Bread and Microfungi

Fungi are a type of organism that includes the mushrooms we eat. But there are much tinier fungi that are part of some foods. These microscopic forms of fungi are known as microfungi.

Food invaders

First, let’s look at some microfungi that are invaders. Fungi spread through their food source with threads called hyphae. And their food source may well be your food source!

Fungi feed on living things and organic matter (things that were once alive or come from living things). As they do so, they break down their food by releasing chemicals into it.

Moldy bread

Mold is a type of fungus that invades food and breaks it down, causing it to spoil. If you look at a slice of bread and see a patch of mold, you are actually seeing a fungus feeding on the bread. The mold is a network of hyphae called a mycelium.

As the mycelium spreads, the hyphae grow fruiting bodies that hold spores, which are like tiny seeds. When the fruiting bodies release the spores, they travel in the air to find new food to grow on.

Making bread

Yeasts are different from regular fungi. They only have one cell. Carbohydrates—sugar and starch—are the yeast cell’s favorite food. When yeast is mixed with flour and water to make bread, the yeast cells begin to feed on the starch in the flour. This process, called fermentation, releases carbon dioxide bubbles. The bubbles make the bread swell up, or rise. After the bread is cooked, the bubbles appear as holes.


You can see the holes in this bread made by the yeast releasing gas bubbles.



These yeast cells are budding to reproduce themselves. The bud comes off to make a new yeast cell. These cells have been magnified 4,000 times.

How Small Is Small?

An average yeast cell is about 4 micrometers across. There are 1,000 micrometers in a millimeter, so you could line up 250 yeast cells alongside just 1 millimeter on your ruler. You could fit more than 6,000 alongside 1 inch.

What Are You Eating?

You probably think you know what is in the food you are eating. You may be surprised, however, when you see your food under a microscope. Microscopes allow us to see things up close and look at them in a different way. Under the microscope, we can see the tiny parts that foods are made of. We can learn why foods change when we cook them or when they spoil.

Sharing your food

The microscope also shows us that you may not be the only one eating your food! In the refrigerator or on the kitchen counter, tiny organisms (living things) may also be munching away.

Microorganisms and microbes

Organisms too small to see are called microorganisms. They range from tiny animals that you could find with a magnifying glass to living things so small you could fit thousands of them on a grain of salt. Microorganisms that are not animals are often called microbes. Some of these make our food rot. Others make us sick if we eat them. Other microbes actually make food healthy or give it a good taste.

Food up close

Let’s take a look at your food under the microscope and discover what you are really eating. By looking first at two everyday foods—bread and milk—we’re going to learn about two important kinds of microorganisms with which we share our food and our world.



Micro-Monster

The flour mite could live in your kitchen cabinet in a package of flour. In real life, this mite is 0.3 to 0.5 of a millimeter long, so you could see it with a magnifying glass. This is what it looks like when it is magnified 200 times.