The Largest Bacteria Ever Discovered

By: Adin Y. Blumofe  |  September 19, 2022

By Adin Y. Blumofe

In 1683, when the Dutch natural philosopher, Antonie van Leeuwenhoek, made the first modern microscope, he looked into a world never before viewed and ushered in the field of microbiology. His microscope allowed humans to see bacteria for the first time, but a recent discovery means humanity never needed a device to catch a glimpse of prokaryotes, in the first place.

Capable of being observed by the naked eye, a single-celled organism, 5000 times more prominent than the average microbe was recently discovered. Thiomargarita magnifica, the small behemoth, which can be “picked up with a pair of tweezers,” is proving to be biologically fascinating to scientists.

Traditionally, single-cell organisms, like bacteria, constrained by geometry, remain microscopic. Cells move resources in and waste out through their outer membrane, the phospholipid bilayer.  For a cell to enlarge it needs to increase the surface area of the phospholipid bilayer to keep up with greater resource demand and to flush out increased amounts of waste products. However, there is a fundamental problem: surface area is two-dimensional, while volume is three-dimensional. The mathematical implication is that the cell’s surface area will never expand faster than the size it needs to govern. In essence, cells become less efficient the larger they get. This is why cells usually divide instead of continuously expanding, as evolution favors the fittest. 

T. magnifica has bucked the trend of nature, resulting in a biological curiosity. Due to the bacteria’s enormous size, it unsurprisingly produces a tremendous amount of waste products that are stored in the central vacuole, a cell’s garbage bag, which occupies most of the organism’s volume. Normally, a bacteria’s ribosomes and DNA proliferate across the entirety of a bacteria, which are what keep the cell functioning. However, due to the immense size of the vacuole, the organelles are squeezed against the phospholipid bilayer, a most unusual arrangement.

The bacteria’s particular size has raised multiple questions that require further study and analysis. For instance, the species is “significantly above [the upper theoretical] limit” expected to be possible; current scientific assumptions in deriving these ranges now need to be reevaluated. Additionally, exactly why this species developed in the manner that it did remains a mystery. Currently, scientists do not believe the risk of cross commutability with humans or animals is possible. 

Thiomargarita magnifica is the largest microbe ever discovered, but we should assume it won’t always be the case. It has managed to elude researchers thus far partially because of its obscure location. It is found underwater, at “the border of seawater and sediment among mangroves” in the Caribbean. Humanity has named around 30,000 species of bacteria out of the estimated trillion that are thought to exist on our planet; a q-tip and curiosity are the only thing keeping Thiomargarita magnifica’s honorific status intact.