How could something so small be so big? Microbes are single-cell organisms that are so puny that millions of them can fit into the eye of a needle.  Microbes include fungi, bacteria, and protists.  They live just about everywhere: the soil, water, air, animals, rocks, and even us! A single teaspoon of soil contains A LOT of microbes: about 1,000,000 bacteria, 120,000 fungi, and 25,000 algae! Microbes are very important as the decompose organic matter, fix nutrients from the atmosphere and make it usable for plants, and they even help protect our immune systems!

Microbes are responsible for many things. For example, they decompose organic matter. This means that they break down dead things into nutrients that can be recycled by living things. Let’s say you take the humus layer of soil, which is a layer on top of the soil that collects decaying organic matter. Microbes will decompose the organic matter by feeding upon the decaying organic materials in the humus layer. The process of decomposing may take longer or shorter, depending on temperature conditions, moisture, and oxygen. If the weather is too arid the bacteria and fungi will dry out and are unable to take part in the decomposition process. The moisture is required for the plants to reproduce and to actively decompose the organic matter. Microbes also require a source of oxygen to respire.

Microbes are also important as they fix nutrients from the atmosphere and make it usable for plants. Some of these microbes are called rhizobia. Rhizobia are soil bacteria that help the formation of nodules on roots of their plants. Nodules are a part of the plant stem where one or more leaves intersect, forming a slight swelling. Inside the nodules is where the rhizobia fix nitrogen. This means that they convert dinitrogen into ammonia, of which then the bacteria will pass it to the plant to sustain its nutritional need for nitrogen. Dinitrogen makes up 80% of the air we breathe. Fixing nitrogen is an energy-intensive job, but the carbon compounds from the plant fuel the bacteria.

Microbes can also protect our immune system. For example, in our bodies there are millions of microbes and numerous colonies of microbes are in the vaginal canal. When a baby is born vaginally, rather than via the C-section, the baby ingests lots of important microbes that build up their immune systems. This is why when a baby is born via the C-section it may have a weaker immune system, because it wasn’t provided with the same microbes. Microbes help block out any nasty bacteria while the human body digests. There are actually ten times more microbial cells in the human body than human cells.

As you can see, microbes help decompose organic matter, take nutrients from the atmosphere to store and they protect our immune system. They are in everything and everywhere. They are part of our dirt, our plants, and our bodies. Without them we would be sick and unhealthy, the plants would be wilted, and the soil would not be rich. We are dependent on microbes, they are part of us.

(Photos by Elke Cruden,  Isabel Wijsen, and Roxy McDonald)

Written by Ruby Newman