There’s a new record for the biggest bacterium, and you don’t need a microscope to see it.
The newly discovered species, Thiomargarita magnifica, is about an inch long and its cells are surprisingly complex, researchers told Science June 24.
The bacterial giant is about the size and shape of a human eyelash, said marine biologist Jean-Marie Volland of the Menlo Park Complex Systems Research Laboratory in California on June 21 at a news conference. With a maximum of about 2 centimeters, T. magnifica is about 50 times the size of other giant bacteria and about 5,000 times the size of most other medium-sized bacterial species.
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In addition, while the genetic material of most bacteria floats freely inside the cell, T. magnifica packs its DNA into a sac surrounded by a membrane (SN: 22/6/17 ). This compartment is a distinctive seal of the largest and most complex cells of eukaryotes, a group of organisms that includes plants and animals.
Study co-author Oliver Gros, a marine biologist at the Université des Antilles Pointe-á-Pitre in Guadeloupe, France, first discovered T. magnifica while collecting water samples in tropical marine mangrove forests in the Lesser Antilles. of the Caribbean. At first, he confused the long, white filaments like a kind of eukaryote, Gros said at the press conference. But a few years later, genetic tests showed that the organisms were actually bacteria. A closer look at the microscope revealed the sacs containing DNA from the cells.
Previous studies had predicted that the general lack of complexity of bacterial cells meant that there was a limit to how large bacteria could grow. But the new discovery “is breaking our way of thinking about bacteria,” says Ferran Garcia-Pichel, a microbiologist at Arizona State University in Tempe who did not participate in the study. When it comes to bacteria, people usually think small and simple. But that mindset can cause researchers to miss many other bacterial species, Garcia-Pichel says. It’s a bit like thinking that the biggest animal that exists is a small frog, but then scientists discover elephants.
It is still unclear what role T. magnifica plays among mangroves. It is also unknown why it evolved to be so large. One possibility, Volland said, is that having inches long will help cells access both oxygen and sulfur, which bacteria need to survive.