According to Science magazine, scientists have discovered an enormous bacterium hiding in the mangrove forests of Grande-Terre in the Caribbean, which can be seen with the naked eye without the aid of a microscope.
A newly discovered bacterium can be up to 0.78 inches (2 cm) long. This image shows another bacterium with a similar long and slender shape. (Image credit: STEVE GSCHMEISSNER via Getty Images)
According to a description, this “single-celled organism” can reach lengths of up to 0.78 inches (2 cm) and resembles a slender thread. The bacterium contains all its DNA within a membrane-bound sac, unlike most bacteria, which have their genetic material floating freely within their cells. This characteristic not only distinguishes the newly discovered microorganism from other bacteria but also sets it apart from other prokaryotic organisms—a group of life forms with very small, simple cellular structures. This group includes organisms found in the domains Bacteria and Archaea.
In contrast to prokaryotes, eukaryotic organisms, such as animals, plants, and fungi, have more complex cells that contain a nucleus and other membrane-bound organelles. The newly discovered giant microbe blurs the line between prokaryotes and eukaryotes in that it carries its DNA in a membrane-bound sac and also possesses a large second sac filled with water, which accounts for over 70% of the total volume of the cell, Science reports.
This water-filled sac compresses all the contents within the cell against its outermost edge, which may facilitate the diffusion of life-sustaining molecules into the cell while allowing toxins to be expelled more easily, according to Science.
A large sulfur-reducing bacterium in the genus Thiomargarita possesses a similar water-filled sac, and based on this similarity, along with genetic analysis, researchers concluded that the newly discovered bacterium may belong to the same genus. They proposed that the giant bacterium be named T. magnifica.
Kazuhiro Takemoto, a computational biologist at Kyushu Institute of Technology, told Science that “the giant bacterium could be a missing link in the evolution of complex cells.”
Chris Greening, a microbiologist at Monash University who was not involved in the study, told Science, “Typically, bacteria are considered to be small, simple, ‘unresolved’ life forms—the so-called ‘protein sacs.’ But this bacterium shows that this could not be further from the truth.”
