The genus Pseudomonas consists of Gram negative, non-fermentative straight or slightly curved rods.
Most species are motile.
Some species may use nitrate as a final electron acceptor. Some species are facultative chemolithotrophs, using H 2 or CO as energy sources. The genus Pseudomonas contains over sixty species, and a large battery of tests is necessary to identify all of them. We will concentrate on only three tests and four species. It is similar to phenol red media, but turns from green to yellow if the particular carbohydrate is used.