MudWatt – the Microbial Fuel Cell STEM kid – generates electricity from bacterial poop! Yes, really! The soil under your feet hosts a clean, sustainable source of energy. Geobacter sp. and Shewanella sp., soil bacteria, “poop” electricity. You select the soil, set up the unit, download the app, and wait for the LED to begin blinking. As the number of bacteria increase, the LED blinks faster. The app records and graphs your MudWatt energy, predicts and graphs bacterial populations, and unlocks cool facts and a graphic novel to teach what’s going on. Capture the Waste! When any organisms breaks down food, it releases the energy stored in that food in the form of electrons. With most organisms, from mammals to microbes, the electron “waste” binds to oxygen, iron, or sulfur inside the cell(s) of the organism to conduct other processes. Electrogenic bacteria give off their electrons into the soil around them. An MFC captures those lost electrons using electrodes and wire to complete a circuit and generates electrical current. The energy harnessed can then light up a LED, run a clock, thermometer, or any of a number of other things. Electrogenic bacteria can be found naturally in soils all over
Microbial “Trash” is Human Treasure
We humans have been treasuring and using microbial “trash” for tens of thousands of years. We eat and nurture microbes for their waste products – yes, you eat microbial poop. Metabolic by-products or “waste” would be more appropriate to say in a classroom/polite company, but really – it’s just “poop”. Yogurt, sauerkraut, buttermilk, kefir, bread, beer, wine, cheese, even chocolate, and coffee – are all tasty to us because microbes have eaten the sugars in milk or some plant part. With the exception of corn, whatever you eat goes into your mouth in one form and comes out the other end in a totally different form. Same with microbes. Bacterial Poop: Sugars to Lactic Acid Bacteria like Lactobacillus sp. eat lactose milk sugars and poop out lactic acid. That’s why unflavored, unsugared yogurt is tangy and slightly sour. Same thing with the buttermilk I’ve been culturing recently. YUMMY. Other Lactobacillus sp. eat plant fiber sugars and poop out lactic acid to make sauerkraut and kimchee. Check out a yogurt experiment my girls and I did a while ago. Yes, the girls roll their eyes when I say that they are eating microbial “trash”. Fungal Farts: Sugars to alcohol and carbon