Thomas Basic
Clinging to submerged debris in shallow marine mangrove forests in the French Caribbean, threadlike microorganisms — perfectly visible to the naked eye — have earned the title of largest bacteria ever known.
At about an inch in length, they are about the size and shape of a human eyelash, beating the competition at about 5,000 times the size of the diverse bacteria in the garden and 50 times the size of the bacteria that once grew to be giant. considered. In human terms, this is like seeing someone as tall as Mount Everest.
Pierre-Yves Pascal
Prokaryotes were discovered in 2009 by Olivier Gross, a biologist at the University of the Antilles, and found them swinging gently in sulfur-rich waters among the mangroves of the Guadeloupe archipelago. Gross said in a news conference that the bacteria clung to the leaves, branches, shells of oysters and bottles that sank in the tropical swamp.
He and his colleagues initially thought they might be complex eukaryotes or maybe a set of related organisms. But years of genetic and molecular research have shown that each streak is, in fact, a towering bacterial cell, genetically related to other sulfur-oxidizing bacteria. “That was, of course, a huge surprise,” Jean-Marie Voland, a microbiologist at the Joint Genome Institute in Berkeley, Calif., said at the news conference.
Gross and his colleagues posted this week An article in Science explaining everything they’ve learned About the formidable new bacteria they named Candidate (Californië) Thiomargarita Magnifica.
Their findings expand our understanding of microbial diversity in ways microbiologists never thought possible. Scientists previously hypothesized that the size of bacteria would be limited by several factors, including a lack of intracellular transport systems, a reliance on inefficient chemical diffusion, and the surface-to-volume ratio needed to meet energy needs. However, the size of a California. T. Magnifica The cell is at least twice an order of magnitude higher than the expected maximum the bacteria could theoretically reach, Volland said.
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strings California. Thiomargarita magnifica.
Jean-Marie Voland
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strings California. Thiomargarita magnifica.
Jean-Marie Voland
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Voland, Gross and colleagues are still learning how—and exactly why—California. T. Magnifica Manages its massive size. But so far it is clear that California. T. Magnifica It oxidizes hydrogen sulfide from its sulfur-rich environment and reduces nitrates. About 75 percent of the cell’s volume is a bag of stored nitrate. The cyst crushes against the cell envelope, limiting the depth to which nutrients and other molecules must diffuse.
While bacteria usually have floating DNA, California. T. Magnifica It appears to have more than half a million copies of its genome, grouped into several membrane-bound compartments that the researchers named pipiens, after the tiny seeds inside the fruit. The spread of pepinates over the outer edges of the bacteria would allow for local protein production, eliminating the need to transport proteins over long distances.
The next step in studying these giant bacteria is for scientists to figure out how to grow them in labs. Currently, researchers collect new samples from the mangrove forests every time they run out. But this was tricky because they seem to have an ambiguous or seasonal life cycle. Gros hasn’t been able to find one for the past two months. “I don’t know where they are,” he said.
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