Scientists Find World's Largest Bacterium 'By Far'

Discovery in Caribbean swamp is big enough to be seen by the naked eye
By Newser Editors and Wire Services
Posted Jun 23, 2022 6:05 PM CDT
Caribbean Swamp Holds World's Biggest Bacterium
This photo provided by the Lawrence Berkeley National Laboratory shows mangroves in the Guadeloupe archipelago in the French Caribbean, where the Thiomargarita magnifica bacteria was discovered.   (Hugo Bret/Lawrence Berkeley National Laboratory via AP)

Scientists have discovered the world's largest bacterium in a Caribbean mangrove swamp. Most bacteria are microscopic, but this one is so big it can 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," said Jean-Marie Volland, a marine biologist at the Lawrence Berkeley National Laboratory and co-author of a paper announcing the discovery Thursday in the journal Science. "It's an amazing discovery," said Petra Levin, a microbiologist at Washington University in St. Louis, who was not involved in the study, the AP reports. "It opens up the question of how many of these giant bacteria are out there—and reminds us we should never, ever underestimate bacteria."

Olivier Gros, a co-author and biologist at the University of the French West Indies and Guiana, found the first example of this bacterium—named Thiomargarita magnifica, or "magnificent sulfur pearl"—clinging to sunken mangrove leaves in the archipelago of Guadeloupe in 2009. But he didn't immediately know it was a bacterium because of its surprisingly large size, just over a third of an inch long. Only later did genetic analysis reveal the organism to be a single bacterial cell. Gros also found the bacterium attached to oyster shells, rocks, and glass bottles in the swamp.

Scientists have not yet been able to grow it in lab culture, per the AP, but the researchers say the cell has a structure that's unusual for bacteria. One key difference: It has a large central compartment, or vacuole, that allows some cell functions to happen in that controlled environment instead of throughout the cell. "The acquisition of this large central vacuole definitely helps a cell to bypass physical limitations ... on how big a cell can be," said Manuel Campos, a biologist at the French National Center for Scientific Research, who was not involved in the study. The researchers said they aren't certain why the bacterium is so large, but Volland hypothesized it may be an adaptation to help it avoid being eaten by smaller organisms.

(Read more bacteria stories.)

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