Pseudomonas
The basic tool which is used to classify Pseudomonas is the 16S rRNA gene.  However, it is hard to differentiate closely related Pseudomonas species, thus genes such as atpD, gyrB, rpoB, recA, and rpoD are also used in the taxonomy of Pseudomonas.Using gyrB and rpoD in phylogenetic analysis, Pseudomonas came from two predominant clusters; intrageneric cluster I (IGC I) and intrageneric cluster II (IGC II).