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.
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 (0.9 centimeters) long. Only later genetic analysis revealed the organism to be a single bacterial cell.
“It's an amazing discovery,” said Petra Levin, a microbiologist at Washington University in St Louis, who was not involved in the study. “It opens up the question of how many of these giant bacteria are out there — and reminds us we should never, ever underestimate bacteria.”
Gros also found the bacterium attached to oyster shells, rocks and glass bottles in the swamp.
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Scientists have not yet been able to grow it in lab culture, 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 co-author Volland hypothesized it may be an adaptation to help it avoid being eaten by smaller organisms.
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