Brucella suis

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A Microbial Biorealm page on the genus Brucella suis

Classification

Higher order taxa

Bacteria(Domain); Proteobacteria (Phylum); Alphaproteobacteria (Class); Rhizobiales (Order); Brucellaceae (family)

Species

NCBI: Taxonomy

Brucella suis

Description and significance

The genus Brucella belongs to the {alpha}2 subdivision of the proteobacteria4. The traditional classification of Brucella species is largely based on its preferred host.Brucella suis remains a major zoonosis in the world. It is a Gram-negative bacterium. Brucella suis can transmit to human through pigs, and there are several cases showing that it can also infect wild swine. The disease it causes, brucellosis, is believed to be known to human for more than 2000 years, being first described by the Romans. In 1887, a scientist named Bruce first isolated Brucella melitensis, another species of the genus Brucella, which transmits to humans through goats, sheep and camel 1.

Genome structure

The Brucella suis genome contains around 3.3 million (3315175 bp) base pairs distributed in two circular chromosomes 5. The entire genome of B. suis has been sequenced. It has 2.9 mega base pair in its primary annotation, which is consist of 3430 genes total 5, and there are 3366 protein coding genes, 55 tRNA genes and 9 rRNA genes 5. Although B.suis has not been found to contain plasmids naturally, it has been shown that they can easily accept broad-host-range plasmids 2. Studies shows that the host preferences between different species in genus Brucella are encoded in their genes. For example, the fundamental differences between the genomes of B. suis and B. melitensis, which causes brucellosis in goats, cattle, and human, are in genes coding for surface-exposed proteins and proteins that help transport compounds across the inner and outer membranes 6.

Cell structure and metabolism

B. suis is a Gram-negative bacterium. It measures about 06 to 1.5 μm by 0.5 to 0.7μm 2. Because it can not produce sspore and lacks capsule or flagella, B. suis are non-motile. The outer membranes contain a dominant lipopolysaccharide (LPS) component and three main groups of proteins 2. A Study has shown that B. suis’ lipopolysaccharide (LPS) O side chain has a dramatic impact on macrophage activation, and it is firmly linked to Brucella virulence 7. The metabolism of the B.suis is mainly oxidative, and they are aerobes 2. In labs, B.suis shows little action on carbohydrates in conventional media 2. B.suis has been shown to have 190 metabolic pathways, and 923 enzymatic reactions done by 807 enzymes; it also makes 726 compounds by its pathway 8. For the complete reactions and pathway of B.suis, please see Summary of Brucella suis for detail information.

Ecology

Brucellosis has remained a major zoonosis since ancient times. It can causes abortion in livestock, and this particular species can be transmitted through birds.

Pathology

Brucellosis can be transmitted through abrasions of the skin from handling the infected animals. In U.S. it occurs more frequently via inhaling the waste product of the animal1. Brucellosis causes abortions in other animals; however, in humans, it causes a variety of symptoms, such as fever, anorexia, asthenia, fatigue, arthralgias, spine and joint pain. Although the bacteria rarely attacks the nervous system, neuropsychiatric symptoms such as headache and depression are often observed 1.

Application to Biotechnology

Since it has ability to transmit to human through pigs and wild swine, B. suis was researched as a biological weapon during the Cold War era by both the U.S. and Soviet Union governments. Today it still posses a danger, especially that it can be used as a biological weapon for terrorism attack.

Current Research

The most recent studies by Ian T. Paulsen et al. reviews that B. suis and many other members of the genus Brucella are in fact very close in genomic sequences to several bacteria belonging to the Agrobacterium/Rhizobium, which grow symbiotically with plants 9. Furthermore, Paulsen says. “Brucella may have a more extensive lifestyle outside their hosts than previous thought” 9 and more over, the plant symbionts and animal pathogens may employ similar mechanisms to infect their respective hosts-forming a symbiosis in some cases and causing diseases in others, he added 9.

References

1. Al-Nassir, Wafa, MD; Lisgaris, Michelle V, MD; Salata, Robert A, MD: Brucellosis, Emedicine, http://www.emedicine.com/med/topic248.htm

2. Alton, G.G.; Frosyth, J.R.L.: Brucella. http://www.gsbs.utmb.edu/microbook/ch028.htm

3. Brucella suis, Tamonomy Brower: NCBI http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=29461&lvl=3&lin=f&keep=1&srchmode=1&unlock

4. Science Week. Medical Biology: on Brucellosis. 2005 Science Week http://scienceweek.com/2005/sw050909-5.htm

5. Brucellla suis 1330 Genome Page, TIGR CMR, The Institute for Genomic Research, 2006 http://cmr.tigr.org/tigr-scripts/CMR/GenomePage.cgi?org=gbr

6. Brian Hoyle, Brucella suis Genome Like Those of Several Plant, Animal Pathogens. American Society for Microbiology, 2003 http://www.asm.org/microbe/index.asp?bid=11789

7. Jimenez de Bagues MP, et al, Different responses of Macrophage to smooth and rough Brucella spp.: relationship to virulence. PubMed, NCBI 2004, http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15039375&dopt=Abstract

8. Kaipa, Pallavi et al Summary of Brucella suis, Strain 1330, version 11.0. SRI International, 2006. http://biocyc.org/BSUI204722/organism-summary?object=BSUI204722

9. Paulsen, Ian T. et al. The Brucella suis Genome Reveals Fundamental Similarities between Animal and Plant Pathogens and Symbionts. Proceedings for the National Academy of Sciences of the United States of America, Oct. 1, 2002 http://links.jstor.org/sici?sici=0027-8424(20021001)99%3A20%3C13148%3ATBSGRF%3E2.0.CO%3B2-K

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