Interesting Facts about Microorganisms

taenia saginata beef tapeworm
Taenia saginata (Beef tapeworm): CDC

Microorganisms are those living creatures that can not be viewed by the unaided eye, i.e., you need a microscope to view them. But some microorganisms can be seen without a microscope too. So in this blog post, I am presenting some of the unique and unbelievable facts about microorganisms I have compiled from various authentic sources.

Bacteria can be present virtually everywhere, from volcanic springs to arctic regions. The human mouth is home to more than 500 species of bacteria. Each square centimeter of your skin averages about 100,000 bacteria.

You are not alone.

Microorganisms are constantly associated with our body surfaces in a dynamic equilibrium. An average human contains about 30 trillion cells; the same individual may contain almost 100 trillion microbes. The bacteria and other microbes in our body outnumber our cells by about three to one. 

Largest Bacteria

Thiomargarita magnifica (facts of microorganisms)
This microscope photo provided by the Lawrence Berkeley National Laboratory in June 2022 shows part of a Thiomargarita magnifica bacteria cell. Université des Antilles via AP

Thiomargarita magnifica is the largest bacteria. Its threadlike single cell is visible to the naked eye. It is up to 2 cm in length and 500 times bigger than many other microorganisms. Unlike other bacteria, it has a huge genome that’s not free-floating inside the cell.

The second largest bacteria,Thiomargarita namibiensis, can also be seen without a microscope. Thiomargarita namibiensis <thigh-oh-mar-ger-ee-tuh nah-mih-bee-en-sis>, which means “sulfur pearl of Namibia,” is a single-celled giant bacteria that live in the ocean.

Longest Parasite

Beef tapeworm is the largest parasite (which causes taeniasis in humans), which can easily grow 7½ meters or 25 feet long! Imagine that living in your guts!

Smallest Bacteria

The smallest known bacteria are so tiny that they were once thought to be viruses (Mycoplasma).

Deinococcus radiodurans

 Deinococcus radiodurans withstand blasts of radiation 1,000 times greater than would kill a human being.

Oldest living Microbes

250 million-year-old bacteria spores have been revived.  In 2000, scientists said they had revived bacteria that had lain in suspended animation for 250 million years, encased in salt crystals deep in the earth.

Killer Disease

In 1918 more people died from the influenza virus (approximately 30 million) than in the first world war (10 million).

Half of the Oxygen Producers are Microbes

Microbes generate  at least half the oxygen we breathe.

Generation Time

If a single bacterium of 10-12  gram with a generation time of 20 min is continued to grow exponentially for 48 hours, it produces a population that weighs about 4000 times the weight of the earth.

Note: If you know other more exciting and unbelievable facts about microorganisms, please share them in the comment box below.


  1. Razin S. Mycoplasmas. In: Baron S, editor. Medical Microbiology. 4th edition. Galveston (TX): University of Texas Medical Branch at Galveston; 1996. Chapter 37. Available from: 
  2. Makarova, K. S., Aravind, L., Wolf, Y. I., Tatusov, R. L., Minton, K. W., Koonin, E. V., & Daly, M. J. (2001). Genome of the extremely radiation-resistant bacterium Deinococcus radiodurans viewed from the perspective of comparative genomics. Microbiology and molecular biology reviews : MMBR, 65(1), 44–79. 
  3. Sanderson, K. (2022). Largest bacterium ever found is surprisingly complex. Nature. 
  4. Centers for Disease Control and Prevention. (2023, June 6). CDC – Taeniasis. Centers for Disease Control and Prevention.  

Acharya Tankeshwar

Hello, thank you for visiting my blog. I am Tankeshwar Acharya. Blogging is my passion. As an asst. professor, I am teaching microbiology and immunology to medical and nursing students at PAHS, Nepal. I have been working as a microbiologist at Patan hospital for more than 10 years.

19 thoughts on “Interesting Facts about Microorganisms

  1. Bacteria can be found virtually everywhere, from volcanic springs to arctic regions. The human mouth is home to more than 500 species of bacteria. Each square centimeter of your skin averages about 100,000 bacteria.

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