Giant bacteria FIVE THOUSAND times bigger than normal are discovered in a mangrove swamp
Scientists have discovered the world’s largest known bacterium, measuring up to one centimeter (0.4 inches) in length.
The species, called Thiomargarita magnifica, was discovered on sunken leaves in the waters of a mangrove swamp in Guadeloupe, Lesser Antilles in the Caribbean.
It looks like thin white filaments like vermicelli paste and contains microscopic sulfur grains that scatter light, giving it a pearly sheen.
The ‘giant’ organism is thousands of times larger than most bacteria and can therefore be seen with the naked eye.
Thiomargarita magnifica ‘challenges the prevailing view of bacterial cell size’ and the assumption that microbes are only visible under a microscope.
Filaments of Thiomargarita magnifica. The ‘giant’ organism is about 50 times larger than all other known giant bacteria and can therefore be seen with the naked eye
“It’s 5,000 times larger than most bacteria,” said Jean-Marie Volland, a marine biologist at Lawrence Berkeley National Laboratory, California.
‘To put it in context, it would be like a human meeting another human being the size of Mount Everest.
“We know it grows and thrives on top of the sediment of the mangrove ecosystem in the Caribbean.
‘In terms of metabolism, it does chemosynthesis, a process analogous to photosynthesis in plants.’
The organism was originally discovered in 2009 by Olivier Gros of the University of the French Antilles in Pointe-à-Pitre, Guadeloupe.
But the find didn’t attract much attention at first — because of its size, Gros thought it was a fungus at the time.
It took Gros and other researchers five years to figure out that the species is actually a bacterium.
The find was described in a pre-print paper in February and has now finally been published in the magazine Science†
“When I saw them, I thought, ‘strange,'” Gros said. “At first I thought it was just something odd, some white filaments to be attached to something in the sediment, like a leaf.”
Thiomargarita magnifica contains microscopic sulfur granules that scatter light, giving it a pearly sheen
The species, called Thiomargarita magnifica, appears as thin white filaments like vermicelli, researchers say
This microscope image provided by the Lawrence Berkeley National Laboratory in June 2022 shows thin strands of Thiomargarita magnifica bacterial cells next to an American dime. The species was discovered among the mangroves of the Guadeloupe Archipelago in the French Caribbean
Volland took on the challenge of showing the organism in three dimensions and at relatively high magnification.
Using various microscopy techniques, such as hard X-ray tomography, he visualized complete filaments up to 9.66 mm (0.38-inches) long.
By definition, bacteria are microscopic single-celled organisms without a distinct nucleus. Bacteria are prokaryotes because they do not have a membrane-bound nucleus.
T. magnifica is a sulfur-oxidizing prokaryote, meaning it derives energy from the oxidation of sulfur compounds.
Large sulfur bacteria have been shown to be hot spots for symbionts – one organism that lives in symbiosis with another.
Silvina Gonzalez-Rizzo, an associate professor of molecular biology at the Université des Antilles, performed gene sequencing to identify and classify the prokaryote.
‘I thought they were eukaryotes; I didn’t think they were bacteria because they were so big with seemingly many filaments,” she said.
“We realized they were unique because it looked like a single cell. The fact that they were a “macro” microbe was fascinating.
†[We called it] magnifica because magnus in Latin means great and I think it’s beautiful like the French word magnifique.’
The organism was first discovered growing as thin white filaments on the surfaces of decaying mangrove leaves in shallow tropical marine mangrove swamps in Guadeloupe, Lesser Antilles
Aerial photographs of the mangroves of the Guadelopue Archipelago of the French Caribbean in the spring of 2022
Another species in the genus Thiomargarita, Thiomargarita namibiensis, was previously the largest known bacterium.
T. namibiensis, found in the ocean sediments of Namibia’s continental shelf, could reach up to 0.75 mm (0.03 in).
As for why T. magnifica is so large, the researchers aren’t so sure. But it is considered unlikely that T. magnifica represents the upper limit of bacterial cell size.
The authors conclude: “The discovery of T. magnifica suggests that large and more complex bacteria can hide in plain sight.”
The researchers hope to grow the bacteria in the lab to learn more about the species.
“Bacteria are endlessly adaptable and always surprising and should never be underestimated,” said Petra Anne Levin, a biologist at Washington University in St. Louis, in a related paper. Perspective†
“Why these organisms have to be so large is an equally intriguing, yet challenging question.”
Levin, who was not involved in the study, points out that bacteria are often defined as microbes — microscopic organisms.
The discovery of T. magnifica shows that this definition should be avoided, as bacteria are not defined by their size.