Bacillus (shape)
![](http://upload.wikimedia.org/wikipedia/commons/thumb/9/9f/Bacillus_species.jpg/250px-Bacillus_species.jpg)
A bacillus (plural bacilli) is a rod-shaped cylindrical bacterium.[1] Bacilli are found in many different taxonomic groups of bacteria.
- When the name Bacillus is capitalized and italicized, it refers to a specific genus of bacteria.[2]
There is no connection between the shape of a bacterium and its colors in the gram staining. In other words, some of them are gram negative and some are gram positive.