Bacteria - Introduction

Introduction

You cannot see them with the naked eye, but the world is teeming with bacteriaSingle-celled microorganisms found in soil, water, plants, and animals that play a key role in the decay of organic matter and the cycling of nutrients. Some are agents of disease. (Singular: bacterium.. They live around you, inside of you, and are found in environments that would kill most every other life form. Bacteria are microbes, organisms that are so small they can only been seen with a microscope. They are the simplest, most abundant, and oldest life form on Earth, having evolved roughly 3.5 billion years ago. That beats other life forms by a long shot including dinosaurs, which only arrived on the scene 250 million years ago, and humans, who appeared a mere 2 million years ago. Scoop up a teaspoon of soil and, if you could see them, you would count about a billion bacteria.

While bacteria often make headline news as the cause of disease, the vast majority are either harmless or helpful to humans. Many bacteria live in the soil and decompose dead plants and animals. This process returns needed nutrients back into the environment, which plants and animals then use to live and grow. Other bacteria change the nitrogen gas from the air into a form of nitrogen that plants needs to survive. For humans, they are used to produce foods, such as yogurt and cheese. Humans and some animals depend on bacteria in their digestive tract to break down the plants they eat so they can process the food. Bacteria are an integral part to all life on Earth.