Academics of the language are going to have work, because the definition of the word 'bacteria' has just been blown up. If we look in the current dictionary, we will see that it is defined as "microorganism" or "microbe", that is, a "unicellular organism only visible under a microscope". This explanation becomes obsolete with the discovery of a huge bacterium, almost one centimeter long, and visible without the need for any device. It is the first known bacterium that is not a microbe. the find is published this Thursday in the magazine Scienceafter a preprint of the discovery saw the light of day last February.
It is called 'Thiomargarita magnifica', it is larger than many animals, it has the appearance of whitish filaments and lives attached to sunken leaves of the mangroves of the Guadalupe archipelago, in the Caribbean.
These waters are sulphurous, that is, rich in sulfur from which a diverse bacterial population feeds. However, no variety is as large as the one discovered by marine microbiologist Jean-Marie Volland and his team.
How is it possible that a bacterium has reached such a size? The answer to this question lies, scientists believe, in its structure, which is unusually complex for a priori very simple creatures, because bacteria are unicellular beings (ie: each bacterium is a cell).
What sets T. magnifica apart from other bacteria, the authors report in a press release, is that instead of its DNA floating freely inside it, its genetic material is compartmentalized within membrane-bound structures, a innovation characteristic of more complex cells.
“These membrane-bound compartments are metabolically active and activity occurs throughout the length of the bacterial cell, rather than just at its growing end. It is possible that this unique spatial organization and membrane bioenergetic system, which indicate an increase in the complexity of its lineage, have allowed it to overcome the limitations related to size and volume that are usually associated with bacteria”, the authors add.
thousands of times greater
T. magnifica is thousands of times larger than common bacteria and about 50 times larger than other sulfur-eating bacteria, the largest known so far and called – ironically enough – 'giant bacteria' (despite the fact that they are only visible under a compound light microscope at 100 to 1,000x magnification).
Magnificent Thiomargarita unseats Thiomargarita namibiensis from the podium, described in 1999 and discovered in waters off the Skeleton Coast, Namibiaand that it was already about 100 times larger than the average for common bacteria.
In a commentary on this discovery, microbiologist Petra Anne Levin states that the finding "helps solve the puzzle of the factors that limit the size of cells" and adds: "Bacteria are infinitely adaptable, always surprising, and should never be underestimated”.
Levin leaves two questions up in the air. One is why these organisms 'need' to be so large. The other question is “of a more philosophical nature”, in his words. Namely: if T. magnifica represents the maximum size that a cell can reach.