recent advances in bacteriophage therapy: how delivery routes, formulation, concentration and timing influence the success of phage therapyj php_1324 1253..1264. 2011 [cited 18 Nov 2023]. doi:10.1111/j.2042-7158.2011.01324.x

6.6. Hyman P. Phages for Phage Therapy: Isolation, Characterization, and Host Range Breadth. Pharmaceuticals 2019, Vol 12, Page 35. 2019;12: 35. doi:10.3390/PH12010035


Additional Project Information

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Research Plan:

In order to track phage-bacteria interactions, I used a spectrophotometer to follow the optical density over time of bacteria-phage mixtures with different starting bacterial population sizes. To do this, I used a 96-well plate design, where each row was a different dilution of bacteria with the same concentration of phage. To examine variability, I measured 11 replicates of each dilution and 1 control. I measured the optical density (OD) once every 10 minutes for 20 hours to track the dynamics of bacteria-phage interactions and bacterial growth. (Optical density measures the amount of bacteria in a solution.) In a second experiment, I wanted to see if phage decayed over time. I thus pre-incubated phage stocks by shaking them at 37oC for different lengths of time before exposing them to bacteria. I then took all the different time points of phage and put them onto the plates again with 11 replicates and 1 control, measuring OD every 10 minutes for 16 hours. I also wanted to test if the dead bacteria resulting from phage killing could affect OD, so I boiled bacteria to kill them, and I measured the resulting OD to see if bacterial debris from cells killed by another mechanism also affects OD.

All the plans for the experiments and calculations (like for serial dilutions) were designed ahead of time before each experiment began.

Questions and Answers

1. What was the major objective of your project and what was your plan to achieve it? 
Infections associated with bacteria resistant to traditional antibiotics claimed more than one million lives in 2019. To address this crisis, we need to develop new ways of killing bacteria, like those based on bacteriophages, which are viruses that specifically kill bacteria. The main objective of my project was to learn more about bacteria-phage interactions to find ways to potentially improve phage therapy to combat the antimicrobial resistance crisis. My plan to achieve this was to first confirm that I could measure the dynamics of bacteria-phage interactions by repeating the Luria-Delbruck experiment but using new forms of measurement that account for bacterial dynamics. I then looked to see if any anomalies arose in the measurements and studied those, because the unexpected dynamics are where we could generate new insights to advance the field.
      a. Was that goal the result of any specific situation, experience, or problem you encountered?  
The goal of studying phage-bacteria dynamics to help combat the antimicrobial resistance crisis emerged from learning about how massive the issue of the antimicrobial crisis really is. I then brainstormed about ways that we could learn more about alternatives to traditional antibiotics and learned about phages. But I also learned that phage therapies currently failed for largely unknown reasons, which sparked my interest in trying to see if I could better understand phage-bacteria dynamics and use those insights to come up with better phage therapies.
      b. Were you trying to solve a problem, answer a question, or test a hypothesis?
I was trying to solve a problem - that phage therapies are not as successful as had been hoped - by using dynamic measurements to test the hypothesis that there are unexpected interactions between bacteria and phages that occur over time. I further hypothesized that by better understanding phage-bacteria dynamics, we could propose ways to improve phage therapy. This could potentially help many people if successful.
2. What were the major tasks you had to perform in order to complete your project?
I had to learn how to grow bacteria and phage cultures, pipette them, perform serial dilutions, kill them with heat, and measure their optical density with a robotic spectrometer.
3. What is new or novel about your project?
I tracked phage-bacteria interactions using dynamics rather than just an endpoint analysis, which had not been done before. I did this because I wanted to learn more about their interactions, and I hoped that information obtained by watching the dynamics could potentially be used to improve phage therapy. Excitingly, I was successful in identifying a novel feature of these dynamics: phages were previously thought to be very stable, and are indeed they are stable at 4 degrees C, but I found that at body conditions of 37 degrees C, phages rapidly decay. This new insight suggests that current phage doses may be underestimated and that higher doses should be delivered to account for the decay that occurs within the body.
      a. Is there some aspect of your project's objective, or how you achieved it that you haven't done before?
Almost everything in the project was brand new to me. I learned how to start bacterial cultures, pipette, calculate the number of living bacteria, create dilutions of bacteria, use a spectrophotometer, use Excel to analyze and plot the data, find references to understand the background literature, and also how to write a full scientific paper.
      b. Is your project's objective, or the way you implemented it, different from anything you have seen?
It is very different as I was very new to the whole process. Pretty much, the entire process was different from anything I had physically done or seen in person before, and previous phage-bacteria studies used plates and endpoint assays, not dynamic measurements.
      c. If you believe your work to be unique in some way, what research have you done to confirm that it is?
I have spent hours looking through various academic journals, google, and any other source I could to find either references for my paper or to see if anyone else had done what we had and made those discoveries. There was a lot of good work that I found related to the topic, but none of it was exactly what I did.
4. What was the most challenging part of completing your project?
The most challenging part of this project was the learning curve with the new techniques I had to learn. I had to do the first experiment 4 times before my pipetting skills got good enough to have clean results. From there though, it got easier as I then knew how to pipette and was getting better at it.
     a. What problems did you encounter, and how did you overcome them?
The first couple trials didn’t go well, so I had to keep trying and changing things ever so slightly until I got reproducible and interpretable results. There were also some difficulties with time, as often school or other factors meant I didn’t have as much time to work on the project as I would have wanted.
     b. What did you learn from overcoming these problems?
I learned how to work in a lab, design my own experiments, and quantitatively interpret my results to help me design additional experiments. These are skills that I will keep with me and will really help with any future projects I do. That goes for all the skills I gained from this experience, and hopefully those future projects will be even better and allow me to gain even more skills.
5. If you were going to do this project again, are there any things you would you do differently the next time?
If I were to do this project again, I would get more replicates of the full experiment.  
6. Did working on this project give you any ideas for other projects? 
Working on this project gave me many ideas about new questions I would like to pursue. In fact, the entire point of this project was to gain ideas for other projects, which worked really well. The original idea was to just see what anomalies we could find, and then from there test those anomalies to find potential causes for the issues with phage therapy. This project hasn’t only given me more ideas for projects in antibiotics, but also in microbiology in general, as I now have the skills and knowledge needed to pursue further research. 
7. How did COVID-19 affect the completion of your project?
COVID-19 made it harder to collaborate with others, but as this was mostly just done in lab after COVID, that wasn’t as much of an issue.
Research Plan:
Hypothesis/Purpose (250)
We are currently undergoing an antimicrobial resistance (AMR) crisis, in which bacteria are becoming increasingly resistant to existing antibiotics. One approach to combat the AMR crisis is to use phage, which are viruses that kill bacteria. Unfortunately, phage therapy has not been successful in trials. To help better understand phage therapy, I sought to study the dynamics of phage infections of bacteria over time using quantitative methods.