Science Buddies: "Ask an Expert"

Hi,

I think I was posting my reply about the same time as Jane C and I think she has made some suggestions that should be helpful for you. It is not possible to always make definitive conclusions about every experiment, but hopefully results will give some clues about what the next experiment should be. You may want to consider continuing with this project next year; I'm sure you would be able to obtain some conclusive results with a few modifications to your experimental protocol.

I did not comment on the benzophenone question. This is a sunscreen ingredient and I could not find any information to indicate that it has significant antimicrobial properties. Whenever you test products that contain a mixture of ingredients, your results are the due to the combination of components and it is not possible to make a conclusion about a single component.

Donna Hardy

Yea, I understand what you are saying. I will definitely mention the points you made in my discussion because it is suppose to be about 2 paragraphs in length.

I really look forward to next year to experiment further!

An actual scientist runs tests HUNDREDS or THOUSANDS of times. This in comparison is preliminary results

And @Jane C. I know what you mean.

I'm the class dictionary.

I took the ISEE for private school and I walked around with 12th grade words on index cards for a weeks. The teachers didn't even know what most of them meant!

EDIT: What is better for a title, the problem or something catchy -ish?

For instance: "The Science of Less is More" or "Can You Actually Do More With Less" -something like that..

I think you should just use your problem as your title for your project. Btw, I am a little confused about your project. Are you following the original sciencebuddies.com project, where you test how different dilutions affect the development of bacterial resistance? Or are you testing how different dilutions affect the number of bacterial colonies?

If it is the latter, which I am sensing it is, I think your title should simply be: "How do different dilutions of disinfectants affect bacteria?" That is short (in my opinion) and to the point. I was always advised to use the problem as the project title, because the reader will immediately know what you are trying to solve. A "creative" title will often be ambiguous and vague.

I decided its better with the number of colonies.

"Do Different Dilutions of Disinfectants Affect the Inhibition of Bacterial Growth?"

This is my first year writing a background report paper. It's suppose to be one page in length.

Any advice? What should I discuss?

In order to be conservative and save space, I think your problem/title should be "Do different dilutions of disinfectants affect bacterial growth?" <--If I were doing your project, I would use that title.

I am posting what I have for my discussion so far.

After analyzing my results, I found that my hypothesis was could neither be found valid nor be condemned from the outcomes of my experiment. My belief applied to the products of mouthwash and all purpose household cleaner, however did not coincide with the outcomes for the products of soap and anti-acne. The soap and anti-acne products had bacteria greatly destroyed at the concentration level of 25%. There are a few factors that could have contributed to the nature of my results. For instance, the disinfectants were finished products or compounds, meaning they contained numerous substances –some active and other inactive. Having many substances in one solution and their interactions with each other could have influenced my results by either promoting or inhibiting bacterial growth. In addition, I worked with a mixed culture source of unknown bacteria, not a single bacterium, in an unknown phase of growth, which could have also led to my inconclusive results by adding another variable. Furthermore, I didn’t observe any growth during the first few days of the experiment, thus the chemicals in the disinfectants could have deteriorated – such as the alcohol in the anti-acne product. Although, after acutely looking through my observations and researching I came to a considerable conclusion that the more diluted a disinfectant is the more bacteria it inhibits, an actual scientist would repeat the results hundreds of times before coming to a final conclusion.
I was fond of this experiment because I had never studied microbiology, thus I took it as an opportunity to study a new area of science. Also, my results uncovered a truth which I would have never thought of otherwise or conceived before commencing the research involved in this project. I would most definitely recommend this project to others based on those aspects and for them to build off from my experimental findings to come to a more precise conclusion. In the future, I would personally want to compile more information regarding this topic by repeating this very experiment numerous times. In addition, I would like to branch off into more specific areas and bring it to the next level by either testing individual substances (such as alcohol or salicylic acid) against bacterial growth or single strains of bacteria instead of mixed cultures. I feel this is a significant subject matter due to the fact that many people employ large concentrations of harmful substances found in disinfectants in hopes of destroying all of the bacteria in their home. Using the outcome of this experiment, hopefully, they could realize that by using the principle of less is more, they can actually achieve more and keep their safety in mind. All in all, I enjoyed this subject and the studies regarding it and hope to do more regarding this in the time to come.


Comments? Ideas?

It's a very good discussion. What font and size will you be using for the discussion? I am slightly worried that it may be too long.

Hi,

Your discussion is excellent and very comprehensive. It should demonstrate to the judges that you understand the science behind your project have thought about your experiment. Jane's comment is a good one, however, and if you may want to consider writing a two-sentence summary of the results in a large font to put directly under your title so that most people looking at your project will understand from the title and the summary what happened. The science fair judges will not mind reading through the details of your analysis, but do make sure the font size is large enough to read for 2-3 feet away.

Is your one-page background report supposed to be a summary of the entire project, or a summary of the background reading you did before you started your project. Check the assignment that your teacher gave you. Here is information that includes an example for writing an abstract for a science fair project.

http://www.societyforscience.org/docume ... ,12,Sample Abstract

Donna Hardy

My title is " Do Different Dilutions of Disinfectants Affect Bacterial Growth?"

If I have space, ( I have a lot of information and pictures already to put on the board), I will add a two sentence summary. What should it include? Any suggestions? on that? Is it really necessary that I put one, or do you think it would not matter? I'm a little tight on space.

For the background, when I consulted her she's said "Oh, you could just talk about bacteria and purell and what kills it.." I'm not sure if she understood my project during our few minute conversations.

I was planning on breaking it into sections maybe? Maybe an introduction to bacteria and then break off to talk a little about each disinfectant?

Also remember those two sentences.. "This occurred because the lower concentrations are more effective in disrupting the cell membrane. However, that was not the case for the soap and anti-acne product – for them, most bacteria was destroyed at the level of 25%."

Can I leave them in the conclusion because I forgot to mention it in my discussion and my discussion is already loaded. Does it really matter?

Include the part about the disruption of the cell membrane in your report. If you must, include However, that was not the case for the soap and anti-acne product – for them, most bacteria was destroyed at the level of 25%. in your conclusion. If you are tight on space, I don't think you should include the two sentence summary. Remember that you need space for the information to "breathe."

Were you planning to break your report into sections? If so, I don't think that would be necessary unless your teacher said so.

What font and font size did you use for your project?

For the board I haven't quite decided yet - I'll put stuff up tomorrow. I think about 16-20 will be okay in Calibri. The report is 12 font in Times New Roman font. I asked her today and she said the report is basically background information or research before the project. I'm just thinking what key points I should mention in the report..Bacteria? Disninfectants? Something about the cell membrane and why it happened? Or a mix of all three?

I personally think a mix is good.

I finished my report, which is the last component of the science fair project! Tomorrow I shall look over everything for grammar and put it up on the board


My experiment surrounded bacterial growth and the effect different dilutions of disinfectants places on its. Firstly, bacteria are microscopic, unicellular organisms that are ubiquitous in each and every habitat on Earth. The earth is believed to have roughly five nonillion bacteria, which thus a considerable portion of the world’s biomass. They primarily live on the surfaces of objects where they can grow as colonies. Bacterial colonies are clusters of bacteria derived from single strain of bacteria. In order to analyze and examine the results of my experiment, I calculated the number of bacterial colonies in each section of the agar plates, which are petri dishes that contain growth mediums (known as agar) to culture microorganisms. Bacteria, as mentioned earlier, are found almost everywhere on our planet and subsequently also play in an important role in the lives of humans in not only negative, but also positive ways. Bacteria is mostly known and credited for its pathogenic species by the human race and the useful species are overlooked, which without their presence life may not be possible. They are vital in digesting food, making soil, degrading pollutants, and controlling insects. As bacteria can be found in many household surfaces, for the purposes of my experiment I swabbed a door knob from the entrance to my home. Although, it is ambiguous what exact species were used, I am aware that the most common types of bacteria on door handles are staphylococcus, streptococcus, e-coli, salmonella, and campylobacter.
For the functions of this project, I used four different kinds of disinfectants – all purpose household cleaner, an anti-acne product, mouthwash, and a soap product. Each of these disinfectants contained active ingredients (generally cleaning agents that have antimicrobial properties) and inactive ingredients (substances add to maintain or add fragrance to the product or even aid the cleaning agent). In my case, both types of these substances could have interacted with each other in a manner that could have affected or caused a slight inaccuracy in my results. Fabuloso, the all purpose household cleaner, contains sodium dodecyl benzene sulfonate, C9 – 11 pareth-8, and sodium laureth sulfate as its cleaning agents. Clean & Clear Deep Cleaning Astringent comprises of salicylic acid 2.0% and 24.5% of alcohol for its active ingredients. Additionally, Scope Antibacterial Mouthwash has approximately 15% of alcohol, cetylpyridinium chloride, and domiphen bromide for its active ingredient Furthermore, Lucky Super Soft Antibacterial Hand Soap consists only of one active ingredient -0.1% of triclosan.
After I performed the experiment, I came to the conclusion that in terms of destroying bacteria, you can eradicate more bacteria with a more diluted solution of disinfectants, or in other words you may actually to be able to do more with less. However, this is a finding that can alter depending on which compounds you are testing and the bacteria that is being test on. Every species of bacteria has its own growth rate and different resistance to certain compounds, which can affect your results. Based on research that I have completed, I believe that the higher concentrations of disinfectants can form a hardened protein wall around the outside of the organism, rather than permeating into the cell and destroying it. This shell will lead it to become dormant, but after some time and under certain conditions the bacteria may have a revival. Nonetheless, the lower concentrations of, more diluted disinfectants are able to seep into the cell membrane of the bacteria and slow down or destroy the microorganism altogether.

Comments? Suggestions?

Hi,

You’ve done a very good job in presenting background information and summarizing the results of your project. You can consider the following suggestions if you would like.

1. Rewrite the first sentence to state the objective of your project, e.g. “I investigated the effect a different dilutions of antimicrobial agents on bacterial growth.”

2. Clearly state your hypothesis.

3. For every statement you have made based on literature references, include a citation. For example, the statement about the number of bacteria in the world, add a number at the end of the sentence and a footnote if you have one available.

4. In your conclusion paragraph, instead of saying, “I came to the conclusion.” summarize your data and state what your data actually showed. Then compare your results with your hypothesis.

5. In stating the reason for your results, instead of saying, “I believe. . . .” use a reference from scientific literature that supports your statement.

6. Recheck the written assignment from your teacher, and make sure you have included everything that is required.

I hope this helps.

Donna Hardy

Thank you so much! I will add the suggestions in now. The due date for my project was shifted to Thursday

Hi,

Good you have 2 more days. I was hesitant to send the suggestions because I knew you were at deadline, and your project would have complete at it was. However, incorporating the changes I have suggested will help the science fair judges understand the project.

Good luck!

Donna Hardy

Hi,

I'm sorry I haven't been as active on the forums this week as I'd like to be. I've been having so much work at school, and I was away for the New Years. Good luck on your presentation tomorrow! I'm curious to know what your grade is on the project, and maybe even what place you won in your school fair! So please, keep us posted!

Best regards,
Jane

I presented yesterday.. I think I got a 98.

However, I dont think shes sending me to the fair. Someone did a similar topic to me, and I think she happened to like his better........

Oh wells . I won first place last year with a project on Enzymes affect on Glucose Concentration..

I'm sure you still did a great job It's okay that you didn't get into the fair; 98 is still an excellent score!

Do you happen to know why your teacher took off 2 points?

I'm not sure because a kid sitting next to her said he saw her put 98 in her grade book next to my name. When I get my rubric back, I'll let you know

It turns out that....I got a 100 for the grade ...and.. I went to the fair! I won 3rd place. I think thats pretty good considering how I was lost about how to do this project for much of it.

Uhm, I got my bacteria back... The only thing is that.. How do i get rid of it? Its like overgrown now.

Hi,

Congratulations on getting a 100 and winning third place in the science fair! To properly dispose of the bacteria, according to the Sciencebuddies.com website, you should follow this procedure:

Safe Disposal of Plates

At the conclusion of the experiment, all plates should be disinfected for safe disposal.

The best way to dispose of bacterial cultures is to pressure-sterilize (autoclave) them in a heat-stable biohazard bag.
If autoclaves or pressure cookers are not available, an alternative is to bleach the plates.

Wear proper safety equipment (gloves, lab coat, eye protection) when working with the bleach solution; it is corrosive.
Saturate the plates with a 20% household bleach solution (in other words, one part bleach and four parts water).
Allow the plates to soak overnight in the bleach solution before disposing of them.
Please note that the bleach solution is corrosive and needs to be thoroughly rinsed afterwards.

If, for some reason, you can't or don't want to wait overnight before getting rid of your plates and want to dispose of them immediately, I think that it would be fine if you just use a household spray cleaner with bleach in it. An example of this would be the Clorox Clean-Up Cleaner with Bleach (http://www.clorox.com/products/clorox-clean-up-cleaner/)

Btw, now that you've won in your school fair, do you go on to regional/district-wide fairs? I know some schools do that and some just end it at the school level.

No, it just ends here.

The thing is I'm scared to open the bacteria. My science teacher was clueless and just suggested I throw it as is.

Well if you really want to take protective measures, then wear gloves and a face mask, and try not to breathe that much when you're spraying or pouring bleach on the agar. Also spray or pour the bleach in a well-ventilated area with all the windows open, because bleach has an unfriendly aroma. You definitely shouldn't throw it out as is, because the bacteria will continue growing. If you accidentally grew pathogenic bacteria, it might even contaminate into your trash can.

is there anything I can do to just like freeze the growth?...

Not that I know of. I think your best option to do would be to spray/pour bleach onto the agar.