What is the name of the largest known bacterium, discovered in 2022?

The largest known bacterium, discovered in 2022, is Thiomargarita magnifica. This sulfur-oxidizing bacterium was found on submerged red-mangrove leaves in Guadeloupe, in the Caribbean. Its filament-shaped cells average about 1 centimeter long, making them visible without a microscope—roughly the length of a human eyelash.

T. magnifica surprised scientists because bacteria are usually microscopic. Its enormous size is partly explained by a large central vacuole, which occupies most of the cell and pushes the cytoplasm toward the outside, reducing the distance nutrients must travel by diffusion. The cell also contains many copies of its genome.

Another unusual feature is its DNA storage. Instead of leaving genetic material freely dispersed through the cell, T. magnifica packages DNA inside membrane-bound compartments called pepins. The earlier record-holder, Thiomargarita namibiensis, remains scientifically important, but it was surpassed by T. magnifica. The name Thiomargarita means “sulfur pearl,” referring to sulfur granules that give its cells a pearly appearance.