bacterium science definition
Plural bacteria bacteria
Any of a large group of one-celled organisms that lack a cell nucleus, reproduce by fission or by forming spores, and in some cases cause disease. They are the most abundant lifeforms on Earth, and are found in all living things and in all of the Earth's environments. Bacteria usually live off other organisms. Bacteria make up most of the kingdom of prokaryotes (Monera or Prokaryota), with one group (the archaea or archaebacteria) often classified as a separate kingdom. See also archaeon, prokaryote.
It is important to remember that bacteria
is the plural of bacterium,
and that saying a bacteria
is incorrect. It is correct to say The soil sample contains millions of bacteria,
and Tetanus is caused by a bacterium.
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