WASHINGTON — Scientists have discovered the world’s largest bacterium in a Caribbean mangrove.
Most bacteria are microscopic, but this one is so large it can be seen with the naked eye.
The thin white filament, about the size of a human eyelash, is “by far the largest bacteria known to date,” said Jean-Marie Volland, marine biologist at Lawrence Berkeley National Laboratory and co-author of an article announcing the discovery. Thursday in the journal Science.
Olivier Gros, co-author and biologist at the University of the French West Indies and Guyana, found the first example of this bacterium – named Thiomargarita magnifica, or “magnificent sulfur pearl” – clinging to mangrove leaves embedded in the archipelago of Guadeloupe in 2009.
But he didn’t immediately know it was bacteria due to its surprisingly large size, just over a third of an inch (0.9 centimeters) long. Only subsequent genetic analysis revealed that the organism was a single bacterial cell.
“It’s an incredible finding,” 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 exist – and reminds us that we should never, ever underestimate bacteria.”
Gros also found the bacteria attached to oyster shells, rocks and glass bottles in the swamp.
Scientists haven’t been able to grow it in the lab yet, but researchers say the cell has an unusual structure for bacteria. One key difference: it has a large central compartment, or vacuole, that allows certain cellular functions to occur in this controlled environment rather than throughout the cell.
“Acquiring this large central vacuole definitely helps a cell circumvent physical limitations…on a cell’s size,” said Manuel Campos, a biologist at the French National Center for Scientific Research, who did not participated in the study.
The researchers said they weren’t sure why the bacteria was so large, but co-author Volland speculated it could be an adaptation to help it avoid being eaten by smaller organizations.