The Burkholderia cepacia complex (Bcc) comprises at least nine closely related species which can be correctly identified only by polyphasic taxonomic approaches. Members of the complex are among the most metabolically versatile microorganisms known as they grow on more than 200 organic compounds, fix N2 and carry multiple antibiotic resistances. They are involved in important processes such as biodegradation of pollutants, biocontrol of root diseases but some also cause disease in plants, animals and humans. Bcc strains are isolated from very different habitats, including soil, rhizospheres, streams and infected plants, animals and human tissues, especially lungs of cystic fibrosis (CF) patients. Bcc strains have large and plastic genomes comprised of multiple (2 to 4) replicons, which is thought to give them their ecological versatility.

Burkholderia cenocepacia is a Gram-negative bacterium which is ubiquitous in the environment and may cause a number of diseases in plants. Human infection can be caused by B.cenocepacia, especially in patients with CF and chronic granulomatous disease, and is often fatal. B.cenocepacia (strain AU1054) was recovered from the blood of a patient with CF. It is characterized as a representative of the B.cenocepacia PHDC clonal lineage. This clone appears to be widely distributed, having been found in CF patients in 24 US states and Europe, as well as in agricultural soil. Its genome consists of 3 chromosomes of 3.2 Mb, 2.6 Mb and 1.1 Mb (adapted from genome.jgi-psf.org/burca/burca.home.html).