Microorganism
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A microorganism, or microbe, 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 a
A cluster of Escherichia coli bacteria magnified 10,000 times
Antonie van Leeuwenhoek was the first to study microscopic organisms.
Lazzaro Spallanzani showed that boiling a broth stopped it from decaying.
Louis Pasteur showed that Spallanzani's findings held even if air could enter through a filter that kept particles out.
Bacteria
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Bacteria are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bact
Microorganism
…Microorganisms are extremely diverse, representing most unicellular organisms in all three domains of life: two of the three domains, Archaea and Bacteria, only contain microorganisms. The third domain, Eukaryota, includes all multicellular organisms as well as many unicellular protists and protozoans…
E. coli Bacteria
Rod-shaped Bacillus subtilis
An electron micrograph of Halothiobacillus neapolitanus cells with carboxysomes inside, with arrows highlighting visible carboxysomes. Scale bars indicate 100 nm
The exterior of Pseudomonas, a genus of Gram-negative Bacteria.