Science Buddies: "Ask an Expert"

Hi Irregular,

Your results are very interesting. There are some references showing that glucose can be used in MFC's, but most references show that acetate works the best in MFC's. However, your results are empirical. This means that your results are actually what happened; you have actually measured the results, so they must be real and you just need to explain them. What was the concentration of glucose that you used? Was it a higher molar concentration compared to the acetate?

The explanation for your conclusion section of your paper and board, assuming you can say that all other conditions were equivalent, it that the specific bacteria growing in your mud sample were able to metabolize the glucose more efficiently compared to acetate. The numbers of electrons produced is directly related to the production of energy by growing bacteria, so you have shown that glucose is a better energy source for your MFC. This is excellent because you have a definite result, and you can make a definite conclusion and explain it.

Are you finishing up your board and research paper? You have done a lot of work on this project and I think it is turning out really well, in spite of the high resistance.


Donna Hardy

Hi Donna!Sorry for responding late!

(I used 10ml of vinegar and sugar each in the same amount of pond water+mud mixture, so it was a controlled variable)
So the graphs are finished, display board has been purchased, experiments have been stopped. I re-did the acetate experiment and received higher power outputs. Three graphs have been made with 3 sets of data on each - the comparison of Current and Voltage, Current and Time and Power (Watts) and Time. Acetate and Glucose had high measurements.

I am finalizing my entire final report by tonight, including the abstract, results, etc. I will be researching
1) possible reasons why glucose was as effective/more effective as/than acetic acid
2) why i had a power output with no added substrate

While my report is being edited, I will transfer the information for the display board, print them out, and organize them on the board.

Thanks so much!

Hi Irregular,

You are very smart to stop and leave yourself time to write up your board. This is going to be an impressive project.

Your glucose result is your dependent variable in this project and the results are empirical. In other words, the higher power output with glucose is what actually happened in your carefully controlled experiment. Based on the literature search, you were expecting higher results with acetate, but the mixture of organisms in the mud you collected was able to metabolize glucose better than acetate. You don’t actually have to explain this, but you might say that finding the answer would be a subject of a future investigation in next year’s science fair project.

You had power output with no added substrate because there was undigested organic material in the mud that you collected that the bacteria were able to utilize. The bacteria were probably not growing very fast in the frozen lake, but they were able to revive and start metabolizing again in the warmer furnace room. The no substrate added sample acted as your control or baseline level to compare results with added substrates.

You should also include a discussion about high resistance in your MFC, apparently due to the salt bridge. You can mention in your discussion section that one of the problems reported in the literature for MFC’s is high resistance, and you also experienced this problem.

If you are interested in continuing this project, I think it would be an excellent idea to continue experiments over the summer. Maybe you could use a different design that would give lower resistance. The bacteria would grow much better in the warmer temperatures, and your results could be spectacular.

Let us know if you have any questions.


Donna Hardy

Hi Donna!

Thanks so much, especially to explaining to me why there was electricity generation when no substrate was added!

I have a few things in mind to add in the discussion, and high resistance was definitely one of them.

I would definitely love to continue this experiment!

Okay, so the final report and graphs are all complete! My dad has a laser printer at work and will come back today with the printouts. We are keeping extra printouts of the reports in case judges would like a copy. I am hoping that my report and/or display board pages are proper and do not contain any mistake... Since tomorrow is a holiday, I hope that I will be able to setup the display board and everything. Starting this weekend, I will read and 'study' my information, and then create some short speeches for the judges. One week left until the science fair!

Thanks so much, Donna! You've helped me from start to finish - I don't know how I could ever appreciate you enough!

Congrats on finishing your project! let us know how the science fair goes.

You probably already know about these pages, but I thought I'd remind you of them:

Judging tips (regular): https://www.sciencebuddies.org/science- ... ging.shtml

Judging tips (advanced -- keep in mind that these are geared towards high school students): https://www.sciencebuddies.org/science- ... tips.shtml

Hi Amber!

Thank you very much! I had previously printed out a copy, and am working on writing and practicing my short speech. The science fair is getting closer and closer!

Thanks!

Hi!

Quick question: are ionic and/or covalent bonds significant in my project? If yes, how?

I read a little bit about them while searching electronegativity, and was curious.. Thanks!

Two more days until the fair!

Hi Irregular,

The difference between ionic and covalent bonds is not significant for your project. Your project had so many important scientific topics, so it's nice that you don't have to worry about one.

Good luck at the fair! Be sure to let us know what happens.


Donna Hardy

Hi Donna!

Oh my, how can I thank you ever so much?! You, along with a few other experts here at Science Buddies, helped me sooo much. You were there from the beginning, encouraging me and giving me tips. You helped me formulate my hypothesis and edit my report, and gave me advice and ways to troubleshoot problems which occurred. Thanks, I'll never forget the amount of help you gave me.

I am so very thankful - I will be moving onto the next level, along with 4 other students, to the CWSF! It feels so amazing - all my hard work paid off, and it's only my first year to qualify, and I made it! Along with that, I got a best in my Earth and Environmental Junior Division category, and a about 3-4 other awards.

We will be provided with big display boards, so I will be able to enhance my project.

The judging period: It went well, though it took me some extra time to explain what a MFC is and how it exactly works. Here are three very good questions. Note that the last two were asked by the same person. I might've not answered them properly, but they gave me a prestigious award from their company.:

1) (This judge had judged me last year as well, and he is known to me by asking hard and challenging questions. His questions really make me think.) You made a big assumption in your hypothesis and conculsions. You stated that it'll be easier for bacteria to break down acetic acid, 2 carbons and glucose, 2 carbons. You also stated that you predicted that glucose was promising (in your conclusions) because the there were 12 hydrogen atoms, and only 4 in acetic acid. You must know that the bonding between atoms and their energy can be different. Some bonds are so strong that it cannot even be broken down.
2) (i specifically wrote this down in my lab notebook to remember) Another byproduct of respiration is methane gas. How does this effect the MFC, and is it harmful? Is the amount of methane more than the amount of carbon dioxide produced? (i found a link relating to my question: http://www.microbialfuelcell.org/www/in ... a-MFC.html)
3) In the chemical reaction, carbon dioxide is produced. Releasing a lot of carbon dioxide eventually may harm the environment and could affect greenhouse gases. How would you deal with this and dispose the carbon dioxide?

Thanks!

Hi Irregular,

Congratulations! I am so happy that all of your hard work paid off with such a spectacular win. Best in category plus other awards. This is absolutely fantastic!!! And, going to the CWSF will be such a wonderful experience for you.

You can use the questions that the judge asked you to help you prepare the large board for the CWSF. He asked excellent questions and you can be prepared to answer these questions and more at the next level. Here is a brief answer to the questions.

You had expected the bacteria in your MFC to metabolize acetic acid best because almost all of the papers you found on this subject reported that acetate was the best carbon source. This was not just an assumption on your part; it was based on the scientific literature. There was one very early paper that reported an organism that was able to utilize glucose, but that was an exception. Here is another paper that reports using glucose for an MFC, but the authors did not use acetate.

http://www.enotes.com/microbiology-ency ... oorganisms

The metabolism of the anaerobic bacteria is part of the carbon cycle:

http://www.enotes.com/microbiology-ency ... oorganisms

Plants capture carbon dioxide and convert it to sugar. Aerobic organisms metabolize the sugar back to carbon dioxide. Anaerobic bacteria metabolize sugar to acetate and then to methane. The methane can be converted back to carbon dioxide by aerobic microorganisms. The carbon cycle is very pertinent to your topic, although the MFC bacteria are participating in a very small part of the carbon cycle, so you could do more background reading on this subject in preparation for the next level of competition.

In an MFC, the conditions are hopefully optimized so that bacteria will use the carbon source and produce electrons, which are capture by the anode electrode. Methanogenic bacteria are undesirable in an MFC because they use the carbon source and do not contribute much to the production of electricity. However, did you see any bubbles forming in the anode chamber of your MFC? If you did, this was probably methane gas. If you did not see any bubbles, then your MFC probably did not contain methanogens and conditions were optimum for power production. You could add these observations and the significance of bubbles since you will have more room on the large board.

Before you start revising your board, I recommend that you go back and read all of the references you have accumulated again and see if this will give you more insight into your project and your results. I also suggest that you lay out your board and plan the content in each section of the board. The science fair judges at CWSF are going to be seeing other excellent projects, so you will want your presentation to be very clear and organized. You will have room to add more visuals and also more detailed analysis of the results.

Let me know if you have any more questions.

Donna Hardy

Hi Donna!

Thanks so much! I'm REALLY looking forward to the experience and am sure that it will be a rewarding one. Gosh, I'm so thankful!

1. Okay, yes, thanks for reminding me about the scientific literature! I think that it sounded as if the judge was hinting that I should have seen which atom bondings in acetic acid and glucose are breakable, and which ones are so strong that they cannot break. He also mentioned that I should have looked at the energy of the bonds.

2. I answered this question and mentioned how plants can use carbon dioxide. I will definitely do some research on the carbon cycle. The resource you provided me with is amazing, thanks! Questions on the cycle:
So when the carbon dioxide is converted to sugar, where is the sugar stored? Inside the plant? So then how does the anaerobic bacteria (Methanogenic bacteria) access the sugar?
Where is the sugar which the bacteria metabolize in a MFC?
I will do more research to try to answer these questions of mine myself as well.

3. No, I did not see any bubbles in the anode. This is a very interesting thing I will definitely add this to my board! However, you mention that Methanogenic bacteria do not help very much in a MFC. The reference you gave me says that they do help in yielding energy and water, so I'm assuming that they do, but a small quantity... Which section of my board and report should I add this to? My experimentation? Results? Research?

4. My results:
Currently, my results + conclusions include:
a) Acetic acid shows to be more promising for running in larger periods of time, since glucose showed a quick increase, peak, and a quick decrease, while acetic acid mounted, peaked and decreased relatively slowly.
b) My hypothesis proved wrong, in a way, because I thought that glucose would be much less promising than acetic acid, since it has a lot of carbon atoms. Yet glucose showed the highest power output, at one point in time. I predicted that this happened because glucose has 12 hydrogen atoms, while acetic acid has only 4. So, in the same quantity, much more hydrogen is present in glucose. Yet, power outputs probably decreased quickly because bacteria got worn out by breaking down so many carbon atoms.
c) I had power outputs when I added no substrate because of organic compounds already in the mud, which served as a substrate. In the optimum environment in my warm furnace room, bacteria started metabolizing again and used these compounds as a substrate.
d) How my experiment was a fair test
e) What I would do next time

(Each lettered information has it's own paragraph)

How do you suggest I improve this section, or to make it more detailed, as you said, to impress the judges?

5. To finish registration, an online copy of my report has to be sent. I will tweak it up by correcting any possible mistakes in it. Something I am concerned about is the length of my research section and glossary. It is pretty lengthy, the research section on MFCs (how it works, applications, types of MFCs, etc) takes up about 11 pages. My glossary takes 9 pages. My entire report totals up to about 44 pages. Should I leave it how it is?

Using a bigger display board will mean my board looking visually appealing. It is recommended I get the board laminated. Do you think I should stick to the paper on top of coloured paper design, or go for the more professional printing everything out on a big paper the size of my board? There is a shop where I know where the second option can get done. I am just a little concerned about the money which will need to be spent on that, and if it'll be worth it.

Thanks so much, Donna! It's like the science fair all over again! I'm so happy to be able to make this project more advanced!

EDIT: IMPORTANT INFORMATION: The CWSF is asking if I had a mentor. It asks a) whether I had one b)amount of communication c) who the mentor was d) how I found my mentor. In my situation, I would cross out the "not having a mentor" choice because I certainly did have a mentor. So I can either list you or my father as my mentor. Both of you helped me in the project, were extremely knowledgeable and helpful, and are people I am VERY thankful for. Which do you recommend I choose? Only one answer is permitted.

The registration also asked me whether I dealt with pathogenic microorganisms. Should I state yes or no? In my case, I was not able to identify whether bacteria was pathogenic or not... I will look to finding out if I can display my MFC with bacteria inside, since in my regional fair I showed the MFC without anything inside.

Congrats irregular!

They asked you some very tough questions. I'm actually very surprised they asked you those questions since you are in middle school, though I guess they thought you could handle it since you had such an advanced project .

Good luck with the next competition!

hi irregular,
i just remembered corresponding with you a while back, and checked out this thread - congrats! good luck at cwsf!

Hi guys!

Thanks so much! I really appreciate it, and me too I wish that I will be able to be successful at CWSF. Amber, I was surprised as well, but at CWSF I guess they will be asking tougher questions. I'm currently carrying out some additional research. You must know the feeling Amber - happiness, excitement.. and, for me at least, some sort of nervousness.

AN UPDATE FOR DONNA:

1) I am currently learning about the chemical bonds.. I learned about ionic bonds, covalent bonds, metallic bonds, Van der Waals forces, covalent networks, ionization energy, etc. I am going to do a little research to clear up some confusion of mine, which is how oxidation and ionization energy are different.

2) I will start to study about the carbon cycle tonight. My original questions:

irregular wrote:So when the carbon dioxide is converted to sugar, where is the sugar stored? Inside the plant? So then how does the anaerobic bacteria (Methanogenic bacteria) access the sugar?
Where is the sugar which the bacteria metabolize in a MFC?

3) I will also research methanogenic bacteria.

irregular wrote:The reference you gave me says that they do help in yielding energy and water, so I'm assuming that they do, but a small quantity... Which section of my board and report should I add this to? My experimentation? Results? Research?

4)

irregular wrote:My results:
Currently, my results + conclusions include:
a) Acetic acid shows to be more promising for running in larger periods of time, since glucose showed a quick increase, peak, and a quick decrease, while acetic acid mounted, peaked and decreased relatively slowly.
b) My hypothesis proved wrong, in a way, because I thought that glucose would be much less promising than acetic acid, since it has a lot of carbon atoms. Yet glucose showed the highest power output, at one point in time. I predicted that this happened because glucose has 12 hydrogen atoms, while acetic acid has only 4. So, in the same quantity, much more hydrogen is present in glucose. Yet, power outputs probably decreased quickly because bacteria got worn out by breaking down so many carbon atoms.
c) I had power outputs when I added no substrate because of organic compounds already in the mud, which served as a substrate. In the optimum environment in my warm furnace room, bacteria started metabolizing again and used these compounds as a substrate.
d) How my experiment was a fair test
e) What I would do next time

5) This problem has been solved. The report must be 5 pages, and I will cut down the glossary completely, and provide it in a duotang at my display board. I will cut down my original report down to 5 pages and send that, but provide my 5-page one AND the original one just in case, for more details. The report is 10% of my marks!

6) My display board problem is also solved. I will be probably printing everything onto one paper, I will use a program similar to Photoshop and there is a local printing shop I can go to.

7)

irregular wrote:EDIT: IMPORTANT INFORMATION: The CWSF is asking if I had a mentor. It asks a) whether I had one b)amount of communication c) who the mentor was d) how I found my mentor. In my situation, I would cross out the "not having a mentor" choice because I certainly did have a mentor. So I can either list you or my father as my mentor. Both of you helped me in the project, were extremely knowledgeable and helpful, and are people I am VERY thankful for. Which do you recommend I choose? Only one answer is permitted.

The registration also asked me whether I dealt with pathogenic microorganisms. Should I state yes or no? In my case, I was not able to identify whether bacteria was pathogenic or not... I will look to finding out if I can display my MFC with bacteria inside, since in my regional fair I showed the MFC without anything inside.

Please note that the next month will be extremely busy for me, as I have very important school projects, big tests, musical examinations coming up, and the science fair. Feel free to leave a reply, but note my response might be late, ranging from maybe 1 to 3 weeks- just a warning. Thanks so much Donna, my project wouldn't have been successful at my regional fair without your help!

Hi Irregular,

You are making so much progress. I am so sorry, but I'm short of time today, so I will have to plan to answer all of your chemistry questions tomorrow.

For the CWSF forms you need to fill out, I recommend putting down sciencebuddies (https://www.sciencebuddies.org) as your mentor. However, you could not have done the project without your father's help, so on your board, add an acknowledgement for your father's contribution. He deserves credit for all of his hard work in taking you to the frozen lake and the electronics store, and everything else.

Donna

Thank you!

Thanks for answering the mentoring question. Acknowledgments are not allowed on the board so I will alternatively somehow provide my acknowledgments.

UPDATE:

1) I learned about ionic bonds, covalent bonds, metallic bonds, Van der Waals forces, covalent networks, ionization energy, etc. I just have to study what I learned to make sure I understand them.

2) I will start to study about the carbon cycle tonight. My original questions:

irregular wrote:So when the carbon dioxide is converted to sugar, where is the sugar stored? Inside the plant? So then how does the anaerobic bacteria (Methanogenic bacteria) access the sugar?
Where is the sugar which the bacteria metabolize in a MFC?



3) I will also research methanogenic bacteria.

irregular wrote:The reference you gave me says that they do help in yielding energy and water, so I'm assuming that they do, but a small quantity... Which section of my board and report should I add this to? My experimentation? Results? Research?


4) How should I make my results better? Each letter has it's own paragraph.

irregular wrote:My results:
Currently, my results + conclusions include:
a) Acetic acid shows to be more promising for running in larger periods of time, since glucose showed a quick increase, peak, and a quick decrease, while acetic acid mounted, peaked and decreased relatively slowly.
b) My hypothesis proved wrong, in a way, because I thought that glucose would be much less promising than acetic acid, since it has a lot of carbon atoms. Yet glucose showed the highest power output, at one point in time. I predicted that this happened because glucose has 12 hydrogen atoms, while acetic acid has only 4. So, in the same quantity, much more hydrogen is present in glucose. Yet, power outputs probably decreased quickly because bacteria got worn out by breaking down so many carbon atoms.
c) I had power outputs when I added no substrate because of organic compounds already in the mud, which served as a substrate. In the optimum environment in my warm furnace room, bacteria started metabolizing again and used these compounds as a substrate.
d) How my experiment was a fair test
e) What I would do next time


7)

irregular wrote:EDIT: IMPORTANT INFORMATION: The registration also asked me whether I dealt with pathogenic microorganisms. Should I state yes or no? In my case, I was not able to identify whether bacteria was pathogenic or not... I will look to finding out if I can display my MFC with bacteria inside, since in my regional fair I showed the MFC without anything inside.


Please note that the next month will be extremely busy for me, as I have very important school projects, big tests, musical examinations coming up, and the science fair. Feel free to leave a reply, but note my response might be late, ranging from maybe 1 to 3 weeks- just a warning. Thanks so much Donna, my project wouldn't have been successful at my regional fair without your help!

Hi Donna!

My project is going well. I had to shift away from my science fair project for a few days due to a major school project, but now I'm back on track.

Okay, so by tonight-tomorrow I am planning on finishing the understanding of my research. Then, this weekend, I will opt to finish my display board, and get my board laminated. For the next week, I will review my project and practice, until my depart. Some questions I have:

1) I studied chemical bonding and found out the energy of certain bonds in acetic acid and glucose. I would like to compare the energy needed to break down a bond with the energy that bacteria produces. This way, I could see if bacteria is able to break down the bond at an efficient speed. I am on the search to find sources which will tell me the amount of energy bacteria produce during anaerobic respiration. So far, I haven't found one which tells me exactly or approximately how much energy bacteria produces. It would be greatly appreciated if you could help me.

2) Do you think it is worthy that I edit anything I wrote on my display board? I hope that my information isn't too simplistic for CWSF.

3) The report CWSF asks you to write is a 5 page report, which i have already written and sent. My report for my regional fair was much more than that (I shortened that in order to write my CWSF report). I will be taking out my research and glossary section of my original report (to put on my table). At my table, should I offer the concise report I wrote for CWSF, or my original report from my regional fair which is more detailed (minus the glossary and research section, which will be available in a separate duotang)?

4) I have studied anaerobic respiration, do I need to study fermentation?

Thank you so much!

Hi Irregular,

It’s nice to hear from you again. I’m glad you survived your other school projects. Hopefully the science fair will be your last major project for the year.

Here are some comments that should help you; I have tried to modify the explanation as it applies to your microbial fuel cell:

If you have studied the chemical bonding of glucose and acetate, you know that there is energy trapped in the covalent bonds between the carbon atoms that can be released when the molecules are metabolized. The energy currency for all living organisms is ATP, or adenosine triphosphate. The amount of energy released by aerobic metabolism of one molecule of glucose is 38 to 38 molecules of ATP. Anaerobic metabolism of glucose will yield up to 4 molecules of ATP, depending on the pathway and anaerobic metabolism of acetate will yield 1 molecule of ATP.

Aerobic metabolism is obviously much more efficient, but anaerobic bacteria are occupying a specialized environmental niche and they are able to grow in environments where the aerobic organisms cannot grow. Acetate is a very common byproduct of microbial metabolism so many anaerobic microorganisms can use it as an energy source, and even though not much ATP is produced, they are able to grow and survive.

In the microbial fuel cell, the metabolism of the microorganisms is proportional to the production of electrons. The bacteria are using the glucose/acetate for energy and the byproduct is electrons are transferred to the anode electrode.

Here are some references that will give you more background information. I have posted the first reference before, but it contains the best summary of bacterial respiration/fermentation in a microbial fuel cell. Please note that even this summary states that not everything is understood about the metabolism of bacteria in an MFC, and, if asked by a science fair judge about this, you might want to say that this could be a topic of a future science fair project:

http://www.microbialfuelcell.org/www/in ... nisms.html


http://books.google.com/books?id=cXnc2w ... &q&f=false

http://aem.asm.org/cgi/reprint/55/2/514.pdf


2. Can you upload a copy of the text from your board? If not, then have someone who has not seen it look at it and make sure the presentation is very clear and straightforward. Make sure you have an abstract that describes the project and the result in 2-3 sentences. You definitely don’t want to make the presentation more complicated than necessary. The judges will be interested in knowing if you understand the science behind the project and the design of the experiment, and your analysis of the results.

Look at your project and decide if there is anything (pictures or diagrams) that would help make your project more understandable to someone looking at your board.

3. Since you are not limited in what you can include on the display table, I would put out your more detailed original report. The 5-page summary report will probably be used for preliminary judging or perhaps for preparing abstracts of the show.

4. You should be familiar with the basic definitions of fermentation and respiration:

http://en.wikipedia.org/wiki/Fermentati ... chemistry)
http://en.wikipedia.org/wiki/Respiration






Donna Hardy

Hi Donna!

1)Okay, so anaerobic metabolism of glucose gives 4 molecules of ATP, and anaerobic metabolism of acetic acid gives 1 molecules of ATP. That is another thing which I could explain in my conclusions section (why my hypothesis was wrong). I found a source which gave me the a) length and b) energy in bonds of certain elements (http://en.wikipedia.org/wiki/Chemical_b ... ical_bonds). Instead of giving me information of energy in ATP, this gives me energy in kJ per molecule. Is it possible to convert kJ to ATP? If I can convert this, then I will be able to see if all bonds can be broken by bacteria. I know that anaerobic metabolism of glucose gives me 4 ATP molecules now, then for example I need to know how much energy a double carbon bond has, in ATP ( it is 614 kJ/molecule)

2) If I understand correctly, a byproduct of anaerobic respiration may be acetic acid, if there are acetogens present in the mud sample. I should also do some reading on methanogens, specifically as well.

Thank you for the references on fermentation and respiration!

3) I will definitely upload the display board copy for you. I am planning on including a photo book, my long report, my CWSF report (the CWSF 5 page report I sent in is actually worth i think 10 or more marks of my entire project, out of 100!), a simple flowchart of my project, my glossary, references and an abstract on my table. Diagrams, pictures, graphs and text (text = background, purpose, hypothesis, methodology, results, conclusions, discussion, applications) will be on the board. I may have one picture of my MFC on the board, I will have a picture of a molecule of glucose, a picture of a molecule of acetic acid, and the MFC diagram by Rabaey and Verstraete on the board. I will see which other pictures would be effective on my board too.

4) I wanted to review my Discussion section. In that section, I talk about my salt bridge resistance problem which other scientists encountered too, how I would improve my project, and topics for further MFC research. What else do you recommend I include? You will be able to fully read my section once I upload my display board copy (I will send it tonight or tomorrow)

5)Lastly, I wanted to ask you what I can put on the "Background" section on my board, the research section. I was thinking about using that to explain the working of a MFC, but the CWSF preparation guide I am following discourages long runs of text such as descriptions and explanations, and says I should replace such with a diagram or flowchart (my MFC diagram borrowed from Rabaey and Verstraete will be present in the background section as well). I am unsure about this now. However, I still think it would be most effective to put on my board for the background section, out of all the parts of my research section - how an MFC works, types of MFCs, materials in MFCs, brief history of MFCs, the perspective of MFCs.

Thank you!

Hi Irregular,

You have excellent questions.

1. I’m not certain if there is a definite answer to your first question.

First, there is a certain amount of energy in a carbon-carbon bond, but when an organism breaks the bond, part of the energy is captured in the ATP molecule and part is released as heat. There is 347 kJ/mole in a single carbon bond. Microorganisms vary in their efficiency in converting the energy in the carbon-carbon bonds to usable ATP. To find out what was happening in your MFC, you would need to measure the actual result to know what the energy output was (this was definitely outside the scope of your project, but could be done in a future project).

http://academic.pgcc.edu/~ssinex/struc_ ... n_bond.htm

Also, there seems to be some variation values reported for Kjoul/mole of ATP. This site lists references that have reported values ranging from 29 to 63 kJ/mole of ATP.

http://hypertextbook.com/facts/2000/AmberIqbal.shtml

The Wikipedia website reports -50 kJ/mol-1, but doesn’t give a reference.

http://en.wikipedia.org/wiki/ATP_hydrolysis


2. Yes, under anaerobic conditions, some organisms break down glucose to acetic acid and some organisms break down acetic acid to methane and carbon dioxide. I will upload two pages that will give more information on this. The first is from a book and shows the pathway of glucose breakdown to form acetate. The second is from a reference that was studying the metabolism of microorganisms in wastewater that were fed acetate and propionate. The authors measured the ATP production to show that the microorganisms were actively growing when fed acetate and propionate. Unfortunately, these authors did not study what metabolites were formed from the breakdown on the acetate; they just measured the decrease in acetate and the formation of ATP.

3. The composition of your board sounds good. The combination of text and visuals should be very effective. I can hardly wait to see it.

4. You do not know the exact metabolic pathways of the bacteria that were growing in your MFC because this was outside the scope of your project, but studying this could be a future topic of study. I will think more about this question and try to give you more ideas.

5. Since the judges might not be familiar with an MFC, I think that background information on the history, purpose, and how it works might be useful. Since the guidelines you are following are discouraging you from too much text, you should be brief. Look at the first paragraph or two of some of the references we have seen to give you an idea of what you might say.

Donna Hardy

Hi Donna!

Since my display board is number one priority, I'd like to finish that off first. I have enclosed my display board copy with this post. I hope that it stays safe and no one else can get access to it, other than you and other experts! I know that this is a little rushed, but it would be appreciated if you could send back your comments by this afternoon, if not tonight. Note that the subtitles are there for organization - I will be removing them and using bigger WordArt subtitles. Please give me your comments on font, format, understandability, things to add/remove, etc. I'd like to print everything off tonight or tomorrow, and send it in for lamination tomorrow night. Note that after this is sent I will still be making changes to it (cutting down a few things, editing the sections), but I'll save it as a separate document.

1 and 2: Once the display board is finalized, I will thoroughly explore the research links and get back to you, since I'll have a better understanding. I have skimmed through them already.

Thanks so much!

Hi Irregular,

THanks. I am printing out the board now, and I will reply with my comments as soon as possible.

Since this is a public forum, accessible to anyone, since you are concerned about others seeing your board, you can edit your posting and remove the attachment.

Donna

Hi Donna!

I have removed the document from my previous post.

You will note that some parts of my display board copy (i.e. the background part) are directly from my report. Those are the sections that I am currently editing. Once I have finished my editing and once I receive your comments, I will adjust my copy. Then, if you would like I will send you the final copy so you can briefly revise it.

Thanks so much, you've helped me incredibly from the start to the end!

EDIT: You may have noticed some wrong information in the Background section, including the recombination of the electrons and protons in the cathode. Please ignore this, I will send you the correct information when I send you the final draft (as mentioned above).

Hi Irregular,

I enjoyed reading your presentation! After going through the project, step-by-step, I was very impressed at how well you have integrated all of the very complicated background information on this project and presented your essential results. You have done an excellent job!

Here are my comments section by section.

Background: Reword the first sentence to give your reader a one sentence summary of your entire project. Perhaps something like, “The production of electricity in a microbial fuel cell is based on the rate of metabolism of anaerobic bacteria growing on an organic carbon substrate.”

The equation is great because it shows where the electrons are coming from.

Perhaps change the sentence after the formula to:

“Therefore a 6- carbon sugar molecule will result in the production of 6 water and 6 carbon dioxide molecules as well as 48 protons and electrons. The transfer of some of the electrons from the actively growing anaerobic bacteria to the anode and then the cathode electrode results in the production of electricity in the MFC.”

Good description of the function of the mediator.

You need a brief description of the bacteria used in an MFC. Add a short paragraph which includes the following information. “The bacteria used in an MFC are mixed cultures of bacteria that have the ability to grow anaerobically, or in the absence of oxygen. The bacteria that work best in an MFC are present in mud samples found at the bottom of freshwater lakes and streams. Anaerobic respiration is not as efficient as aerobic respiration, so the bacteria obtain less energy, or ATP, per molecule of substrate.”

Next paragraph with the description of the function of the MFC. It would be helpful if you referred to a picture, for example, (see Figure 1) so the reader would be looking at a picture of the MFC while reading this paragraph. You can omit the sentence starting with “A load” since you did not actually use a load in your project. However, if you don’t need to reduce the number of words in your presentation, it’s perfectly OK to keep it in. After “salt bridge,” add “, which provides a barrier (or separates) the anaerobic anode and aerobic cathode chambers.” This helps explain the function of the salt bridge.

Replace some of your words in the next paragraph with another formula. Only 12 oxygen molecules are required for 48 electrons, since oxygen is always O2.

48 e- plus 48 H+ plus 12 O2 goes to (with an arrow) 24 H20.

History:

Add Bruce Logan from Penn State to the list of people who have contributed to the understanding of microbial fuel cells. Many of the references we found were coauthored by Dr. Logan:

http://www.engr.psu.edu/ce/enve/logan/b ... ch_mfc.htm

Purpose:

Add to the first sentence, “and to compare the electrical power generated by different growth substrates.”

Methodology

Add vinegar and glucose to your list of materials.

However, if you used table sugar, you used sucrose, which is a 12 carbon sugar composed of a molecule of glucose and fructose. If you used table sugar, you should change all of the “glucoses,” in you paper to “sucrose.” And, you need to change the number of carbons to 12 from 6 in the result and conclusion sections.

You captured the details of the leaking and high resistance perfectly!

Results.

This section is very good.

On the second table of results, did you get the exact same values for acetic acid and glucose (sucrose)? It seems like there is one set of results missing from the table.

Conclusion:

Great!

Discussion:

Future studies.

I like all of the topics you have listed.

You could also add that you would do experiments in the summer so you could use a higher temperature to encourage the bacteria to grow faster and therefore produce more power.

Bibliography. Where is your bibliography section? Are you including is separately. Your bibliography is actually one of the good features of your project because is shows that you did your background reading on the project.

Please let me know if you have any questions. I will check in later in the day.

Donna Hardy

Hi Donna!

Thank you so much for your comments! It's always great to have a fresh eye look over the project. My father and my brother edited the copy once again to shorten it up, etc. Please note that I had to cut out the history section, since I had a lot of text. I might have to shorten more things up, since the board is meant to be as aesthetically pleasing as possible. The display board is worth 20 marks of my project!The Judge's Tally Sheet says, for the display:

* legible (up to 3)
* grammatically correct (up to 3 marks)
* logical and self-explanatory (up to 4 marks)
+ visually balanced and uncluttered (up to 5 marks)
* attention-grabbing (up to 5 marks)

Some things I will be finally editing, after I attach the document. Please note that I will be attaching three other pictures on the board as well - one of the sucrose/glucose molecule, one of the acetic acid molecule and one of my own MFC:

* referring to the picture in my text
* writing captions for the pictures
* adding a chemical reaction
* acknowledgments
* editing the Results section

Other topics:
* I will send you the bibliography later this week
* the "second table of information in the results section" shows the average power densities of the entire project, both with no substrate, with sucrose/glucose and with acetic acid.
* There's one problem: thank you for letting me know about sucrose. I checked on the sugar I used, and it was made from cane sugar. So yes, it was sucrose. I changed everything up this morning, replaced all the glucoses to sucroses, replaced all the 6 carbon-atoms to 12-carbon atoms, all the 12 hydrogen atoms to 22 hydrogen atoms. But the problem is that I realized on my CWSF report I already sent in, that I mentioned glucose as my second substrate, not sucrose. So I have two options, change it back to glucose, or tell them that I accidentally wrote glucose. What should I do?

Thanks so much!

EDIT: To eliminate confusion, I switched back to writing glucose. I thought that if I told them that it was an accident, it will create a bad first impression, and it will seem that I'm not taking everything seriously.

Hi Irregular,

What size board are you going to be using, and how much more do you need to edit?

A question on the second table. Does this table have a power value for no substrate, acetic acid, and sucrose? It should include the power output from all three energy sources.

I recommend changing back to sucrose. There is nothing wrong with correcting a mistake once it is discovered, and this is better than perpetuating an error that you are aware of. You can inquire about submitting a corrected report, but if this is not possible, don't worry about it. Now that you aware of the difference between glucose and sucrose, you should use sucrose. Biochemically, there's a big difference between a 12-carbon sugar and a 6-carbon sugar, and it's important to be as accurate as possible. You do not need to apologize for the difference between the report and the board; you learned new information and incorporated into your board, and correcting an error will not create a bad impression at all.

Donna Hardy

Hi Irregular,

One more figure that you should consider adding to the board is a diagram of an MFC, with a description of the function of each component. I imagine that the photograph of your MFC is not large enough to accommodate additional labels, but if it is, you could add the labels to the photograph.

Another good addition, would be an adaptation on the drawing from the website below to show the energy production in an MFC. Be sure to cite your source, since this would not be an original document.

http://www.microbialfuelcell.org/www/in ... nisms.html

Any colorful visual material will complement your data and written text.

Donna Hardy

Hi Donna,

1) The approximate size is 5 1/2 ft by 5 1/2 ft. Since it is rectangular, one side is a little smaller/bigger than the other.

2) I sent the final thing to my dad last night so he could print it using a laser printer, but the copy had glucose written. My school offers lamination on Tuesdays, tomorrow, so I must be finished my copy by tomorrow. I will try my best to edit the information to sucrose. I will definitely keep in mind what you said while talking to the judges. Thanks!

3) I have included a picture of MY MFC and also this diagram of the MFC (which has labels): http://www.microbialfuelcell.org/www/in ... -MFCs.html

Since I'm running a little over time, I will try my best to add this picture to my board, and find some more pictures as well, and possibly edit some information if needed.

Thank you!

Hi Irregular,

You must be back from CWSF? How was it? Did you get any ideas for next year's project?


Donna Hardy

Hi Donna!

Yes, I'm back! Firstly, I'd like to thank you for all your help and advice throughout my entire science fair journey. Your tips, suggestions and enthusiasm made this project considerably successful! I'd like to humbly let you know that I earned a silver medal in my category, Junior Biotechnology&Pharmaceuticals, and a $2 000 scholarship.

Oh my, CWSF was amazing! It was full of a variety of workshops, tours and activities - judging day or not. We had to wake up early and sleep a little late, but it was all worth it, for sure! I made strong friendships, learned a lot, seen other projects, and have a good idea of how my project needs to be like next year. I really enjoyed CWSF (I was really sad on the last day!)and will hopefully come back next year! Wow, it was the best experience I ever had!

For next year's project, I am thinking about entering either an environmental related project again, or maybe one related to medicine. I might do some research and pursue the topic of Microbial Desalination Cells (http://pubs.acs.org/doi/abs/10.1021/es901950j), I will look at articles on the Scientific American website, and will always keep my eyes open for new ideas! The majority of my project idea and research will happen during the summer holidays.

Thanks so much!