Burkholderia


Burkholderia is a genus of Proteobacteria whose pathogenic members include the Burkholderia cepacia complex which attacks humans and Burkholderia mallei, responsible for glanders, a disease that occurs mostly in horses and related animals; Burkholderia pseudomallei, causative agent of melioidosis; and Burkholderia cepacia, an important pathogen of pulmonary infections in people with cystic fibrosis.
The Burkholderia genus name refers to a group of virtually ubiquitous Gram-negative, obligately aerobic, rod-shaped bacteria that are motile by means of single or multiple polar flagella, with the exception of Burkholderia mallei which is nonmotile. Members belonging to the genus do not produce sheaths or prosthecae and are able to utilize poly-beta-hydroxybutyrate for growth. The genus includes both animal and plant pathogens, as well as some environmentally important species. In particular, B. xenovorans is renowned for being catalase positive and its ability to degrade chlororganic pesticides and polychlorinated biphenyls. The conserved RNA structure Anti-hemB RNA motif is found in all known bacteria in this genus.
Due to their antibiotic resistance and the high mortality rate from their associated diseases, B. mallei and B. pseudomallei are considered to be potential biological warfare agents, targeting livestock and humans.

History

The genus was named after Walter H. Burkholder, plant pathologist at Cornell University. The first species to receive membership to the genus were transfers from the genus Pseudomonas, on the basis of various biochemical tests.
Until recently, the genus Burkholderia was inclusive of all Paraburkholderia species. However, the genus Paraburkholderia is phylogenetically distinct, and can be distinguished from all Burkholderia species on the premise of molecular signatures that are uniquely found for each genus.

Taxonomy

Burkholderia species form a monophyletic group within the Burkholderiales order of the Betaproteobacteria. There are currently 48 validly named species that can be distinguished from neighbouring genera and all other bacteria by conserved signature indels in a variety of proteins. These indels represent exclusive common ancestry shared among all Burkholderia species.
Within the genus, there are three distinct monophyletic clusters. One group consists of all species belonging to the Burkholderia cepacia complex, another clade comprises B. pseudomallei and closely related species, and the last clade encompasses of most of the phytogenic species within the genus, including B. glumae and B. gladioli . Conserved signature indels have also been discovered that are specific for each of these subgroups within the genus that aid in demarcating members of this extremely large and diverse genus.

Species

List of species: