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Trudy Wassenaar

has published a book about - what else? - bacteria, describing them in all their microscopic grandeur.  In case you enjoy your visit of this virtual museum, you might also like to read this  book - in real life (as a printed book) or in the virtual world: the book is available for eReader, too.

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What are bacteria?

Bacteria are living things that are neither plants nor animals, but belong to a group all by themselves. They are very small -- individually not more than one single cell -- and those cells are even smaller than our own body cells. However there are normally millions of them together, for they can multiply really fast.

Bacteria are prokaryotes which means they are single cells that do not contain a nucleus. It may seem weird to classify organisms according to such details, but having or not having a nucleus is not trivial at all. The division between prokaryotes and eukaryotes (the latter are all organisms with a nucleus inside their cells) is of extreme importance in biology. Having a nucleus in your cells is the result of a major evolutionary breakthrough. Visit our other exhibits if you want to know more about bacteria and evolution, or in what extreme environments bacteria can be found.

Microbiology is the study of prokaryotes, eukaryotes (as long as the organism is microscopically small) and viruses.  What is the difference between bacteria and viruses?. Bacteria can be bad or good - it all depends on their kind. Did you know that bacteria can be ill too? In our museum Bacteria are in the center of the picture, but there also are many other micro-organisms that can be useful to mankind or cause infectious diseases. Here's explained what other micro-orgnisms exist that are not included in our museum. The exhibit bacteria and our senses explains how we can be aware of bacteria. And where are the pictures of bacteria? You need a microscope to view single bacteria, but if there are enough of them growing together, we can see their masses with bare eyes. In our display on Images of Bacteria it is explained why pictures are not included in our museum.

Bacteriology is the study of bacteria. Read more about bacteriology, which is a discipline of biology, in another exhibit. Bacteria can be used for 1001 applications. A few examples are given in our display on applied microbiology. That bacteria occpy a niche in every ecosystem where they live is explained in our Special Feature File on microbial ecology.

A number of bacteria cause disease, and because of that they are called pathogenic bacteria. They are the subject of Medical Microbiology and the exhibit pathogens deals with them. A separate exhibit explains about bacteria and food safety. Fortunately our immunesystem is well equipped to deal with most pathogenic bacteria we encounter on a daily basis. An infection is the exception, not the rule, although we meet pathogenic bacteria every day. However, not all bacteria are 'bad guys'. We need bacteria to stay alive, as is explained in our exhibit commensals.

(By now you may have discovered that the source of each external link is shown when you move your mouse over a link; if no source is given it means the link leads to another exhibit within our museum)

A brief synopsis of the diverse world of bacteria, where you can learn that not all bacteria are harmful, is found in this Nature Bulletins display. Another very informative site to visit is the Bacteria exhibit of the Museum of Paleontology, where you can also find a drawing and explanation of the inside of a typical bacteria. More details on bacterial structures are further explained in The New Microbial World, an introductory textbook for students of which the first 3 chapters are online.

  • If you're curious what real bacteria look like, don't forget to check out our Special Feature File: Images of bacteria.



Book recommendation

Wassenaar BacteriaBacteria: The Benign, the Bad, and the Beautiful

Dr. Trudy Wassenaar

Publisher's info


Missing Microbes: how the overuse of antibiotics is fueling our modern plagues - by Dr. Martin J. BlaserMissing Microbes: how the overuse of antibiotics is fueling our modern plagues

Dr. Martin J. Blaser

Publisher's info


Press release: An unusual job, by T.M. WassenaarPress release: An unusual job

Dr. Trudy Wassenaar

Publisher's info

Latest News

responsive webseitenThe Virtual Museum of Bacteria is now available on smartphone, tablet, iPhone and iPad.



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Mycobacterium lepraeDr. T. M. Wassenaar

View the organism:

Mycobacterium leprae under the microscope (D. Kunkel).


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