Burkholderia xenovorans

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A Microbial Biorealm page on the genus Burkholderia xenovorans

Classification

Higher order taxa

Bacteria; Proteobacteria; Betaprotobacteria; Burkholderiales; Burkholderiaceae; Burkholderia

Species

NCBI: Taxonomy

Genus species

Burkholderia xenovorans

Description and significance

Burkholderia xenovorans is an important aerobic degrader of polychlorinatred biphenyl (PCB), which is an organic chemical that has industrial use but is toxic to animals and humans. The LB400 strain is the most studied strain due to its ability to oxidize over 20 different PCB congeners. It was isolated in a landfill contaminated by PCB in New York over 20 years ago. Burkholderia xenovorans' environmental niche is in soil rhizospheres, which is the soil area surrounding plant roots.

Genome structure

The genome size of Burkholderia xenovorans varies between 7.4 to 9.3 Mbp, depending upon the particular strain. Burkholderia xenovorans has three circular replicons: chromosome 1 at 4.90 Mbp and chromosome 2 at 3.36 Mbp and a megaplasmid at 1.47 Mbp. Chromosome 1 contains homologs of dnaA (a chromosomal replication initiation protein) and dnaN (a DNA polymerase subunit). Chromosome 2 contains genes important for plasmid replication and partitioning, as well as other genes that help Burkholderia xenovorans adapt to it environmental niche. Unlike the chromosomes, the megaplasmid at 1.47 Mbp does not contain any essential functions or RNA.

Cell structure and metabolism

Burkholderia xenovorans is an aerobic gram-negative bacteria that is catalase- and oxidase-positive. The most interesting feature of Burkholderia xenovorans is its ability to catabolize aromatic compounds, such as those that come out of roots or involved in root turnover. Degradation of aromatic compounds usually involves an initial ring activation through either a hydroxylation by an oxygenase or a CoA ligase-mediated pathway. The aromatic compound then is shunted to one of several different catabolic pathways, depending on the substrate.

Burkholderia xenovorans contains nitrogen fixation genes, which are located on chromosome 2, which can be used to change elemental nitrogen. Burkholderia xenovorans also contains chemotaxis genes which allow it to move toward aromatic compounds in the soil rhizosphere.

Ecology

Burkholderia xenovorans' ability to fix nitrogen make it an important symbiont for plants to thrive in nitrogen-poor soil.

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Pathology

Burkholderia xenovorans is not known to cause any disease in humans or animals, and it lacks the genetic virulent features present in Burkholderia cenocepacia, which is an opportunistic pathogen in patients with cystic fibrosis and certain granulomatous diseases.

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research here--at least three required

References

Chain, P., Denef, V., Knstantinidis, K., et al. Burkholderia xenovorans LB400 harbors a multi-replicon, 9.73-Mbp genome shaped for versatility. Proc Natl Acad Sci U S A. 2006 October 17; 103(42): 15280–15287.

Petrucca A, Cipriani P, Sessa R, Teggi A, Pustorino R, Santapaola D, et al. Burkholderia cenocepacia vaginal infection in patient with smoldering myeloma and chronic hepatitis C. Emerg Infect Dis [1]. 2004 November.

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by student of Rachel Larsen