World's largest bacteria discovered in Guadeloupe mangroves

You can see it with the naked eye and pick it up with a pair of tweezers - not bad for a single bacteria.

Scientists say they have discovered the world's largest variety in the mangroves of Guadeloupe - and it puts its peers to shame.

At up to two centimetres (three-quarters of an inch), "Thiomargarita magnifica" is not only around 5,000 times bigger than most bacteria - it boasts a more complex structure, according to a study published in the journal Science on Thursday.

The discovery "shakes up a lot of knowledge" in microbiology, Olivier Gros, professor of biology at the University of the Antilles and co-author of the study, told AFP.

In his laboratory in the Caribbean island group city of Pointe-a-Pitre, he marvelled at a test tube containing strands that look like white eyelashes.

"At first I thought it was anything but a bacterium because something two centimetres (in size) just couldn't be one", he said.

The researcher first spotted the strange filaments in a patch of sulphur-rich mangrove sediment in 2009.

Techniques including electronic microscopy revealed it was a bacterial organism, but there was no guarantee it was a single cell.

Molecular biologist Silvina Gonzalez-Rizzo, from the same laboratory, found it belonged to the Thiomargarita family, a bacterial genus known to use sulphides to grow. And a researcher in Paris suggested they were indeed dealing with just one cell.

But a first attempt at publication in a scientific journal a few years later was aborted.

"We were told: 'This is interesting, but we lack the information to believe you'," Gros said, adding that they needed stronger images to provide proof.

Future research will have to determine if these characteristics are unique to Thiomargarita magnifica, or if they can be found in other species of bacteria, Gros said.