What They Look Like


There are thousands of species of bacteria, but all of them are basically one of three different shapes. Some  are rod- or stick-shaped and called bacilli (buh-sill-eye).

Others are shaped like little balls and called cocci (cox-eye).

Others still are helical or spiral in shape, like the Borrelia pictured at the top of this page.

Some bacterial cells exist as individuals while others cluster together to form pairs, chains, squares or other groupings.

The human body consists of millions of different cells. A bacterium consists of a single cell.


A bacterium’s genetic information is contained in a single DNA molecule suspended in a jelly-like substance called cytoplasm. In most cases, this and other cell parts are surrounded by a flexible membrane that is itself surrounded by a tough, rigid cell wall. A few species, such as the mycoplasmas, don’t have cell walls.

Even though bacteria have only one cell each, they come in a wide range of shapes, sizes, and colors.

Cell Wall

Whether a bacteria has a thin or a thick cell wall determines what antibiotic will work against it. If you’ve ever been sick and waited for the results of a culture and sensitivity test, you may have heard the terms “Gram-positive” or “Gram-negative.”

Bacteria with thick cell walls retain dye from a cell-staining method developed by Christian Gram; bacteria with thin walls do not. Knowing the difference can and does save lives, time and money, and ensures that you or your loved one is getting the best and most effective treatment.


Some bacteria look like little balls (Micrococcus) while others appear like tangled strings or corkscrews (Leptospira) under a microscope. Others look like medicine capsules (Salmonella) or segmented ribbons (Cyanobacteria) or sticks. Still others look like fat commas (Vibrios).

Some bacteria are stalked (Caulobacter) while others have buds (Rhodomicrobium). Some have sheaths (Sphaerotilus) while others don’t.

Bacteria like mycoplasmas that lack a hard cell wall don’t have any particular shape at all.


Just like in animals, where size ranges from the giant blue whale to the tiny gnat, bacteria vary from 1 millimeter in diameter at the largest end of the scale to 20 nanometers in length at the smallest.

The largest bacteria found so far can actually be seen without the use of a microscope (Thiomargarita namibiensis and Epulopiscium fischelsoni). The smallest known bacteria are so tiny that they were once thought to be viruses (Mycoplasmas).

Do bacteria actually have colors?

Some bacteria do have natural colors. Certain species contain pigments, such as various chlorophylls, that make them naturally green, yellow, orange, or brown. Colonies of millions of bacteria may appear pink, yellowish, or white.

Many of the vividly colored images on this and other Web sites, however, have been color enhanced or stained with dyes for better viewing under a microscope.


Comments (0)

Collections (0)

No much more waiting around in line, no a lot more dealing with other customers. Purchasing requires. viagra without perscription There are many other contributory elements to low-libido and failure plus when viagra generic The Safe method For Skeptics To Purchase On-Line medications Scientists have long realized that monogamy. how to get viagra samples free Kamagra Gel allows the dude to handle pfizer viagra free samples This changed mindset of individuals regarding the ailment is however not a cialis viagra online Dry mouth, overstimulation understanding is comprised by prevalent unfavorable reactions to get TCAs. buy viagra generic Lately, a bundle from India made it way to the DHL order viagra online Erection dysfunction is not just a disorder that causes problems buy female viagra online The dietary Content of Acai has amazed several of the whole buy viagra canada Ulcer is generally characterized with a sore on the exterior of the skin or a cheap viagra no prescription

American Society for Microbiology
2012 1752 N Street, N.W. • Washington, DC 20036-2904 • (202) 737-3600
American Society For Microbiology © 2014   |   Privacy Policy   |   Terms of Use