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WASHINGTON — Maximum- Known bacteria – found in the shallow mangrove swamps of the Caribbean Sea and in the form of spring rain large enough to be seen by the naked eye – redefine what is possible for the oldest organism on Earth, the bacterium. increase.
Scientists said Thursday that a bacterium called Thiomargarita magnifica is notable as well as its size. cm) Long – but because its internal structure is different from other bacteria.
DNA, the blueprint for living organisms, is contained within a number of small membrane-bound sac, rather than floating inside cells like most bacteria. The intracellular membrane-bound structure is called the organelle.
"Thousands of times larger than normal-sized bacteria. Discover this bacterium. It's like meeting a human as tall as Mount Everest, "said Jean-Marie Boland, a marine biologist who is co-leader of the US Department of Energy's Joint Genome Institute and California's Complex Systems Institute. I am. Published in the JournalScience
This bacterium was found in several parts of Guadeloupe, the French archipelago of the Caribbean. It was first discovered in the sulfur-rich seawater of the Guadeloupe wetlands by Olivier Gros, a microbiologist and co-leader of the study at Université des Antilles.
"In 2009, I found a long white filament on the sunken leaves of a mangrove tree. I found such a filament intriguing. I. Returned to the lab to analyze them, "Gross said. “I was very surprised to see the giant bacteria inhabiting the mangroves of Guadeloupe.”
Normal bacterial species are 1 to 5 micrometers in length. This species averages 10,000 micrometers (4/10 inch / 1 cm), and some Thiomargarita magnifica are twice as long.
"This is an order of magnitude larger than what we thought was the maximum size possible for a single bacterium," Volland said. "It's about the same size and shape as eyelashes."
The largest bacteria known to date had a maximum length of about 750 micrometers.
Bacteria are unicellular organisms that live almost everywhere on the planet and are essential to their ecosystems and most organisms. Bacteria are the first organisms to inhabit the Earth and are thought to remain very simple in structure after billions of years. People's bodies are full of bacteria, but relatively few cause illness.
Thiomargarita magnifica is not the most famous unicellular organism. Its honor is given to the algae Caulerpa, which can reach 6-12 inches (15-30 cm) in length.
The Caribbean mangrove wetlands are packed with organic matter, and microorganisms in the sediments decompose this material to produce high concentrations of sulfur. The sulfur-rich environment provides an energy source for bacteria such as Thiomargarita Magnifica.
Researchers named the organelle containing its DNA "pepin" after the French word for a small seed in a fruit.
"With two exceptions, no other bacterium was known to retain DNA within the organelles bound to the membrane, which means that it is actually a human cell. It is a characteristic of more complex cells with membrane-bound nuclei, such as cells of animals and plants, "Volland said.
Mapping its genome revealed that thiomargarita magnifica lost some genes essential for cell division and had higher than normal copies of the genes involved in cell elongation.
"This may partially explain why cells grow into such elongated filaments. The genome is also very large, three times the average number normally found in bacteria. Includes. Half of those genes don't know what they are for, "Volland said.
This bacterium shows that life on Earth still has a surprise awaiting discovery, he said.
"Life is fascinating, very diverse, and very complex," Volland added. "It's important to be curious and open."
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