Microbiology

Introduction
Historical background
- Spontaneous generation versus biotic generation of life
- Microbes and disease
- Progress in the 20th century
Types of microorganisms
- Bacteria (eubacteria and archaea)
- Algae
- Fungi
- Protozoa
- Viruses
- Prions
- Lichens
- Slime molds
The study of microorganisms
- Basic microbiology
  - Morphology
    - Light microscopy
    - Electron microscopy
  - Nutritional and physiological characteristics
  - Reproduction and growth
  - Metabolism
  - Pathogenesis
  - Antigenic characteristics
  - Genetic characterization
- Applied microbiology
  - Soil microbiology
  - Microbiology of water supplies, wastewater, and other aquatic environments
  - Food microbiology
    - Food spoilage
    - Food preservation
    - Food products from microorganisms
  - Industrial microbiology and genetic engineering
  - Medical and public health microbiology
  - Plant pathology

References & Edit History Related Topics

Images & Videos

Uncover the potential of technology in the field of microbiological research

Labeled diagram of a bacillus-shaped bacterial cell showing capsule, cell wall, cell membrane, cytoplasm, nuclear matter, pili, and a single long flagellum extending from one end.

Aerial view of wastewater treatment basins with circular clarifiers; overlaid toilet graphic and arrow with text reading: “Where does it go?”

How smart tags can indicate food spoilage

At a Glance

microbiology summary

Quizzes

greylag. Flock of Greylag geese during their winter migration at Bosque del Apache National Refugee, New Mexico. greylag goose (Anser anser)

Biology Bonanza

Mushrooms growing in forest. (vegetable; fungus; mushroom; macrofungi; epigeous)

Science at Random Quiz

Related Questions

How are microorganisms used to make antibiotics and insulin?
How can algae be microscopic or grow into large multicellular forms?
How can antibiotic use disrupt the gut microbiome?
How did John Tyndall's experiments support Louis Pasteur's findings about microbes in air?
How did Joseph Lister reduce infections during surgery?
How did Louis Pasteur disprove spontaneous generation?
How did Louis Pasteur's work lead to pasteurization of milk?
How did Robert Koch connect specific microorganisms to specific diseases?
How did hand and clothing disinfection reduce puerperal fever?
How did ribosomal RNA research change the classification of microorganisms?
How do archaeal cell walls differ from bacterial cell walls?
How do bacteria reproduce by binary fission?
How do bacterial shapes include spheres rods and spirals?
How do decomposer microorganisms recycle nutrients in ecosystems?
How do fungi decompose wood and other complex materials?
How do gut bacteria help protect the human body from harmful microbes?
How do heterotrophic microorganisms obtain carbon for growth?
How do methane-producing archaea obtain energy in oxygen-free environments?
How do microorganisms help make yogurt and cheese?
How do nitrogen-fixing bacteria help plants grow?
How do psychrophiles differ from mesophiles and thermophiles?
How do scientists identify bacteria with biochemical tests?
How does the Gram stain distinguish gram-positive bacteria from gram-negative bacteria?
How does the human microbiome help with digestion?
How does yeast make bread dough rise?
How quickly can some bacterial populations double under ideal conditions?
What are Koch's postulates used to prove?
What areas of science can microbiologists specialize in?
What did Antonie van Leeuwenhoek observe in saliva and teeth scrapings?
Where can microorganisms live on Earth?
Where do algae commonly live?
Which groups of microorganisms are studied in microbiology?
Which kinds of microorganisms can cause infectious diseases?
Which microorganisms cause malaria and influenza?
Why are some archaea called extremophiles?
Why did Carl Woese propose separating Archaea from Bacteria?
Why do microbiologists grow microbes in pure cultures?
Why is agar used to make solid media for growing microorganisms?
Why was the invention of the microscope important to microbiology?
How is genetic testing done?

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External Websites

Verywell Health - An Overview of Microbiology
Oregon State University Pressbooks - General Microbiology - Microbiology
National Center for Biotechnology Information - PubMed Central - The Basic Concept of Microbiology
Stanford Encyclopedia of Philosophy - Philosophy of Microbiology

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Articles from Britannica Encyclopedias for elementary and high school students.

microbiology - Student Encyclopedia (Ages 11 and up)

Microbiology

biology

Written by

Michael J. Pelczar

Emeritus Vice President for Graduate Studies and Research; Emeritus Professor of Microbiology, University of Maryland, College Park. Emeritus President, Council of Graduate Schools. Coauthor of Microbiology;...

Michael J. PelczarAll

Fact-checked by

Britannica Editors

Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....

Britannica Editors

Last updated

Nov. 12, 2026 •History

Microbiology, study of microorganisms, or microbes, a diverse group of generally minute simple life-forms that include bacteria, archaea, algae, fungi, protozoa, and viruses. The field is concerned with the structure, function, and classification of such organisms and with ways of both exploiting and controlling their activities. The 17th-century discovery of living forms existing invisible to the naked eye was a significant milestone in the history of science, for from the 13th century onward it had...

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