Pseudomonas - Classification History

Classification History

Like most bacteria genera the pseudomonad last common ancestor lived hundreds of millions of years ago. They were classified at the end of the 19th century.

Additionally, the etymology of the name was not provided and first appeared in the 7th edition of Bergey's manual (=top authority in bacterial nomeclature) as Greek pseudes (ψευδες) "false" and -monas (μονάς / μονάδα) "a single unit", which can mean false unit, but there is also the possibility that Migula intended it as false Monas, a nanoflagellate protist. Subsequently, the term "monad" was used in the early history of microbiology to denote single-celled organisms. Soon afterwards, species matching Migula's description were isolated from many natural niches and many were originally assigned to the genus.

New methodology and the inclusion of approaches based on the studies of conservative macromolecules have reclassified many strains.

Recently, 16S rRNA sequence analysis has redefined the taxonomy of many bacterial species. As a result, the genus Pseudomonas includes strains formerly classified in the genera Chryseomonas and Flavimonas. Other strains previously classified in the genus Pseudomonas are now classified in the genera Burkholderia and Ralstonia.

In the year 2000, the complete genome sequence of a Pseudomonas species was determined; more recently, the sequence of other strains have been determined, including P. aeruginosa strains PAO1 (2000), P. putida KT2440 (2002), P. protegens Pf-5 (2005), P. syringae pathovar tomato DC3000 (2003), P. syringae pathovar syringae B728a (2005), P. syringae pathovar phaseolica 1448A (2005), P. fluorescens PfO-1 and P. entomophila L48.

An article published in the journal Scientific American in 2008 showed Pseudomonas may be the most common nucleator of ice crystals in clouds, thereby being of utmost importance to the formation of snow and rain around the world.