About Microbes
Microbe is an informal word for things too small to see clearly without magnification. The microbial world includes bacteria, archaea, microscopic fungi, many protists, and often viruses, although viruses are not cells and scientists debate how to describe their status as living or nonliving.
Bacteria
Bacteria are single-celled prokaryotes.
Learn MoreArchaea
Archaea are another major group of prokaryotic cells.
Learn MoreMicroscopic Fungi
Yeasts and molds are fungi, not bacteria.
Learn MoreProtists
Many microscopic eukaryotes are grouped informally as protists.
Learn MoreViruses
Viruses are much smaller than most cells and cannot reproduce on their own.
Learn MoreDifferent Sizes
Microbes exist across a huge size range.
Learn MoreMicrobial Ecosystems
Microbes live in communities rather than isolation.
Learn MoreMicrobiomes
A microbiome is a community of microorganisms and their genes in a particular environment.
Learn MoreBacteria
They have cell membranes, DNA, ribosomes, and many have cell walls. Bacteria can reproduce independently when conditions allow and perform a huge range of metabolic reactions.
Archaea
They may look similar to bacteria, but their genetics, membranes, and molecular machinery are different. Archaea occur in oceans, soils, animal microbiomes, and extreme environments.
Microscopic Fungi
Fungal cells have nuclei and are more closely related to animals than to bacteria. Yeasts can be single-celled, while molds grow as networks of microscopic filaments.
Protists
Protists include amoebas, ciliates, many algae, and numerous other lineages. They have cells with nuclei and can be predators, photosynthesizers, parasites, or important members of aquatic food webs.
Viruses
A virus contains genetic material inside a protein coat, and some have an outer membrane. It must enter a host cell and use that cell's machinery to make more virus particles.
Different Sizes
Many bacteria are around one to several micrometers long. Viruses are generally much smaller, while some single-celled protists are large enough to see as tiny specks. Size alone cannot tell you what kind of microbe something is.
Microbial Ecosystems
A spoonful of soil, a drop of pond water, or the human mouth can contain many species interacting at once. They compete for nutrients, exchange chemicals, form partnerships, and influence their environment.
Microbiomes
Scientists study microbiomes in soil, oceans, buildings, plants, animals, and people. Modern DNA sequencing can identify many organisms that are difficult to grow in laboratories.