Before the discovery of the new bacterium Thiomargarita magnifica, the bacterium Thiomargarita namibiensis, measuring just over half a millimeter, was considered the largest.
Mangrove forests are amazing ecosystems on the planet, distributed in equatorial and tropical zones. These trees are able to grow on the border between ocean and land, with their roots and trunks immersed in salt water. A team of researchers from the Laboratory for the Study of Complex Systems found a previously undescribed bacterium in the mangrove forests of Guadeloupe in the Caribbean Sea. Scientists did not immediately realize that it was a bacterium, since it was in the form of threads visible to the naked eye.
The bacterium was not only unusually large in size – up to two centimeters, but also had a structure uncharacteristic for prokaryotes: the cell was divided into two bags: the first contained DNA and ribosomes, and the second contained water. It is this water sac that most likely allows the bacteria to grow to such large sizes. In addition, the described bacterium had a very long genome – 11 million nucleotide pairs with 11,000 genes. Typically, the bacterial genome does not exceed 4 million base pairs and 4000 genes.
The study authors believe the discovery may force scientists to reconsider the characteristics that separate prokaryotes and eukaryotes. According to them, the described bacterium destroys the idea of prokaryotes as “the smallest, simple and undeveloped forms of life – bags with proteins inside.”