Microbes are organisms that cannot be seen with the naked eye. They include bacteria, archaea, protists, viruses, prions, and fungi. They account for most of the diversity of life on Earth. Far more microbes inhabit a single person’s body than there are people on the entire planet. Microbes also dominate in terms of their ability to live and thrive in extreme environments, including clouds, deep-sea volcanoes, springs, ice caps, and animal intestines.
Most animals, including humans, exhibit numerous associations with microbes. Our "human microbiome" includes our skin, hair, mouth, and gut.
Humans typically associate microbes with disease. Most of our human microbiome, however, is neutral or even beneficial. Microbes help digest food, absorb nutrients, and out-compete harmful bacteria in the intestines. They produce vitamins and proteins that human genes cannot produce. They prevent the growth of harmful skin bacteria and further aid the immune system in fighting infections and diseases throughout the human body.
- The microbes that inhabit a single person outnumber the human cells ten to one and can weigh approximately 1.4 kilograms (3 pounds).
- In addition to the human microbiome, microbes live in plants, soil, oceans, and the atmosphere. These microbiomes maintain healthy function of these diverse ecosystems, influencing human health, climate change, food security, and other factors.
- Escherichia coli is a bacterium that is one of the most well-studied microbes in our human microbiome. E.coli can cause severe intestinal illnesses, but also plays an important role in providing humans with vitamin K.
- The air around you may be as distinctive as a fingerprint. The human body emits bacteria into the air, and the resulting microbial cloud may be used to uniquely identify the person.
Term Part of Speech Definition Encyclopedic Entry archaea Plural Noun
(singular: archaeon) a group of tiny organisms often living in extreme environments, such as ocean vents and salt lakes.
bacteria Plural Noun
(singular: bacterium) single-celled organisms found in every ecosystem on Earth.
visible mass of tiny water droplets or ice crystals in Earth's atmosphere.
Encyclopedic Entry: cloud digest Verb
to convert food into nutrients that can be absorbed.
a harmful condition of a body part or organ.
fungi Plural Noun
(singular: fungus) organisms that survive by decomposing and absorbing nutrients in organic material such as soil or dead organisms.
part of DNA that is the basic unit of heredity.
human microbiome Noun
collection of microorganisms that reside on the surface and in deep layers of the skin, mouth, eyes, and gut of living human beings. The human biome includes bacteria, fungi, and archaea, but does not include microscopic animals.
ice cap Noun
area of fewer than 50,000 square kilometers (19,000 square miles) covered by ice.
Encyclopedic Entry: ice cap immune system Noun
network of chemicals and organs that protects the body from disease.
tubular system in the human digestive system, which regulates elimination of waste products from the body.
tiny organism, usually a bacterium.
substance an organism needs for energy, growth, and life.
Encyclopedic Entry: nutrient organism Noun
living or once-living thing.
microscopic particle of protein that is thought to be able to self-replicate and to be the agent of infection in a variety of diseases of the nervous system.
one of many complex compounds, made of chains of amino acids, that make up the majority of all cellular structures and are necessary for biological processes.
type of microscopic organism (not an animal, plant, or fungus).
small flow of water flowing naturally from an underground water source.
pathogenic agent that lives and multiplies in a living cell.
chemical substance that is necessary for health.
an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.
Encyclopedic Entry: volcano
This material is based in part upon work supported by the National Science Foundation under Grant No. DRL-0840250. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation.
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