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''Wallemia Sebi''
''Wallemia Sebi''
[[Image:Wallemia_sebi_conidiogenesis.jpeg|frame|right|150px|wallemia sebi reproduction (scale bar is 5um)]]


==Description and significance==
==Description and significance==
Rahnella aquatilis is a relatively rare gram-negative rod-shaped bacteria which has been found in fresh water, soil, certain animals such as snails [5] and certain beetles, [4] and isolated human clinical specimens. [2]  This bacterium is of importance because of its abundance and its disease-causing ability in humansMany different strains have been isolated, and presumably more will be disocvered.   
[3] W. sebi is one of three Wallemia species which are distinguished based on the size of the conidia formed and the extent of xerophilyIt is an asexual fungus that reproduces through conidiogenesisIts unique mode of conidiogenesis along with its strong ability to thrive without water are what sets Wallemia apart from other Basidiomycota.


==Genome structure==
==Genome structure==
As of the year 2000, at least 70 strains of Rahnella aquatilis have been identified [1]. According to the National Center for Biotechnology Information (NCBI), the whole genome has been sequenced for R. aquatilis Strain Y9602.  This particular strain has a genome consisting of 4,864,217 basepairs, with two identified plasmids [2]. Another strain, Rahnella aquatilis CUETM 77-115, was shown to have a genome consisting of 5,440,269 basepairs, and had a G-C content of 52.1% [3].
[1] W. sebi has a compact genome (9.8 Mb), with few repeats and the largest fraction of genes with functional domains compared with other Basidiomycota. [1] The genome has been completely sequenced to aid in the understanding of W. Sebi’s biology and ecology.


==Cell and colony structure==
==Cell and colony structure==
Rahnella aquatilis is gram-negative rod-shaped bacterium, about 2-3 microns in lengthStrain ISL 19 was isolated from soybean rhizosphere, and was seen to have several flagella for motility [6]. The bacterium can be readily cultured in the laboratory.  
[2] Forms small, raised aggregates that are tan in colorColonies grow best at 24˚C and [3] are very slow growing, reaching diameters between 3-6mm in 14 days. [2]The conidia produced mitotically; each is an exact replica of the parent.  They are cylindrical and measure between 1.5-2.5 lm in diameter.


==Metabolism==
==Metabolism==
Rahnella aquatilis is a facultative anaerobe (it can live in the absence or presence of oxygen) that fixes Nitrogen [2]R. aquatilis metabolizing whey lactose produces high levels of organic acids (except for lactic acid) [7].      
[2] Though little is known about its mode of fueling, W. Sebi is osmophilic which means that it prefers areas of high salt or sugar concentrationsAll fungi are heterotrophic and most are facultative anaerobes, so it is highly likely that W. sebi is as well.


==Ecology==
==Ecology==
Rahnella aquatilis is named so because of its prevalence in fresh water.  It has been found around the globe in places like the United States, Korea, Japan, Russia, the Ukraine, and Egypt. R. aquatilis has also been found in humans, soil, and snails [5]. One of the most unusual places for the the microbe to have been found was inside the gut of certain speicies of longicorn beetles in Korea [4].
[2]  W. Sebi is found in dry habitats like wood, hay, textiles, in crawl spaces, mattresses and human skin. It is among the most xerotolerant fungi, and because it can grow at water activity below .85, it is considered xerophilicWater activity (aw) is the unit of measurement used to describe the amount of water an organism requires for growth.  It is this property of fungi that causes dehydrated foods to become moldy, as many mold causing fungi are xerophilic.
 


==Pathology==
==Pathology==
Rahnella aquatilis is pathogenic in humans. The organism can be diagnosed in patients via blood cultures, respiratory washings, and in wound cultures.  Various infections, such as bacteremia (from renal infection), sepsis, respiratory infection, and urinary tract infection can be the resultOne case involved an 11-month-old girl with congenital heart disease who developed infective endocarditis [8]Another case involved a 76-year-old male who had prostatic hyperplasia presenting with acute pyelonephritis [9]. It is noted that R. aquatilis can potentially cause life-threatening infections in humans, infants and adults alike, especially the immunocompromised and organ transplant recipients.  Treatments have included intravenous and oral levofloxacin therapy (and other members of the quinolone family).
[2] W. Sebi has been found to cause hay fever symptoms which include coughing, sneezing, itchy and watery eyes, itchy nose, and sinus pressure.  W. Sebi has on rare occasions colonized human abscessesThere is one documented case of W. Sebi infecting an ulcer on the foot of a patient in northern IndiaThe patient was treated with an antifungal, itraconazole, but the patient neglected to attend follow up appointments so it is unknown if the treatment was successful. [3]
 


==References==
==References==
[1] J Chemother. 2000 Feb;12(1):30-9. <http://www.ncbi.nlm.nih.gov/pubmed/10768513>
[1] http://www.ncbi.nlm.nih.gov/pubmed/22326418; Padamsee M, Kumar TK, Riley R, Binder M, Boyd A, Calvo AM, Furukawa K, Hesse C, Hohmann S, James TY, LaButti K, Lapidus A, Lindquist E, Lucas S, Miller K, Shantappa S, Grigoriev IV, Hibbett DS, McLaughlin DJ, Spatafora JW, Aime MC. The genome of the xerotolerant mold Wallemia sebi reveals adaptations to osmotic stress and suggests cryptic sexual reproduction. Fungal Genet Biol. 2012 Mar;49(3):217-26doi: 10.1016/j.fgb.2012.01.007.  
[2] R.J. Martinez. J Bacteriol. 2012 Apr;194(8):2113-4. <http://www.ncbi.nlm.nih.gov/genome/?term=Rahnella%20aquatilis>
[3] Robert Martinez, University of Alabama. <http://genome.jgi-psf.org/rahac/rahac.info.html>
 
[4] Park, Doo-Sang, Hyun-Woo Oh, Won-Jin Jeong, et al. "A Culture-Based Study of the Bacterial Communities within the Guts
of Nine Longicorn Beetle Species and their Exo-enzyme Producing Properties
for Degrading Xylan and Pectin." The Journal of Microbiology, October 2007, p. 394-401.
 
[5] Brenner, Don J., Hans E. Muller, Arnold G. Steigerwalt, et al. "Two new Rahnella genomospecies that cannot
be phenotypically differentiated from Rahnella aquatilis." lnternstional Journal of Systematic Bacteriology (1 998), 48, 141 -149.
   
 
[6] Kim, Kil Yong, Diann Jordan, and Hari B. Krishnan. "Rahnella aquatilis, a bacterium isolated from soybean rhizosphere, can solubilize hydroxyapatite." FEMS Microbiology Letters Volume 153, Issue 2, 15 August 1997, Pages 273–277.


[7] Pintado, Manuela E., Ana I.E. Pintado, and F. Xavier Malcata. "Fate of Nitrogen During Metabolism of Whey Lactose by Rahnella aquatilis." Journal of Dairy Science, Volume 82, Issue 11, November 1999, Pages 2315-2326.
[2] http://web.bf.uni-lj.si/bi/biologija-mikroorganizmov/Publikacije/PDF%20datoteke/2005_ZdHSFGC.pdf.; Polona Zalar, G. Sybren de Hoog, Hans-Josef Schroers, John Michael Frank and Nina Gunde-Cimerman. Taxonomy and phylogeny of the xerophilic genus Wallemia (Wallemiomycetes and Wallemiales, cl. et ord. nov.). Antonie van Leeuwenhoek (2005) 87:311–328


[8] Matsukura H., Katayama K., Kitano N., et al. "Infective endocarditis caused by an unusual gram-negative rod, Rahnella aquatilis." Pediatric Cardiology, 1996 Mar-Apr; 17(2): 108-11.
[3] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2268330/; Guarro, J., H. C. Gugnani, N. Sood, R. Batra, E. Mayayo, J. Gene, and S. Kakkar. "Subcutaneous Phaeohyphomycosis Caused by Wallemia Sebi in an Immunocompetent Host." Journal of Clinical Microbiology 46.3 (2008): 1129-131. Web. 27 Apr. 2013.


[9] Tash, Kaley. "Rahnella aquatilis Bacteremia from a Suspected Urinary Source." Journal of Clinical Microbiology. May 2005, vol. 43 no. 5, 2526-2528.








Edited by Christopher John Connor, student of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio
Edited by Kyla Clark, student of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio

Latest revision as of 20:31, 2 May 2013

This student page has not been curated.

A Microbial Biorealm page on the genus Wallemia sebi

Classification

Higher order taxa

Domain (Fungi); Phylum (Basidiomycota); Class (Wallemiomycetes); Order (Wallemiales); Family (Wallemiacea); Genus (Wallemia)

Species

Species (Sebi)

Wallemia Sebi

wallemia sebi reproduction (scale bar is 5um)

Description and significance

[3] W. sebi is one of three Wallemia species which are distinguished based on the size of the conidia formed and the extent of xerophily. It is an asexual fungus that reproduces through conidiogenesis. Its unique mode of conidiogenesis along with its strong ability to thrive without water are what sets Wallemia apart from other Basidiomycota.

Genome structure

[1] W. sebi has a compact genome (9.8 Mb), with few repeats and the largest fraction of genes with functional domains compared with other Basidiomycota. [1] The genome has been completely sequenced to aid in the understanding of W. Sebi’s biology and ecology.

Cell and colony structure

[2] Forms small, raised aggregates that are tan in color. Colonies grow best at 24˚C and [3] are very slow growing, reaching diameters between 3-6mm in 14 days. [2]The conidia produced mitotically; each is an exact replica of the parent. They are cylindrical and measure between 1.5-2.5 lm in diameter.

Metabolism

[2] Though little is known about its mode of fueling, W. Sebi is osmophilic which means that it prefers areas of high salt or sugar concentrations. All fungi are heterotrophic and most are facultative anaerobes, so it is highly likely that W. sebi is as well.

Ecology

[2] W. Sebi is found in dry habitats like wood, hay, textiles, in crawl spaces, mattresses and human skin. It is among the most xerotolerant fungi, and because it can grow at water activity below .85, it is considered xerophilic. Water activity (aw) is the unit of measurement used to describe the amount of water an organism requires for growth. It is this property of fungi that causes dehydrated foods to become moldy, as many mold causing fungi are xerophilic.

Pathology

[2] W. Sebi has been found to cause hay fever symptoms which include coughing, sneezing, itchy and watery eyes, itchy nose, and sinus pressure. W. Sebi has on rare occasions colonized human abscesses. There is one documented case of W. Sebi infecting an ulcer on the foot of a patient in northern India. The patient was treated with an antifungal, itraconazole, but the patient neglected to attend follow up appointments so it is unknown if the treatment was successful. [3]

References

[1] http://www.ncbi.nlm.nih.gov/pubmed/22326418; Padamsee M, Kumar TK, Riley R, Binder M, Boyd A, Calvo AM, Furukawa K, Hesse C, Hohmann S, James TY, LaButti K, Lapidus A, Lindquist E, Lucas S, Miller K, Shantappa S, Grigoriev IV, Hibbett DS, McLaughlin DJ, Spatafora JW, Aime MC. The genome of the xerotolerant mold Wallemia sebi reveals adaptations to osmotic stress and suggests cryptic sexual reproduction. Fungal Genet Biol. 2012 Mar;49(3):217-26. doi: 10.1016/j.fgb.2012.01.007.

[2] http://web.bf.uni-lj.si/bi/biologija-mikroorganizmov/Publikacije/PDF%20datoteke/2005_ZdHSFGC.pdf.; Polona Zalar, G. Sybren de Hoog, Hans-Josef Schroers, John Michael Frank and Nina Gunde-Cimerman. Taxonomy and phylogeny of the xerophilic genus Wallemia (Wallemiomycetes and Wallemiales, cl. et ord. nov.). Antonie van Leeuwenhoek (2005) 87:311–328

[3] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2268330/; Guarro, J., H. C. Gugnani, N. Sood, R. Batra, E. Mayayo, J. Gene, and S. Kakkar. "Subcutaneous Phaeohyphomycosis Caused by Wallemia Sebi in an Immunocompetent Host." Journal of Clinical Microbiology 46.3 (2008): 1129-131. Web. 27 Apr. 2013.



Edited by Kyla Clark, student of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio