Scientists discover world’s largest bacteria, the first to be visible to the naked eye

Thiomargarita magnifica: In a significant development, researchers have discovered the largest bacterium named 'Thiomargarita magnifica'in the Caribbean, which is an organism that resembles vermicelli.

Key Highlights:

  • The bizarre bacterium has been found in several locations in Guadeloupe, a French archipelago in the Caribbean.
  • While most bacteria are microscopic, this unique organism is big enough to be seen with the naked eye.
  • The thin white filament, approximately the size of a human eyelash, is by far the largest bacterium known to date.
  • The organism is roughly 50 times larger than all other known giant bacteria and is the first to be visible with the naked eye.
  • A normal bacterial species measures 1-5 micrometers long. 
  • This species averages 10,000 micrometers (four-tenths of an inch/1 cm) long, with some twice that length.
  • The discovery has been detailed in a study published in the journal Science.

When was Thiomargarita magnifica first discovered?

  • This bacterium, known as Thiomargarita magnifica, or "magnificent sulphur pearl," was discovered in 2009 clinging to submerged mangrove leaves in the Guadeloupe archipelago by co-author and scientist Olivier Gros.
  • But he didn't immediately know it was a bacterium because of its surprisingly large size, just over a third of an inch (0.9 centimeters) long.

Only later genetic analysis revealed the organism to be a single bacterial cell.

What is Bacteria?

  • Bacteria are single-celled organisms that reside nearly everywhere on the planet, vital to its ecosystems and most living things.
  • Bacteria are thought to have been the first organisms to inhabit Earth and remain quite simple in structure billions of years later.
  • The bodies of people are teeming with bacteria, only a relatively small number of which cause disease.

Additional Info:

Below are the 5 of the largest kinds of bacteria in the world:

Oscillatoria princeps:

  • It was discovered by Vaucher ex Gomont in 1892.
  • Its size is 69.1 µm in width.
  • It is long and cylindrical in shape.
  • Over 100 distinct species of filamentous cyanobacteria belong to the genus Oscillatoria.
  • This genus is also referred to as oxygenic photosynthetic bacteria or "blue-green algae."
  • Blue-green algae inhabit fresh, marine, and brackish waters.
  • Oscillatoria princeps is a symbiotic species that, like certain other flora species, may only reproduce asexually, through fragmentation, or through spore development.


  • Blue-green algae occasionally release poisons when they "bloom," or rapidly proliferate on the water's surface.
  • Toxic algae bloom can cause severe illness or death in animals that drink contaminated water, or come into contact with the algae.

Spirochaeta plicatilis:

  • It was discovered by C.G. Ehrenberg in 1835.
  • Its size is 250 µm in length.
  • It is long and helically coiled in shape.
  • This species of bacteria is believed to be nonparasitic, often inhabiting aquatic environments, and able to survive in both freshwater and saltwater.
  • In addition to giving it an edge in the water, Spirochaeta plicatilis' distinctive flagella enable it to traverse surfaces as gliding bacteria do.
  • This bacterium has the ability to make its way through higher-viscosity liquids than other varieties as well.

Leptospira interrogans:

  • It was discovered by Ryokichi Inada and Yutaka Ido in 1915.
  • Its size is 500 µm in length.
  • It is long and helically coiled in shape.
  • The majority of spirochetes prefer an anaerobic (oxygen-free) environment.
  • They can grow as long as 500 m on occasion.
  • Particularly Leptospira interrogans thrives inside the bodies of animals, away from the dry air.


  • The capacity of these bacteria to proliferate is strongly influenced by the climate because of which leptospirosis outbreaks are most frequent in tropical regions.
  • This bacterium causes Leptospirosis, or “Swineherd’s Disease,” an acute systemic illness that inflames the blood vessels.
  • This disease primarily affects animals, but it can still be transmitted to humans.

For instance, in recent years this disease has sprung up in areas such as India, Brazil and Southeast Asia.

Epulopiscium fishelsoni:

  • It was discovered by Lev Fishelson in 1985.
  • Its size is 600 µm in length.
  • It is elliptical coiled in shape.
  • It has the widest range of cell sizes of any bacterial species.
  • IT is found mainly in the waters of the Red Sea and the coastal waters of Australia.
  • These bacteria were thought to be protists for years after their discovery because of their massive size.
  • The largest specimens of Epulopiscium fishelsoni were originally discovered in the intestinal tracts of Brown Surgeonfish.
  • A symbiotic relationship exists between the bacteria and several varieties of Surgeonfish with the bacteria aiding in the digestion of algae and detritus.

Thiomargarita namibiensis:

  • It was discovered by Heide Schulz and the research team in 1997.
  • Its size is 750 µm in width.
  • It is a chain of cocci in shape.
  • It is found among the sediments of the continental shelf of Namibia, Africa.
  • In reference to the way the bacterial strands appear, the term Thiomargarita means "sulphur pearl."