Our Jar, Week 2
Week 2 went by without much of a visible change in our jar. The microbe colonies are (hopefully!) getting larger, but not yet so large that we can see a difference with our eyes. That shouldn’t come as a surprise; as explained before, it generally takes at least 3 to 4 weeks to startto see microbe colonies in a Winogradsky column.
Ingredient of the Week, and Why We Are Making Microbe Biospheres
Each week, we’re focusing on a different ‘ingredient’ in our jar and discussing why it’s so important. Last week, we talked about water; this week, we’re focusing on carbon. Can you guess where the carbon in our jars comes from? If you guessed the newspaper, you are right (plus, there’s also some carbon in the dirt).
As we discuss carbon, we return again to why we are making microbe biospheres. Although we can’t see microbes with our eyes, microbes are very much a part of our daily lives, whether we're aware of them, or not.
Carbon and Microbes
Carbon is essential to life as we know it. If you could be dried out (all your water taken away) and the rest of you was weighed, half of your body would be carbon.
We eat carbon every day, although we call it “carbohydrate” which means carbon mixed with water. Carbohydrates are “sugars”—not just white sugar, there are lots of different kinds—and we eat them in all sorts of foods, like bread and milk. From these carbohydrates, our body makes energy, energy that we use right away, and energy that gets stored in our bodies for later use.
Microbes use carbon for energy, too. They love the same carbon-based sugars in foods that our bodies do. But some microbes do what we cannot—they “eat” carbohydrates that are too tough for our bodies to use. Cellulose (plant fiber) is such a carbohydrate.
How does carbon get into plants in the first place? Plants take a gas that is floating around in the air—carbon dioxide (a combination of carbon and oxygen) and together with water and sunlight, turn it into carbohydrates, including cellulose. Cellulose is the very building block of plants—it’s what makes plants strong, and stand upright, rather than flop over—their skeleton, so to speak.
We do eat plants (vegetables) and we do get vitamins and minerals from them. However, most of the cellulose from the plants (where the vitamins were stored) passes through our bodies, because the fibers are so tough. Cellulose helps smooth digestion of other foods, but our bodies can’t break it down.
You might think that cows can digest cellulose; after all, they eat lots of grass. But guess what—they can’t—not all by themselves! Can you guess how cows break down all that cellulose? If you said microbes, you are right—microbes living in their rumen help them turn the carbon in grass into energy—for the cows and the microbes.
We humans also take advantage of microbes’ love of carbon in plants when we make linen, a very sturdy (and beautiful) kind of cloth. Linen fibers are spun from flax plants which have been cut and placed in water. There (in a process called “retting”), microbes help soften the stiff flax fibers until they can be broken and eventually made into thread that is then woven into cloth.
Bringing us full circle back to our jar, trees are plants, and just like all plants, trees are made of cellulose. As you might have guessed, microbes can be used to make various forms of paper by breaking down wood fibers into pulp. These days, chemicals are more often used because they’re faster. However, some people are investigating how to use microbes in paper-making again, because it’s more friendly to the environment. Microbes generally are still used to make homemade paper.
Not surprisingly, microbes are made mostly of carbon, just like we are. Scientists believe that oil and coal could be partly made of microbes, including phytoplankton (ocean microbes that we can see as green ‘slime’). These ancient microbes died long ago, perhaps as a sea dried up, and as they became buried under layers of earth (together with other matter), high heat and pressure is thought to have converted them into coal and oil. When we burn coal and oil, we are burning the carbon—and releasing energy—stored in the past by microbes.
All that from bits of newspaper and mud in a jar.