Thiomargarita magnifica: What do we know about world's largest bacterium
Bacteria are known for their microscopic sizes and now scientists have discovered one the size and shape of a human eyelash. It is called Thiomargarita magnifica and is described as "by far the largest bacterium known to date." It was found on sunken leaves in a Caribbean mangrove swamp and has not been grown in a lab yet.
- The Thiomargarita magnifica is the biggest single-cell bacterium discovered to date and its internal composition is much more complex than other known bacteria.
- The characteristics and features of the bacterium "indicate gain of complexity in the Thiomargarita lineage and challenge traditional concepts of bacterial cells," according to John-Marie Volland and Olivier Gros, the leading scientists behind the discovery.
Thiomargarita magnifica looks like a thin white filament and is nearly 1cm in size. It does not have key characteristics of the plant or animal cells and is roughly 5,000 times larger than most bacteria. The reason behind their stupendous growth is unknown. Also, unlike other filament-like bacteria found in mangroves which contain hundreds of cells, the magnifica's entire filament is just one cell.
Thiomargarita magnifica is "by far the largest bacteria known to date," says Volland of Lawrence Berkeley National Laboratory and the Laboratory for Research in Complex Systems. "These bacteria are about 5,000 times larger than most bacteria. To put things into perspective, it is the equivalent for us humans to encounter another human who would be as tall as Mount Everest," he added.
Unlike most bacteria that reproduce by dividing into two identical cells, magnifica buds off a small piece at the tip, which floats away and creates a new being. Its surface also has a pristine appearance as it secretes an antibiotic to ward off smaller bacteria.
Generally in other bacteria, genetic material floats freely inside the cell. But in Thiomargarita magnifica, which lives by oxidizing sulfur, things are different. Scientists saw that the genetic information was stored in hundreds of thousands of pepins, which are structures attached to the fluid-filled membrane. Each of these contains DNA and ribosomes, and the pepins collectively store up to 700,000 copies of the genome.
"We really shouldn't underestimate evolution, because we can't guess where it's going to go," said Petra Levin of Washington University. "I would not have guessed this thing exists, but now that I see it, I can see the logic in the evolution to this point."