Sporosarcina pasteurii
Sporosarcina pasteurii is a bacterium which is able to break down the urea. It is one of the Firmicutes division. Due to the rod-shaped cells and the ability to produce endospores, it was assigned to the genus Bacillus in the past. Sporosarcina pasteurii is able to produce in certain culture media calcium carbonate, this makes them interesting for applications in biomineralization as a natural producer of cement.
- 5.1 Literature
- 5.2 Notes and references
Features
Appearance
The cells of Sporosarcina pasteurii are rod-shaped. They are gram- positive. The diameter of the cell is between 0.5 to 1.2 microns in width and from 1.3 to 4.0 micron in length. They occur singly or in pairs. S. pasteurii forms, like all species of the genus, endospores. The position of the spherical pores in the mother cell terminal, while the cell is not swelled. In light microscopic image it can be seen as bright, refractile forms. The species is motile, that can move independently.
Growth and metabolism
Sporosarcina pasteurii is heterotrophic, she does not perform photosynthesis. Metabolism is based on respiration and fermentation. The type is also under anaerobic conditions, ie the absence of oxygen, growth. The pH for best growth is pH 9 S. pasteurii is thus alkaliphilic, ie preferably high pH values . The optimum temperature for growth is 30 ° C. Furthermore S. pasteurii halotolerant and grows in a sodium chloride content of 10%. A liquid nutrient medium for the cultivation can be used, which also contains 2 % of urea or ammonium chloride, in addition peptone and yeast extract.
The urease test is positive, the type having the urease enzyme, and thus is capable of degrading urea in urine. From the genus Sporosarcina more types capable of urea (Latin urea ) to use, such as Sporosarcina ureae. Like all Sporosarcina species S. behaves pasteurii positive in catalase and oxidase test. Just as it is able to use gelatin hydrolysis, however, does not hydrolyze starch.
Of importance for applications in biomineralization is the fact that P. pasteurii calcium carbonate produced, called " biocement " (see cement) may be used. Responsible for this is firstly the enzyme urease, so p pasteurii urea can degrade using the urease. Process, the urea (NH2 -CO- NH2) under reaction with water ( H2O) 'split' is ( hydrolyzed), created it - in the alkaline pH, where she grows optimally - ammonium ions ( NH4 ) and carbonate ion:
When calcium ions are present in the nutrient medium, they react with the carbonate ions to form poorly soluble calcium carbonate:
The calcium carbonate is made as a precipitate from (synthetic calcium carbonate) or crystallized as calcite.
Chemotaxonomic features
The murein layer of the cell wall contains L-lysine as the diamino acid diagnostically important amino acid in position 3 of the peptide bridge. The peptidoglycan type is A4α ( an amino dicarboxylic acid - an amino acid with two carboxyl groups - connects two tetrapeptides ), at the amino dicarboxylic acid is D -aspartic acid. As is usual for Sporosarcina species is the major menaquinone MK- 7th The in the membrane lipids mainly occurring fatty acid, the branched fatty acid with the abbreviation anteiso - C15: 0 ( anteiso - pentadecanoic acid ), their share is 49 %. To 15% of the branched-chain fatty acid also comes with the abbreviation iso- C14: 0 in front (iso- octanoic acid ).
The GC content (the proportion of nucleobases guanine and cytosine) in the bacterial DNA is 38.5 mol percent. The genome of the bacterial strain S. pasteurii NCIM 2477 was completely sequenced in 2013, and published in 2014 as a draft (draft ). This is about the bacteria strain that is intensively researched because of the ability to biomineralization in order to possibly use it as a producer of " biocement " can. Previously, the nucleotides of the 16S rRNA for phylogenetic studies already determined, a typical representative for prokaryotes the ribosomal RNA.
Pathogenicity
Sporosarcina pasteurii is non-pathogenic ( " pathogenic " ), it is by the Biological Agents in connection with the TRBA (Technical Rules for Biological Agents ) assigned 466 Risk Group 1.
System
The type Sporosarcina pasteurii belongs to the family of Planococcaceae. This family will be provided to the Department of Firmicutes. The species was first described by Miquel in 1889 in the study of fermentation processes for urea and ammonium and first performed as Urobacillus pasteurii. Further investigation of Chester in 1898 resulted in the assignment to the genus Bacillus as Bacillus pasteurii. The research results of Jung- Hoon Yoon et al 2001 led to the fact that several Bacillus species of the genus Sporosarcina were assigned, this also applies to p pasteurii to. The names Bacillus pasteurii and Urobacillus pasteurii be used as synonyms. The type strain is ATCC S. pasteurii 11859th We do numerous bacterial strains of S. pasteurii in various collections of microorganisms.
Etymology
The genus name Sporosarcina derives from the Greek word spora ( " Spore " ) and the Latin word sarcina ( " bundle " ) and refers to the appearance of this spore-forming bacteria. The species name S. pasteurii has been chosen in honor of Louis Pasteur.
Occurrence and significance
The species was found in water, wastewater, soils and urinals.
Sporosarcina pasteurii is one of the microorganisms, the biomineralization is intensively studied to provide technical applications, based on their ability to produce calcium carbonate. Advantageous here is the high activity of the urease formed during substrate removal, whereby a large amount of calcium carbonate can be formed as a biomineral, when sufficient calcium ions are present in the nutrient medium. It is equally important that S. pasteurii as alkali -philic organism tolerates necessary for the biomineralization high pH values .
Suitable mixtures of S. pasteurii in nutrient media can serve as a sealant for cracks and gaps both in buildings and in natural limestone formations. Even the environmentally friendly production of cement ( " biocement " ) is possible. Furthermore, the use is made in the restoration of brick buildings and in the renovation of concrete in question. Also, the biomedical application is discussed.
Studies have shown that as a culture medium, a waste product from dairies is suitable, these are the so-called lactose mother liquor ( lactose mother liquor, abbreviated LML ). This is a liquid which remains in the separation of lactose and calcium ions derived from milk in a mass concentration of 353 mg / l (milligrams per liter) containing. LML thus represents a convenient alternative to conventional culture media to obtain a mortar-like component together with sterilized sand after inoculation with S. pasteurii. In a mixture of urease activity of 353 U / ml is determined (U - Enzymes unit - is the unit for the catalytic activity). The ausgekittete by the bacterium material consists of 24% of calcite. Also generated by irradiation with UV light mutants of a bacterial strain. The as Bp M-3 (Bp as an abbreviation for Bacillus pasteurii ) designated mutant shows in comparison with the wild type, the highest urease activity and produces most calcite.
Tests were performed in 2013 to connect by means of bricks S. pasteurii a masonry. In this case, a culture medium ( OptU ) is used which allows an optimal production of urease. In addition to glucose, yeast extract and urea, this medium contains magnesium sulfate ( MgSO4 · 7 H2O ), nickel (II ) sulfate ( NiSO4 · 6H 2 O ), calcium chloride (CaCl2 ) as well as buffer substances or dipotassium hydrogen phosphate ( K2HPO4 ) and potassium dihydrogen phosphate ( KH2PO4 ). Together with the bacteria contained ( the strain S. pasteurii NCIM 2477 ), it is used as a kind of mortar, in which the bricks are immersed. During the 28-day curing various parameters such as pH, urea degradation and calcite were monitored. In addition, it was investigated how the biomineralization on the water absorption capacity and the compressive strength effect. Treated with the nutrient medium OptU bricks, in comparison to those with an ordinary culture medium (nutrient broth ) treated better results, that is, a higher compressive strength and a lower water absorption. Based on these results is desired, such as in the repair or shoring of brick makers in commercial use. The restoration of cracks in the brickwork of historic buildings should be possible in this way, for example, the use of enriched bacteria with cement mortar during renovation of monuments.
In 2001, the concrete blocks were prepared from the cement mortar, which contained either the Portland cement S. pasteurii bacteria or offset in which cracks were filled with the bacteria in a nutrient medium. In the drawings, the mixtures with a rather small number of cells, the best results in terms of compressive strength. The repaired with bacterial material concrete blocks show an increased value for the compressive strength and the flexural rigidity.