The Virtual Museum of Bacteria

Images of Bacteria

Written by Dr. T. M. Wassenaar Tuesday, 23 December 2008

The 'exhibits' of our museum contain text only. This enables easy access for every visitor. Not everybody has the fastest of computers. And we refrain from copying other people's pictures. But the beauty of bacteria becomes apparent first when you see them.

There are different ways of looking at bacteria. Bacteria growing in a liquid will generally make the liquid cloudy, and sometimes change color, but by the look of such a broth it is hard to determine what type of bacteria are growing in it.

More typically, bacteria are plated out on dishes filled with a solidified medium. Agar (a polycarbohydrate similar to gelatin) is usually used to produce a solid medium plate, called a 'Petri dish' (who was Richard Julius Petri?). The colors of the plates vary with the media used, but the growth can have bright colors, too, or change the color of the plates. See why 'color lovers' admire bacteria.  Bacteria are put on and care is taken to spread them out so thin that single cells cover the plate. Each of these cells will grow into  a colony.  How to produce single colony streaks.  The morphology (shape, color, shine, etc.) of colonies is often characteristic of the bacterial family or species.

Look at colony morphology at the following sites:

• Different colony types are clearly visible from an ocean sponge sample
• Artistry of bacterial colonies
  
• How to interprete colonies on an agar plate
• This website in antibiotics shows some beautiful examples of agar plates of both bacteria and molds - the latter ones are real masters of the Arts!
• Here's a pretty example of Streptomyces, plus a warning not to keep this in your fridge!
• YouTube  movie of growing bacteria, and here is another one
• Bacteriologists at work: different enteric bacteria on different agar plates. Learn why different agar plates are in use 

A special form of bacterial growth is biofilms. These films are a continuous layer of growing organisms and often contain different species. How does a biofilm form? More about Biofilms, presenting some Electronmicroscopic pictures.

For those of you who would like to do some experiments at home, ceck out our exhibit on do-it-yourself bacteriology (this link is currently inactive)

Sometimes scientists change the appearance of a bacterial colony on purpose. Introduction of a gene that produces Green Fluorescent Protein makes bacteria...green and fluorescent. (Source: Uni Cornell Uni Biomedical Engineering). When you add various fluorescent proteins, you can 'draw' with bacteria for fun! (Such E. coli bacteria expressing various fluorescent proteins are usually used for more serious science).

A bacteriologist will not only observe colonies on agar plates, but probably also look at the bacteria down a microscope. The color and appearance are sometimes manipulated by chemical stains, for instance the Gram Stain, which will differentiate gram-positive bacteria (the ones that stain deep purple) from the gram-negative ones. The Gram stain explained.

Listed below are the best picture galleries of Bacteria available on the web:

• Photo Gallery of pathogenic bacteria, an excellent collection site sorted by bacterial species.
• Cyonobacterial image gallery.
• Gram-stained images of medically important bacteria.
• Bacterial colonies and cell shapes.
• Photo Gallery of microorganisms (plus a few eukaryotic pictures)
• One of the best sites for pictures: Dennis Konkel Microscopy, which contains an extensive collection of electron-microscopic pictures, by bacterial species name or keywords.
• An Internet Gallery of bacteria.)
• Bacterial images sorted by species

Last Updated on Sunday, 01 March 2009