Is “bacteria” plural or singular?
Bacteria is plural; bacterium is singular. What’s with the word bacteria, and why does it behave the way it does from its singular to plural form? Keep reading.
Many bacteria are beneficial for digestion.
A single bacterium is responsible for the disease.
Some bacteria is harmful to humans.
We isolated several bacterium from the sample.
What the definition of bacteria?
According to the Online Dictionary, the word bacteria is understood as:
Bacteria are small single-celled organisms. Bacteria are found almost everywhere on Earth and are vital to the planet’s ecosystems.
What’s the plural of bacteria?
The plural of bacteria is bacteria. Bacterium is singular.
Nouns that end in -um / -a
| singular | plural |
|---|---|
| phenomenon | phenomena or phenomenons |
| criterion | criteria |
| bacterion | bacteria |
| medium | media |
| datum | data |
| spectrum | spectra or spectrums |
“bacteria” as the plural by associating it with “many” — many bacteria are helpful; “bacterium” is the singular, like one bacterium causes disease.
“Bacteria”, used in sentences
1. Some bacteria are entomopathogens.
2. Then a starter culture of lactic streptococci and lactobacilli bacteria is added.
3. Numbers of bacteria were measured using soil dilution plating on soil extract agar media.
4. Foods containing these bacteria include yogurt, kefir, sauerkraut, miso, and tempeh.
5. In the low-oxygen conditions there, thick mats of sulfate-reducing bacteria grew on the carbonate rocks.
Examples of bacterium in context
1. The endotoxic activity of the live bacterium was studied by feeding this to the worms in the lawn.
2. The bacterium contains a plasmid, a circular piece of DNA that holds the gene and promoter sequence.
3. This bacterium causes infections in the genital tract that may disseminate to organs.
4. Lyme disease is an infectious illness caused by the bacterium Borrelia burgdorferi.
5. At one time it was believed that the bacterium lived in the soil like its relative that causes galls on other plants.
Origin of the word bacteria
From Etymonline on bacteria:
Unicellular microorganisms which lack an organized nucleus,” and sometimes cause disease, 1847, plural of Modern Latin bacterium.
What’s the difference between they’re, their, and there?
Sources
Work Sheet
According to the post, which word is the plural form?
According to the post, which word is the singular form?
When using the word ‘bacteria’ as the subject, what type of verb should you typically use?
When using the word ‘bacterium’ as the subject, what type of verb should you typically use?
Which of the following examples from the post shows incorrect usage?
Foods containing these include yogurt, kefir, sauerkraut, miso, and tempeh.
Lyme disease is an infectious illness caused by the Borrelia burgdorferi.
Many are beneficial for digestion.
A single is responsible for the disease.
You can associate the word ‘bacteria’ with to remember it’s plural.
Frequently Asked Questions
Is bacteria singular or plural?
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What is the singular form of bacteria?
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How should “bacteria” be used with verbs?
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How should “bacterium” be used with verbs?
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What’s a common mistake using bacterium?
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Yash, D. "Is Bacteria Plural or Singular?." Grammarflex, Jun 20, 2025, https://www.grammarflex.com/is-bacteria-plural-or-singular/.
