Burkholderia pseudomallei

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A Microbial Biorealm page on the genus Burkholderia pseudomallei

Classification

Higher order taxa

Domain; Phylum; Class; Order; family

Bacteria; Proteobacteria; Beta Proteobacteria; Burkholderiales; Burkholderiaceae

Species

NCBI: Taxonomy

Burkholderia pseudomallei

Description and significance

Burkholderia pseudomallei is a gram-negative bacterium with dimensions 2-5μm in length and .4-.8μm in diameter in the shape of a rod. This bacterium is aerobic and has a flagellum that provides motility. It found in the soil and water and is endemic to Southeast Asia and Northern Australia. Its optimal growth occurs at the temperature of 40°C and a neutral or slightly acidic pH. Burkholderia pseudomallei is significant in its role of causing a disease known as melioidosis, which currently doesn’t have a vaccine.

Genome structure

The genome consists of two chromosomes and each has a different role. The lager chromosome made up of 4.07 megabase pairs contains genes that are essential for “housekeeping work” such as metabolism and cell growth. The other chromosome is made up of 3.17 megabase pairs and contains genes that are essential for adaptation and survival in different environments. Careful scrutiny of the two chromosomes indicates that they each gained genomic islands and possess double the amount of DNA normally present in other bacteria to better adapt to the environment in order to survive.

Cell structure and metabolism

Burkholderia pseudomallei can go through fermentation of sugars such as glucose, galactose, maltose, and starch without gas formation. Nevertheless, this aerobic bacterium expresses genes that code for metabolic pathways such as glycolysis, Krebs Cycle, and pentose phosphate pathways. However, it is important to note that there is a down regulation in genes that code for energy metabolism such as ATP-synthase and NADH-dehydrogenase enzymes. Nevertheless, the genes that code for alternative energy sources, such as ubiquinol oxidase, formate dehydrogenase and ferredoxin oxidoreductase were highly expressed. It is evident that these alternative pathways are essential for slow growth in the host.

Ecology

Pathology

Burkholderia pseudomallei is a human and animal pathogen and is the cause of melioidosis, which is a disease native to Southeast Asia and northern Australia. It releases exo and endo toxins but their role in instigating the symptoms of melioidosis is not yet fully understood. Nevertheless, infection is spread through ingestion or contact of bacteria onto open skin wounds or through the inhalation of the aerosolized Burkholderia pseudomallei. Melioidosis can be classified as acute or chronic depending on the incubation time before symptoms appear. Burkholderia pseudomallei mimics tuberculosis in its ability o lay dormant without showing any symptoms for years. Common symptoms include fever, formation of abscess on various parts of the body such as the brain, osteomyelitis, bacteremia and various diseases of the heart, kidney and lungs such as pneumonia. Burkholderia pseudomallei is thought to have biological warfare potential and its virulence is made evident by being listed as a “Category B agent” by the US centers for Disease Control.

Application to Biotechnology

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

Current Research

Through computer simulation, 312 essential genes are identified as possible drug targets for Burkholderia pseudomallei.

References

“Getting a Grip on the Great Mimicker”. Sanger Institute. 14th September 2004 (http://www.sanger.ac.uk/Info/Press/2004/040914.shtml)

“Genomic plasticity of the causative agent of melioidosis, Burkholderia pseudomallei”. Proceeding of the National Academy of Sciences of the U.S.A. 14 September 2004. (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15377794)

(http://en.wikipedia.org/wiki/Burkholderia_pseudomallei)

(http://en.wikipedia.org/wiki/Melioidosis)

Chan-Eng Chong, Boon-San Lim, Sheila Nathan, and Rahmah Mohamed. “In Silico analysis of Burkholderia pseudomallei genome sequence for potential drug targets”. In Silico Biology. 2006. (http://www.bioinfo.de/isb/2006/06/0031/)

Apichai Tuanyok, Marina Tom, John Dunbar, and Donald E. Woods. “Genome-Wide Expression Analysis of Burkholderia pseudomallei Infection in a Hamster Model of Acute Melioidosis”. American Society for Microbiology. 2006. (http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1594879)