The world's largest bacteria has been discovered! It's bigger than a mosquito!

Review expert: Ji Shi Life Field Observer There are countless bacteria around us, but we cannot see them because the bacteria are very small. The diameter of most bacteria is between 0.5 and 5 μm. We can only see their true appearance under a microscope. However, recently scientists have discovered "giant bacteria" up to 2 cm long , which has changed people's understanding of the bacterial world.

The research was published in the journal Science

Source: science.org

Discovery of Thiomacaria ornate

Olivier Gros of the University of the French Andes discovered a strange white, long organism growing on the surface of the leaves of Flemish mangroves in the mangroves of the Guadeloupe Islands in the Caribbean. After five years of research, Jean-Marie Volland, a marine biologist at the Lawrence Berkeley National Laboratory in the United States, and his partners finally confirmed that this is actually a bacterium! It is the world's largest bacterium - Sulfotoma luxuriant .

White thiocarpus ornate, visible to the naked eye

Source: sciencemag.org

The discovery of Thiomargardum ornate is not the first giant bacterium discovered in human history, but it surpasses the Namibian Thiomargardum discovered by scientists in 1997. Namibian Thiomargardum and Thiomargardum belong to the same family of Thiomargardaceae, and its length reaches 0.75mm. Compared with ordinary bacteria, it is considered a "giant" among bacteria. At the same time, it has maintained the record of "the world's largest bacteria" for more than 20 years.

Colored micrograph of Thiomargaritum namibiae

Source: Wikipedia

Thiomargard can reach 2 centimeters in length, making it a "giant" in the bacterial world. It is 50 times the size of the largest known bacterium and 5,000 times the size of most bacteria. It is precisely because of this that the Date team did not consider it a bacterium before.

Comparison of giant bacteria and some other common microorganisms

Source: sciencemag.org

Thiomargard is a single bacterial cell with a filamentous appearance. Because it is white, it looks like a white "pasta".

Source: sciencemag.org

Thiomargard is a sulfur-oxidizing gammaproteobacterium that is not only the largest bacterium in history, but also the first and currently the only bacterium discovered to have its genetic material isolated in a eukaryotic manner.

Characteristics of bacteria

Although Thiomargard is large, it is still a bacterium, so let’s review the characteristics of bacteria here.

The main components of bacteria are cell membrane, cytoplasm, nucleoplasm and cell wall. Some bacteria also have special structures such as capsules, pili and flagella that other bacteria do not have.

Bacteria pattern diagram

Source: 59baike.com

Bacteria are prokaryotes, so they are usually single-celled and simple in structure, lacking cytoskeleton and membrane organelles. The most well-known examples are mitochondria and chloroplasts learned in biology textbooks in school. Bacteria are the largest group of microorganisms in terms of number and variety, including spirochetes, vibrio, spirochetes, actinomycetes, bacilli, cocci, mycoplasmas, rickettsia, and chlamydia.

The process of binary fission in prokaryotes, source | Wikipedia

Bacteria mainly reproduce by asexual binary fission . When the bacteria grow to a certain period, the nucleoid splits once to form two nucleoids of equal size and the new nucleus moves to both sides. Eventually, the cell is divided into two, and a new cell membrane is formed in the center of the original cell. And cell division is a continuous process. Some bacteria separate their daughter cells after division to form a single bacterial body, while others do not separate and form their own special arrangement, such as streptococci and streptobacilli.

Why is Thiomargard so big?

As early as the 1950s, American scientist Schechter and others discovered that the faster bacterial cells grow, the larger the cells. More importantly, the research broke new ground by using a mathematical formula to describe the relationship between bacterial size and growth rate, which means that as long as the cell growth rate is known, the cell size can be inferred relatively accurately.

Generally speaking, the larger the size of bacteria, the more difficult it is for nutrients to enter the cells, which largely limits the bacteria from becoming larger. Researchers believe that Sulfur Margaritifera can grow so large because it has more advanced cells and complex tissues, which increases its surface area and can therefore absorb more nutrients and energy. In addition, Sulfur Margaritifera can make good use of the chemical energy of sulfur in the sediments at the bottom of the sulfur-containing waters of mangroves, which is also one of the reasons why it is so huge.

The discovery of Thiomargard has overturned people's understanding of bacteria, but human beings have never stopped exploring the microscopic world. The road to human knowledge of and research on microorganisms is still long and arduous.