I wanted to post some of my favorite Winogradsky experiments that I've found so far, if you feel like responding, please add others that you've seen: There was a page that no longer exists from the Woodrow Wilson Foundation Leadership Program for Teachers, but here are some links that are equally good funded by the Foundation: http://www.yale.edu/ynhti/curriculum/units/2010/3/10.03.02.x.html#n and https://www.nabt.org/websites/institution/File/pdfs/american_biology_teacher/2005/067-06-0348.pdf. The BioCurious Meetup Group also posted a nice Winogradsky image from a Brad Bebout workshop has some really beautiful growth! I like this lesson plan as well, posted by Christine L. Case, Ed.D., a Biology Professor at Skyline College. I think it's set up for a community college class, but it could probably be done in almost any classroom (or at home!). Definitely a new favorite website of mine, the Center for Dark Energy Biosphere Investigations posted this blog in 2011 with some excellent thoughts on where to gather your mud and microbes. And how sad I am to have missed this Adopt A Microbe project that they put on that year. What an excellent classroom activity! It might be worth following anyway, even if you missed it in real time. Also, because I found this site fascinating, any teachers out there might be interested in their additional teacher resources and links. Here is NASA's informational video on how to build a Winogradsky Column - a must watch for any microbe geek out there! And my final recommendation for the day will be this animation by Carleton College. Have fun with your microbes and don't forget to post pictures and blog about what happens!

Final Microbial Fuel Cell Report

Description
Microbial Fuel Cells (MFC) work because some of the bacteria (exoelectrogens) found in creek and marine sediment can produce free electrons and these can generate electricity. The microbial activity in my fuel cell continued to be much more significant and interesting than in my spring Winogradsky column. The fuel cell was created using my most active Winogradsky column from last fall. The entire process has been interesting and I would definately do this with a class. Even smaller children enjoy it, as my son, who is in 2nd grade, helped me with the measurements and was able to understand the basic idea that tiny organisms in the mud were creating small amounts of electric current.

Materials and Methods
I used the methods described by Josh McCready and Tess Edmonds at the Geobacter Website: http://www.emunsing.com/portfolio/portfolio_content/44_designLab/MFC_Report.pdf to build my fuel cell with some minor adjustments due to materials availability.*

It is important to note that there are many different configurations and materials employed in constructing an MFC and new methods are being developed all over the world. For the purposes of this class and any use for younger children, I thought it would be best to follow a simple design with the fewest and simplest materials. I therefore followed the idea from the Geobactor site of constructing a sediment MFC, which simply uses sediment as a biomass and bacteria source (anodechamber), the overlying water as a substrate (cathode chamber), and the finer top sediment as a membrane to separate these two ‘chambers’.

Materials used:

• Mud and water originally taken from Bear Creak
• One 24 ounce spaghetti sauce jar
• The anode and cathodes were made with graphite pencils from the art store (the research paper called for carbon paper, but the graphite pencils were cheap and easy to obtain). I used the graphite bricks, as opposed to the thinner pencils.
• Two common metal nuts and bots
• Insulated electrical wire
• Common household sealant
• 1/2 teaspoon of sugar
• 1k-Ohm Metal-Oxide Resistor

We drilled all the way through the graphite and used a nut and bolt to connect the electrical wire. We then coated this area with sealant to help protect against corrosion, this has worked fairly well. Since we had used a nut and bot to connect the wire, we did not use an additional connective epoxy. My MFC did not experience any graphite erosion. The anode section was placed in the sediment and covered at the bottom of the jar. I mixed about a 1/2 teaspoon of sugar into the mud while doing this. The water from the column was added to the jar until it filled the jar to the surface. The Cathode was placed in immediately after. It was made in the same way as the anode.
Results
The MFC has not ever shown a significant voltage, however it has consistently maintained a small voltage since the beginning. By adding sugur or vinager throughout the nine weeks of this experiment, I have seen increased activity on a consistent basis. The most recent results for the voltage are:
4.03.09 0.950 V (immediately after adding vinegar to the MFC)
4.04.09 0.050 V
4.07.09 0.060 V
4.12.09 0.050 V
4.16.09 0.025 V
4.23.09 0.023 V
4.30.09 0.027 V
5.04.09 0.028 V

Conclusion
While there was a slight increase in voltage once the MFC was moved outside and vinager added, my MFC did not display what Josh McCready and Tess Edmonds describe as the results of a "true" fuel cell which include, 1. gradual increased voltage over time as the bacteria populate the electrode, 2. I did not take measurements within any 24 hour period, so I can not varify that the measurements would have oscillated during a 24 hour period as McCready and Edmonds suggest they should (indicating that the microbes go through natural daily cycles of activity), finally, they suggest completely sterilizing the MFC to prove that it will go to zero, validating that the microbes were generating electrical current while alive. I did not do this either.

However, my results due seem to indicate that with further effort, including day and night sampling, regular feeding of the bacteria, and having more than one cell to compare, I may have been able to provide a stronger argument that the fuel cell is an effective generator of electricity. I would also like to attempt to connect it to a small light or toy to prove its effectiveness.

This would be a terrific activity for a class, perhaps creating Winogradsky columns in the first semester and then making them into MFCs in the second semester as a way to complete a unit. I would definately want to havemore MFCs to compare results with and have at least a full three months time to demonstrate the activity with a class.

* The site referenced above is no longer active, but here is a good substitute on the Instructables website: http://www.instructables.com/id/Microbial-Fuel-Cells-A-Way-to-Generate-Clean-Elect/

Final Spring Winogradsky Column Report

Column description
My spring Winogradsky column has left a lot to be desired. There has been very little noticible activity after the cheese turned white, other than a very strong odor coming from the column and forcing me to put it outside. Unlike my previous columns from the fall, this column resulted in few changes in color throughout the ten weeks of the experiment.

Materials and Methods
I used the method described from the Penn State profile: http://www.personal.psu.edu/faculty/j/e/jel5/biofilms/winogradsky.html.

• One column constructed of soil or mud from virtually any source
• Water from the same or a different source
• To these natural components, are added supplemental carbon and sulfur.
• Above the soil is a layer of water and the column is usually covered to retard evaporation.
• The entire column is then illuminated to encourage the growth of phototrophs.

For materials, I used:

• Mud from a backyard puddle
• Puddle water
• Glass vase
• Cut grasses for the carbon source
• Cheese for the sulfer source

Results
Amost immediately the cheese in the middle of the column turned extemely white and has remained so for the entire 10 week experiment. I suggested that these might be some form of fungi - or some form of chemoorganoheterotrophs because they are feeding on organic carbon, light as well as the carbon, and using the carbon for their e- source. I saw no sign of the green or rust colored activity that was so prevalent in my column last semester.

On the surface of the water a thin layer of white biofilm and strong oder began within the first three weeks. Since, the water in the column has overflowed once and the film has turned green with a spiderweb-like subsistance. According to the Microbial World website by Jim Deacon, the layer of biofilm on the surface should be sheathed bacteria.

Conclusion
Considering that there were few other signs of life beyond the cheese fungus, the environment in my column might have been too extreme. I did not take a ph sample, but this might have given me an idea of what the reasons for such little activity were. Possibly the sheathed bacteria were better protected to survive in my tiny extreme environment. For a classroom activity, I liked using a smaller container for myself, but I think that the larger columns would be easier to deal with with children. Also, I would want to have one or more controls available and mud from different environments as well as other carbon and sulfer sources. Possibly I simply did not provide enough cut grass for carbon nutrients.

April 2, 2009: Two updates (pictures to follow):
Microbial Fuel Cell Update: My fuel cell has had very low readings throughout, though I have not been “feeding” the microbes and so I will start a regiment of trying to add vinegar once a week. Interestingly, as a Winogradsky column, this mud and water was not particularly active or smelly, but since I’ve moved it over to the jar and fed it the first batch of sugar, the water has been dark and cloudy for over a month and the smell is so bad I finally had to put it outside. Since being outside, I’ve seen a small jump in voltage. I'm not sure if that's because it's been exposed to more light or it's a coincidence. After learning about the corosion on some of the other MFC projects, I did open the jar and take out the graphite cathode in the water column to check, but it seems to have undergone no corrosion.
3.09.09 0.003 V
3.14.09 0.003 V
3.18.09 0.002 V
3.21.09 0.001 V(column moved outside)
3.23.09 0.001 V
3.28.09 0.004 V
4.01.09 0.004 V
Spring Winogradsky Column UpdateThis column has undergone almost no change since the cheese initially turned white. I have it tightly capped off, and I’m afraid of opening it for the smell. The film on the surface of the water is thicker now and also colored white, but even the water column has not changed much in color. It has just recently started to go a little bit yellow. There is a lot less change than I had detected with my original Bear Creek columns, so I’m wondering if the puddle in my backyard was not as active as Bear Creek or maybe I haven’t given them the right growth materials.

Quick Update on the New Column

For a quick update on my new, but simplistic, Winogradsky column, there is a photo attached here. Also, note several areas of white growth throughout the column. Most prominant is the one shown in the photo here, which seems to be clearly working on the cheese, and is also the side facing the light. These must be the fungi - or at least they are chemoorganoheterotrophs because they are feeding on organic carbon, light as well as the carbon, and using the carbon for their e- source. I partly say this because they are smack in the middle of the column and so theye strict anaerobs. Here is the photo: 

Sacrafice for the Fuel Cell!

I finally have gone and done it. I've sacrificed my favorite Winogradsky Column to the greater good - it is now a microbial fuel cell in the making. I've been carefully considering the methods used by my classmates and have finally settled on this protocol: 

http://www.emunsing.com/portfolio/portfolio_content/44_designLab/MFC_Report.pdf

I found this through the Internet geobacter site (www.geobacter.org), which has some excellent links if you scroll down and also a video clip that I hadn't noticed the first time I went to the site. 

Anyway, I used the following protocol which is to somewhat of a hybrid between the report above, my husband's engineering skills, and what I read from the other students: 

Here is a photo of some of the supplies on our kitchen counter. 

I created one very small microbial fuel cell using the my Winogradsky column from the fall semester, whose original contents were from Bear Creak. If I had mentioned before that there was no significant smell from this column, I was apparently not poking around enough. There was plenty of sulfuric smell coming from the column as I transferred it and the corresponding creak water into the MFC container. I used a 24 ounce spaghetti sauce jar. 

The anode section of the cell was made with a graphite pencil from the art store. The protocol in the research paper asks for carbon paper, but since our entire class is using graphite, I went with graphite. We also drilled all the way through the graphite and used a nut and bolt to connect the electrical wire. Because my husband, the airplane mechanic, was convinced that this would work, we then coated this area with sealant to help protect against corrosion. Since we had used a nut and bot to connect the wire, we did not use an additional connective epoxy. The anode section was then gently placed in the sediment and covered with it at the bottom of the jar. I mixed about a 1/2 teaspoon of sugar into the mud while doing this. 

The water from the column was added to the jar until it filled the jar to the surface. The Cathode was placed in immediately after. It was made in the same way as the anode. A 100 ohm resistor was placed between the wires. I tested the volts immediately after putting everything together (too soon)? I'm going to need to get guidance on the voltmeter. I am not sure what measurement everyone is using, but I read 9 micro volts initially and after 3 hours I'm down to about 3 micro volts. We'll see how this goes with time!

Here is a picture of the wires connected to the two graphite pencils: 

Here are the anode and cathode hanging off the drill while the sealant dries:

Here is a close-up photo of my poor, sacrificed Winogradsky Column after I siphoned off the water, prior to shoveling the mud into the jar: 

Here is the final product, hopefully a solid work of art and advancement for the future of mankind: 

Here is an updated look at my most active fall Winogradsky Column, which is still sitting in the window in my office. This is not a great shot, but you can make out some of the colors in the mud where there should be a mixed area of aerobic and anaerobic activity. This is especially true because I have so much water in this column. Not that much activity can be seen from possible anaerobes at the very base of the bottle, however a broad growth of clearly phototrophic organisms ( greenish, red mass) is growing on the side that always faces the window. I'm guessing that the lowest layers indicate some growth of chemoautotrophs, organisms that are using fermentation. Apparently my rubber band disintegrated and I'll have to get a new one. Also, I think it's important to note that there is no smell coming from this column, though there was a point in the past when it did have a distinctly unpleasent odor.