Burkholderia

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 placed in the genus were transfers from Pseudomonas, on the basis of various biochemical tests.^[1][2]

Until recently, the genus Burkholderia was inclusive of all Paraburkholderia species.^[6] However, the genus Paraburkholderia is phylogenetically distinct, and can be distinguished from all Burkholderia species on the basis of molecular signatures that are uniquely found for each genus.^[7]

Taxonomy

Burkholderia species form a monophyletic group within the Burkholderiales order of the Betaproteobacteria.^[4] Currently, the 48 validly named species can be distinguished from related genera (i.e. Paraburkholderia) and all other bacteria by conserved signature indels in a variety of proteins.^[7] These indels represent exclusive common ancestry shared among all Burkholderia species.

The genus has three distinct

Recently, research in Burkholderia species has investigated a range of topics and characteristics including metabolomic response to antibiotics, contact-dependent interactions between bacterial communities, and genomic potential to yield beneficial products.[9]^[10][11]

In Burkholderia species, certain antibiotics such as trimethoprim has been shown to induce and upregulate a large amount of the metabolome, inducing over 100 silent secondary metabolite gene clusters in Burkholderia thailandensis.^[9] These global activators can be used as a source of investigation into how the metabolomes of pathogenic bacterial species respond to antibiotic stress and how bacterial species can vary in response to them.^[9] It has been shown that closely related cystic fibrosis-associated Burkholderia species respond to trimethoprim with differing levels of expression of various secondary metabolites, highlighting the personalized nature of metabolomics in related bacterial strains.^[12]

Research focused on interbacterial signaling using Burkholderia has shown that contact-dependent growth inhibition plays a significant role in mediating cell to cell communication specifically in B. thailandensis.^[10] In this interaction, cells release protein toxins to the surrounding environment, and only those with a corresponding protective protein (usually bacteria of the same strain) will not have its growth inhibited or die. Furthermore, recipient cells that have the corresponding protein then undergo changes to gene expression and phenotype that promotes community formation in the form of biofilms. This occurs even if the recipient cell was not of the same bacterial strain which highlights the importance of this system.^[10] The genes that encode the protein toxins and the rest of the contact-dependent inhibition system can become mobile in the form of a transposon that can transfer between cells and is critical to communal aspect of the system.^[13] Thus, contact-dependent signaling plays a significant role in bacterial self recognition and community formation.^[10][13]

Burkholderia species have been shown to be a potential source of beneficial products such as antimicrobials and biosurfactants.^[11][14] Along with the related genus Pseudomonas, Burkholderia can synthesize a particular class of biosurfactant called rhamnolipids. Rhamnolipids synthesized by Burkholderia have differing chemical characteristics (compared to those synthesized by Pseudomonas) and thus have the potential for novel applications.^[14][15]

Species

List of species:^[16]

See also

• MAEB RNA motif

References