Sporosarcina ureae

Sporosarcina ureae
Scientific classification
Domain: Bacteria
Division: Firmicutes
Class: Bacilli
Order: Bacillales
Family: Planococcaceae
Genus: Sporosarcina
Species: Sporosarcina ureae
(Beijerinck 1901) Kluyver and van Niel 1936

Sporosarcina ureae is a type of bacteria of the genus Sporosarcina, and is closely related to the genus Bacillus. Sporosarcina ureae are aerobic, motile, spore-forming Gram-positive cocci, originally isolated in the early 20th century from soil.[1] S. ureae is distinguished by their ability to grow in relatively high concentrations of urea through production of at least one exo-urease, an enzyme that converts urea to ammonia.[2] Sporosarcina ureae has also been found to sporulate when environmental conditions become unfavorable, and can remain viable for up to a year .[1]

History

In the early 20th century, the famous Dutch microbiologist Martinus Beijerinck isolated a microorganism that he named Planosarcina ureae.[1] In an effort to isolate bacteria from urea containing soil enrichments, he repeatedly came across a motile coccus that clustered in packets and had the ability to form endospores. The isolated organism’s nomenclature changed often as the result of the morphological and biochemical observations done by early researchers.[1] In 1911, Lohnis proposed that the organism should be called Sarcina ureae because of the cluster packets the organism formed in culture. In the 1960s researchers MacDonald and MacDonald along with Kocur and Martinec moved Sarcina ureae to the genus Sporosarcina (proposed by Orla-Jensen in 1909 and first used by Kluyver and van Neil in 1936). Later in 1973, Pregerson isolated over 50 different strains of S. ureae from numerous soil samples around the world, finding that the organism is most commonly present in soils that reflected high activities of dogs and humans.[3]

Characteristics

The cells are coccoid. Cells are 1–2.5 μm. Cell division is carried out in two or three successive planes, such that tetrads or packets of eight or more cells are formed.[4] Sporosarcina ureae forms endospores (like all species of the genus). The endospores are 0.5–1.5 μm.[5] The species can move using a flagellum.

Metabolism

Sporosarcina ureae is heterotrophic, as it does not perform photosynthesis. Its metabolism is due to cellular respiration. The species is strictly aerobic, as it needs oxygen. The optimal pH for growth is 7. The optimal temperature for growth is 25 °C. Growth under oxygen exclusion is not performed. The oxidase test is positive.[5]

Ecology

Sporosarcina ureae is one of the bacteria that can make use of urea with the enzyme urease. Sporosarcina ureae is often found in soil. It forms the highest population densities in soils that are exposed to large amounts of urine, for example, cow pastures. Through plating serial dilutions of soil, both Gibson and Pregerson found that a gram of soil could contain up to 10,000 S. ureae organisms.[1] Sporosarcina ureae probably plays an important role in the degradation of urine. Sporosarcina ureae is also found in manure[6] and tolerates a pH of 9–10.[5]

Isolation

Over the years, several methods have been developed to isolate and maintain cultures of Sporosarcina ureae. In 1935, Gibson used standard nutrient agar supplemented with 3-5% urea to inhibit most other soil organisms that would otherwise outcompete S. ureae. Pregerson’s (1973) isolation technique was similar, however, she used tryptic soy yeast agar (27.5g Difco tryptic soy broth, 5.0g Difco yeast extract, 15.0g Difco agar, 1 liter of water) supplemented with 1% urea and incubated serial dilutions of soil samples at a cooler 22 °C. Omitting the urea provides an effective maintenance media.[3]

Etymology

The genus name derives from the Greek word spora ("spore") and the Latin word sarcina ("package", "bundle") and refers to the fact that it forms endospores and the typical arrangement of the cells.[5] The species name derives from the ability of this species to break down urea.[5]

Genetics and Phylogeny

Currently there exists only a draft genome of Sporosarcina ureae. Automated annotation server RAST (rast.nmpdr.org) reveals specific genes involved in stress response, cell wall and capsule, and household genes among others. Claus et al. (1983) determined the GC content of S.ureae to be 40.6-40.8%. S. ureae is closely related to other spore forming organisms of the Bacillus genus, an observation first noted by Beijerinck in 1903. Fox et. Al (1977) showed that S. ureae is most closely related to Bacillus pasteurii.[1]

Biotechnological Applications

Recently there has been increased interest in S. ureae due to the potential biotechnological applications; however, research has nearly been exclusively focused on the unique outer cell surface layer (S-layer). S-layers are composed of single proteins that form a predictable lattice structure and have potential applications in nanoelectronics, medicine, and biosensors. An example of this research is the S-layer’s promising role in enzyme immobilization. The process of artificially breaking down certain metabolites and poisons is often slowed by the proximity of the required enzymes needed to one another. However, if one were able to utilize the S. ureae S-layer, all the required enzymes needed to metabolize a specific poison could be bound together thus dramatically increasing rate of the reactions.[7] Furthermore, much of the research is looking into the self-assembly property of S-layers which, when bound to certain antibodies, has the ability to advance the vaccine development.[8] Studies are also looking its role in certain pathogens, such as Bacillus anthracies, where it is implicated in cellular attachment.[8]

Other important areas of this research is can be seen in some of the current work being done at the Ames Research Center (NASA), looking at organisms that convert urea to ammonium. A presentation by Lynn Rothschild (Horizon Lectures, Sept. 2012) indicated some of the first colonizers of Mars might use these organisms to convert human waste to ammonium and subsequently use the ammonium to lower the pH of the Mars soils in order to make calcium carbonate cement. This cement could then be used to make bricks and other building materials.

The ability for S.ureae to convert urea to ammonia has important potential applications in the production of biofuels and fertilizers. Ammonia is currently being actively researched as a carbon-alternative fuel source. The high octane rating (110-130) and its relative safety when compared to gasoline make it an ideal replacement to current gasoline. Traditional methods of generating ammonia for fertilizer rely heavily on the use of natural gas; in fact, it has been estimated that to produce the ammonia needed for current fertilizer demands accounts for 2% of the entire world’s energy consumption.[9]

References

  1. 1 2 3 4 5 6 Dworkin, Martin; Falkow, Stanley (2006). The Prokaryotes: Vol. 4: Bacteria: Firmicutes, Cyanobacteria. Springer. pp. 636–641.
  2. ↑ McCoy, D.D.; Cetin, A.; Hausinger, R.P. (1992). "Characterization of urease from Sporosarcina ureae". Archives of microbiology 157 (5): 411–416. doi:10.1007/bf00249097.
  3. 1 2 Pregerson, B.S. (1973). "The distribution and physiology Sporosarcina ureae". Master dissertation, California State University, Northridge.
  4. ↑ Madigan MT, Martinko JM (2006) (in German), Brock Mikrobiologie, ISBN 3-8273-7187-2
  5. 1 2 3 4 5 Paul Vos, George Garrity, Dorothy Jones, Noel R. Krieg, Wolfgang Ludwig, Fred A. Rainey, Karl-Heinz Schleifer, William B. Whitman (2009) (in German), Bergey’s Manual of Systematic Bacteriology: Volume 3: The Firmicutes, Springer, ISBN 978-0387950419
  6. ↑ Georg Fuchs (Hrsg.), Thomas Eitinger, Erwin Schneider; Begründet von Hans. G. Schlegel (2007) (in German), Allgemeine Mikrobiologie, Thieme, ISBN 3-13-444608-1
  7. ↑ Knobloch, D.; Ostermann, K.; Rödel, G. "Production, secretion, and cell surface display of recombinant Sporosarcina ureae S-layer fusion proteins in Bacillus megaterium". Applied and Environmental Microbiology 78 (2): 560–567. doi:10.1128/aem.06127-11.
  8. 1 2 Ilk, N.; Egelseer, E.M.; Sleytr, U.B. "S-layer fusion proteins—construction principles and applications". Current opinion in biotechnology 22 (6): 824–831. doi:10.1016/j.copbio.2011.05.510.
  9. ↑ Zamfirescu, C.; Dincer, I. (2009). "Ammonia as a green fuel and hydrogen source for vehicular applications". Fuel processing technology 90 (5): 729–737. doi:10.1016/j.fuproc.2009.02.004.
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