Definition of bacterium in English:

bacterium

nounPlural bacteria

  • A member of a large group of unicellular microorganisms which have cell walls but lack organelles and an organized nucleus, including some which can cause disease.

    • ‘A urine test can also be used to confirm that the bacteria are the Legionella bacteria.’
    • ‘After the patient takes the antibiotic, it is absorbed through the cell wall of the bacterium.’
    • ‘The disease is a form of pneumonia caused by bacteria which live in water droplets.’
    • ‘Almost any germ, whether a bacterium or a virus, may be responsible.’
    • ‘Most chest infections are usually caused by germs such as bacteria or viruses.’
    • ‘In Peru, ballast water has been blamed for the introduction of a bacterium that causes cholera.’
    • ‘The cholera bacterium may also live in the environment in brackish rivers and coastal waters.’
    • ‘The free radicals have the additional benefit of killing bacteria, viruses and spores.’
    • ‘Typhoid fever is a serious infection caused by the bacterium Salmonella typhi.’
    • ‘He added that because the virus was not a bacterium, it could not be brought under control by the use of antibiotics.’
    • ‘The toxin produced by the diphtheria bacteria may also damage the heart and the nervous system.’
    • ‘Various germs such as fungi and bacteria live harmlessly on the skin and inside the body.’
    • ‘The membrane lipids of thermophilic bacteria are rich in saturated fatty acids.’
    • ‘The pneumococcal bacterium is the second most common cause of bacterial meningitis.’
    • ‘Antibiotics cannot treat roseola because it is caused by a virus, not a bacterium.’
    • ‘The bugs are only a few thousandths of a millimetre across and lack the cell walls which most bacteria have.’
    • ‘A gene from a human pathogen is inserted into a bacterium that infects plants.’
    • ‘It is an acute, life-threatening febrile illness caused by the bacterium Salmonella typhi.’
    • ‘Its main study area is infectious diseases caused by viruses, bacteria and parasites.’
    • ‘It could only be detected by its ability to kill bacteria on a petri dish.’
    illness, ailment, infection, disease, disorder, sickness, affliction, malady, complaint, upset, condition, infirmity, indisposition, malaise
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Bacteria are widely distributed in soil, water, and air, and on or in the tissues of plants and animals. Formerly included in the plant kingdom, they are now classified separately (as prokaryotes). They play a vital role in global ecology, as the chemical changes they bring about include those of organic decay and nitrogen fixation. Much modern biochemical knowledge has been gained from the study of bacteria, as they grow easily and reproduce rapidly in laboratory cultures

Usage

Bacteria is the plural form (derived from Latin) of bacterium. Like any other plural it should be used with the plural form of the verb: the bacteria causing salmonella are killed by thorough cooking, not the bacteria causing salmonella is killed by thorough cooking. However, the unfamiliarity of the form means that bacteria is sometimes mistakenly treated as a singular form, as in the example above

Origin

Mid 19th century: modern Latin, from Greek baktērion, diminutive of baktēria ‘staff, cane’ (because the first ones to be discovered were rod-shaped). Compare with bacillus.

Pronunciation

bacterium

/bakˈtɪərɪəm/