Rhodococcus equi: Difference between revisions

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==Structure, Metabolism, and Life Cycle==
==Structure, Metabolism, and Life Cycle==
The ''Rhodococcus equi'' thrives on volatile organic acids, such as those found in manure [[#References | [3]]]. Its cell envelope consists of mycolic acids, polysaccharides, and glycolipids that form around a unique periplasmic space [[#References | [3]]]. This envelope is special because it is different from other gram-negative and gram-positive bacteria. It has a strong wall that acts as a barrier for hydrophilc molecules, but contains porins within the cell wall that help bring in the necessary molecules for life [[#References | [3]]]. It has been speculated that due to the mycolic acids in the cell wall, ''R. equi'' is able to resist many kinds of environmental stresses such as less available oxygen or high acidity [[#References | [3]]].  ''R. equi'' is able to degrade a wide variety of aromatic compounds [[#References | [4]]].
The ''Rhodococcus equi'' thrives on volatile organic acids, such as those found in manure [[#References | [3]]]. Its cell envelope consists of mycolic acids, polysaccharides, and glycolipids that form around a unique periplasmic space [[#References | [3]]]. This envelope is special because it is different from other gram-negative and gram-positive bacteria. It has a strong wall that acts as a barrier for hydrophilc molecules, but contains porins within the cell wall that help bring in the necessary molecules for life [[#References | [3]]]. It has been speculated that due to the mycolic acids in the cell wall, ''R. equi'' is able to resist many kinds of environmental stresses such as less available oxygen or high acidity [[#References | [3]]].  ''R. equi'' is able to degrade a wide variety of aromatic and organic compounds [[#References | [4]]]. They can survive in the soil for very long periods of time due to their ability to degrade different compounds, including but not limited to pollutants and metals [[#References | [4]]].  
 
Rhodococci metabolize an exceptionally large variety of organic compounds, particularly hydrophobic xenobiotics, so they have an important role in the global carbon cycle. Their assimilatory capacities have been accredited to their diversity of enzymatic activities as well as their mycolic acid surfactants (3). For example, Rhodococcus sp. strain RHA1 has the ability to aerobically degrade polychlorinated biphenyls (PCBs) through cometabolization by the bph pathway, which is responsible for the aerobic degradation of biphenyl. The bph pathway consists of four enzymatic activities which act sequentially to transform biphenyl to benzoate and 2-hydroxypenta-2,4-dienoate. For each of these four steps, RHA1 appears to possess multiple isozymes, including at least three bph-type ring-hydroxylating dioxygenases and at least seven different bph-type ring cleavage enzymes. While most of the genes of the upper bph pathway are placed on two of three large linear plasmids, pRHL1 (1,100 kb) and pRHL2 (450 kb), genes encoding related isozymes are distributed hroughout the 9.7-Mb genome. This strain utilizes benzoate and phthalate as sole sources of carbon and energy. The catabolism of benzoate and phthalate occurs by a branched ketoadipate pathway in Rhodococcus.


**what important molecules it produces (if any), does it have an interesting life cycle?
**what important molecules it produces (if any), does it have an interesting life cycle?

Revision as of 03:12, 22 July 2013

This student page has not been curated.

Classification

Bacteria; Actinobacteria; Actinobacteria; Actinobacteridae; Actinomycetales; Corynebacterineae; Nocardiaceae

Rhodococcus equi

NCBI: Taxonomy


These are stained, cytoplasmic bodies of R. equi within lung tissue. [2

Description and Significance

Rhodococcus equi, originally discovered in horses by Magnusson, is a pathogen that is known to be able to affect animals and humans [4]. R. equi is a gram-positive coccobacillus that has the ability of producing a red pigment. It is a non-motile bacteria from the phylum Actinobacteria that is also aerobic and non-sporulating [1]. R. equi is able to utilize carbon efficiently and is therefore important to the recycling of carbon in the soil [5]. Up until 1983, this bacteria was mostly found to infect animals such as horses and foals [1]. Now there are more cases being seen in humans, especially those who are immunocompromised such as patients with AIDS [5]. R. equi generally leads to subacute or chronic bronchopneumonia which can lead to mortality, especially if not treated in the early stages [3] [1]. Infections due to R. equi currently have a mortality rate of approximately 25% [1].

Structure, Metabolism, and Life Cycle

The Rhodococcus equi thrives on volatile organic acids, such as those found in manure [3]. Its cell envelope consists of mycolic acids, polysaccharides, and glycolipids that form around a unique periplasmic space [3]. This envelope is special because it is different from other gram-negative and gram-positive bacteria. It has a strong wall that acts as a barrier for hydrophilc molecules, but contains porins within the cell wall that help bring in the necessary molecules for life [3]. It has been speculated that due to the mycolic acids in the cell wall, R. equi is able to resist many kinds of environmental stresses such as less available oxygen or high acidity [3]. R. equi is able to degrade a wide variety of aromatic and organic compounds [4]. They can survive in the soil for very long periods of time due to their ability to degrade different compounds, including but not limited to pollutants and metals [4].

    • what important molecules it produces (if any), does it have an interesting life cycle?
Foals can contract deadly pneumonia from R. equi. (Photo: Anne M. Eberhardt)

Ecology and Pathogenesis

Natural habitat (soil, water, commensal of humans or animals?)
If relevant, how does this organism cause disease? Human, animal, or plant hosts? Important virulence factors, as well as patient symptoms.

References

[1] Kedlaya, Indira. 2013. "Rhodococcus equi". Medscape Reference: Drugs, Diseases and Pathogens. http://emedicine.medscape.com/article/235466-overview

[2] Kulich, Scott M., Pasculle, William A. 1998. "Final Diagnosis--Pneumonia, Hilar Lymphadenitis and Sepsis Secondary to Rhodococcus equi." UPMC Department of Pathology. http://path.upmc.edu/cases/case146/dx.html

[3] Meijer, W.G., Prescott, John F. 2004. "Rhodococcus equi". Veterinary Research-A Journal on Animal Infection and Epidemiology (35): 383-396. http://www.vetres-archive.org/file/Vet.Res._0928-4249_2004_35_4/Vet.Res._0928-4249_2004_35_4_ART0002.pdf

[4] Navarro-Llorens, Juana M. et al. 2005. "Phenylacetate Catabolism in Rhodococcus sp. Strain RHA1: a Central Pathway for Degradation of Aromatic Compounds." Journal of Bacteriology (187): 4497-4504. http://jb.asm.org/content/187/13/4497.full

[5] Prescott, John F. 1991. "Rhodococcus Equi: an Animal and Human Pathogen." Clinical Microbiology Reviews. 4 (1): 20-34. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC358176/pdf/cmr00042-0036.pdf


Author

Page authored by Mattie Hogg, student of Mandy Brosnahan, Instructor at the University of Minnesota-Twin Cities, MICB 3301/3303: Biology of Microorganisms.