Microorganisms is a scientific, peer-reviewed, open access journal of microbiology, published monthly online by MDPI.

A microorganism, or microbe, [a] is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from …

Dec 4, 2025 · The major groups of microorganisms—namely bacteria, archaea, fungi (yeasts and molds), algae, protozoa, and viruses—are summarized below. Links to the more detailed articles on …

Mar 28, 2024 · In summation, a microorganism is a minuscule living entity invisible to the unaided eye. This broad classification encompasses a plethora of organisms, including bacteria, archaea, algae, …

Aug 4, 2025 · Microorganisms—organisms too small to be seen with the naked eye—pervade every corner of the planet. They flourish in soil, water, air, and even the most extreme environments …

Microorganisms differ from each other not only in size, but also in structure, habitat, metabolism, and many other characteristics. While we typically think of microorganisms as being unicellular, there are …

Microorganisms are often described as single- celled, or unicellular, organisms; however, some unicellular protists are visible to the human eye, and some multicellular species are microscopic.