Part 4

Micro chefs Who would have thought microbes could also be helpful in the kitchen? We've been using fungi and bacteria in a process called fermentation for thousands of years. This process makes food last longer and makes it more delicious. Fermentation Yeasts are a type of fungus made of one cell. They change sugars into other molecules, such as alcohol and carbon dioxide gas, through fermentation. This is why people use yeast to make drinks like wine. 1 The first step in making wine involves crushing a lot of grapes. Traditionally people did this by stamping on the grapes with their feet! 2 Grapes have natural yeast on their skins. Crushing them mixes the yeast with the sugar inside. This starts the process of fermentation. 3 The yeast dies when the amount of alcohol becomes too high for it. If the wine is bottled before the yeast dies, bubbles of carbon dioxide are trapped, making it fizzy. Favorite foods Fermentation is used in a few unexpected products. Here are some of the world's favorite fermented foods. Bread Yeast is added to bread dough to make bubbles of carbon dioxide. The gas is trapped in the dough, and that's what makes bread light and fluffy. The holes in bread are made by carbon dioxide gas. Kimchi Kimchi is a traditional Korean side dish made from cabbage and other vegetables. Bacteria ferment the cabbage to give it a sour taste. Cheese When one of the sugars in milk, called lactose, is fermented using bacteria, it makes lactic acid. Lactic acid is what gives cheese its tangy flavor. Yogurt Like cheese, yogurt is made by fermenting the sugars in milk. One of the main microbes responsible is a bacteria called Lactobacillus (lak-toh-bah-SILL-us).

Zombie ants! We normally think of fungi growing on dead plants and animals. However, some can grow inside living creatures, and even change their behavior. One freaky fungus even turns ants into zombies. Mind control When the spores of a certain fungus, called Ophiocordyceps unilateralis, land on an ant, they spread through the ant's body. Before long, the fungus will completely take over the ant's mind and behavior. 1 Spores land Spores fall from a fungus and land on an ant. They use special chemicals called enzymes to break into the ant's body. 2 Fungus infects The fungus cells multiply and spread through the ant. They release more chemicals that change the ant's behavior. 3 Ant climbs The fungus forces the ant to climb up to the top of a plant and bite down hard. 4 Fungus sprouts Now anchored to the plant by its strong jaws, the ant dies. The fungus growing inside the ant bursts out in long stalks. Fungus stalks sprout from the ant's head. The balls of fungus at the end of the stalks, called sporangia, will burst, releasing lots and lots of spores. The ant stays anchored to the plant even after it dies. 5 Cycle continues The fungus releases more spores, which fall onto other unsuspecting ants below, making new zombie ants. FUNGUS FARMERS Not all fungi are bad for ants. In fact, leaf-cutting ants grow fungi like crops. They take pieces of leaves to their undergroud nests. When fungus grows on the leaves, the ants farm it and eat it.

What are algae? Have you ever seen what looks like green slime growing on a lake or pond? That's probably algae! This microbe is known for its color—but not all algae are green. The variety of these amazing creatures may surprise you. Diatoms These are a type of algae called diatoms. Each diatom is made of only one cell. They have shells made of opal, which is a bit like glass, and they're covered in intricate ridges and holes. Some diatoms are circles, while others are triangles, squares, or stars. Diatoms are see-through, like pieces of glass. Zoochlorella and kelp Algae come in many different shapes and sizes, from single-celled microscopic creatures to giant multi-celled seaweed. Zoochlorella Each of these teeny green blobs is its own single-celled algae called zoochlorella. Zoochlorella only live inside other creatures. Kelp Kelp is a type of algae called seaweed. It is usually brown and grows underwater in giant forests. In and out The hard shell of a diatom is impermeable—nothing can flow through it. That's why it's covered in small holes. The holes let in nutrients and let out waste products.

Growing green All algae have the same energy source. Just like plants, algae get energy from the sun in a process called photosynthesis. During this process, they also take in carbon dioxide gas and use it to make oxygen. Algal bloom When the temperature, sunlight, and other conditions are just right, algae can take over a pond, a lake, or even a large area of the ocean. These big, green bodies are called algal blooms, and they're quite a sight. Look closer These freshwater algae are green because of special molecules inside them called chlorophyll. The chlorophyll helps with photosynthesis. Algae are like the trees and grass of our oceans, lakes, ponds, and rivers. Like plants, they take in sunlight and use it to make sugar and oxygen. About half of the oxygen we breathe is made by algae! Energy from the sun The chlorophyll molecules inside algae take in energy from the sun and store it as sugar. Algae can use the sugar to move and grow. Some animals, such as this snail, eat algae, They want to use the high-energy sugar to move and grow, too!

What are protozoa? Protozoa are made of one cell each, like bacteria, but they are actually more closely related to plants and animals. They behave like animals, too, by moving around and eating other living things. Amoeba An amoeba is a type of protozoa that looks like a splotch of jelly and can change shape constantly. It moves and eats by sending out leg-like limbs. Some amoebas prey on and eat other simple organisms, such as bacteria. 1 The amoeba sends out limbs to completely surround a bacteria. 2 These little sacks of enzymes, called lysosomes, move into attack position. 3 Once the bacteria is fully captured, the lysosomes release their enzymes. They break down the bacteria into nutrients, which are taken in by the amoeba as food. The cell membrane of an amoeba is very flexible and fluid. Cytoplasm makes up most of the inside of an amoeba. The amoeba's DNA is found in a central pouch called a nucleus. AMOEBAS Amoebas can sense chemicals given off by their food. This is like our sense of smell. THAT'S HUGE! Most creatures made of one cell are tiny, but not all. This amoeba is called a xenophyophore (zen-oh-FI-oh-fore). It's the biggest single-celled organism we know. It can grow up to 8 in (20 cm) across—bigger than your hand! Protozoa pals As well as amoebas, there are two other major types of protozoa. They are the ciliates and the flagellates. Ciliates Ciliates are covered in hair-like strands called cilia. They use them to move, eat, sense, and hold on to things. Flagellates Flagellates have at least one long tail, called a flagellum, that they use to swim. Some flagellates cause diseases in humans.

What are archaea? Archaea also look a lot like bacteria, but their cell membranes are super strong. Archaea are known for being able to live in really extreme places where other microbes couldn't survive. Hot stuff Some archaea live in temperatures around 212°F (100°C)! They are called hyperthermophiles. High temperatures cause important molecules like DNA to break, so hyperthermophiles need to be really good at fixing broken molecules. The cell membrane of a hyperthermophile is strong to help it survive extreme heat, such as near an underwater vent. What is an underwater vent? Water seeps into cracks in the ocean floor where it's heated by hot rocks and magma. It then emerges in places called hydrothermal vents, which are like underwater volcanoes. Hyperthermophiles can be found living here. Archaea can have more than one flagellum, or tail, to help them move around. Where hot water from the vent meets cold water in the ocean, dark "smoke" forms. Hot water spews out the top of an underwater vent. Extreme archaea Archaea aren't only found living in high temperatures. Some archaea have made their home in other extreme environments. Surviving salt Scientists used to think nothing could survive in really salty water. However, some archaea can live in water that is 10 times saltier than the ocean. Resisting radiation Certain types of archaea can survive 3,000 times the exposure to a kind of energy, called radiation, that would kill a human. These creatures are truly tough. There are no diseases caused by archaea. MICROBE RAINBOW Not all extreme microbes are archaea. These beautiful rainbow colors circling the Grand Prismatic Spring at Yellowstone National Park in Wyoming are actually created by heat-loving bacteria.