June 27, 2022
From BBC News Brazil to London
A group of scientists has just announced the details of the largest bacterium ever found in nature. It is so large that it can be seen with the naked eye, without the need for a microscope.
With the evocative name of Thiomargarita magnifica, it looks like white lint and inhabits the mangroves of Guadalupe, an archipelago located in the southern Caribbean.
To get an idea of its size, this bacterium is more than 9,000 micrometers long (a micrometer is the unit of measurement equivalent to one thousandth of a millimeter), or it exceeds 0.9 centimeters.
“At first it makes us question even the use of ‘micro’ to describe these bacteria, since microbiology deals with things that we cannot see with the naked eye,” comments biologist Sylvia Maria Affonso Silva, from the Federal University of São Paulo (Unifesp).
The largest known bacteria reach a maximum of 750 micrometers. On average, these beings measure about 2 micrometers.
This therefore means that T. magnifica is twelve times larger than the largest bacterium – and up to 4,500 times longer than a “typical” microbe.
It would therefore be possible to line up 625,000 units of Escherichia coli, one of the microorganisms responsible for intestinal infections, on the surface of a single T. magnifica.
These findings “challenge traditional knowledge about bacterial cells,” the authors write.
The discovery, which saw the participation of researchers from several institutions, such as the Lawrence Berkeley National Laboratory, in the United States, and the University of the Antilles, in Guadeloupe, was published in the latest issue of the specialized journal Science.
It should be remembered here that bacteria are part of nature and not all of them are harmful to our health – T. magnifica does not seem to pose a threat and seems to be in balance in the environment in which it is found.
T. magnifica has been found near the falling leaves of trees located in the mangroves of the islands of Guadeloupe.
Scientists used various techniques and equipment to unravel the structure and metabolism of the new species.
From what has been observed, it belongs to a group known as sulfur bacteria.
Generally speaking, this means that these beings use sulphur, a chemical element present in abundance in these waters, to live and multiply.
“Bacteria are single-celled beings, made up of a single cell, which have the genetic material scattered throughout,” Silva explains.
In more complex organisms, DNA is stored inside the cell nucleus.
T. magnifica seems to be “halfway” between these two scenarios. Its more than 11,000 genes – three times the genetic code of other bacteria – are encapsulated in membranous structures.
“This differentiated genetic organization is something very interesting and attracts attention, because it seems to be at the transition between prokaryotic beings, like other bacteria, and eukaryotic beings, which are more complex,” Silva analyzes.
According to the scientists responsible for the discovery, this different configuration represents a “characteristic innovation of more complex cells”.
“It is possible that this unique spatial organization indicates a gain in complexity that could have allowed T. magnifica to overcome the size and volume limitations typically associated with bacteria”, analyze the authors in a press release.
However, it is not yet known why this new species has grown so large compared to its cousins.
“Why do these organisms have to be so long is another [question] intriguing and challenging,” says microbiologist Petra Anne Levin of Washington University in St. Louis, USA.
The expert signs a brief analysis of the discovery, also published in Science.
“Another, more philosophical question is whether T. magnifica represents the upper limit of the size of a bacterium,” she continues.
“That seems unlikely and, as the study itself illustrates, bacteria are infinitely adaptable and amazing – and should never be underestimated.”