Urease activity in Streptococcus salivarius at low pH. Characterization of the Actinomyces naeslundii ureolysis and its role in bacterial aciduricity and capacity to modulate pH homeostasis. Microbiol Res. Analysis of urease expression in Actinomyces naeslundii WVU Infect Immun. Regulation of urease gene of Actinomyces naeslundii in biofilms in response to environmental factors.
Actinomyces georgiae sp. Actinomyces gerencseriae sp. Int J Syst Bacteriol. Emended description of Actinomyces naeslundii and descriptions of Actinomyces oris sp.
Int J Syst Evolution Microbiol. Distribution of oral Haemophilus species in dental plaque from a large adult population. Periodontal microbial ecology. Urease and dental plaque microbial profiles in children. Oral Microbiology. Edinburgh: Churchill Livingstone; Dental plaque pH and ureolytic activity in children and adults of a caries population.
Acta Odont Scand. Effect of periodontal therapy on prevention of gastric Helicobacter pylori recurrence: a systematic review and meta-analysis. J Clin Periodontol.
Download references. GD — contributed to design, planning and writing of the manuscript. HH- contributed to the clinical sampling, data calculations and revised the manuscript.
SB — planned and contributed to most of the laboratory work and revised the manuscript. AC — contributed to the conception, planning and design of the study and critically revised the manuscript. All authors have read and approved the manuscript. You can also search for this author in PubMed Google Scholar. The research was ethically approved by the Regional Ethical Review Board Dnr —14 in Gothenburg Sweden , and followed the ethical considerations of the Helsinki declaration.
Written informed consent was obtained from the participants prior to the study. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Reprints and Permissions. Rapid urease test RUT for evaluation of urease activity in oral bacteria in vitro and in supragingival dental plaque ex vivo. BMC Oral Health 18, 89 Download citation. Received : 06 March Accepted : 26 April Published : 18 May Anyone you share the following link with will be able to read this content:.
Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search all BMC articles Search. Download PDF. Abstract Background Urease is an enzyme produced by plaque bacteria hydrolysing urea from saliva and gingival exudate into ammonia in order to regulate the pH in the dental biofilm.
Results The strongest activity was registered for Staphylococcus epidermidis, Helicobacter pylori, Campylobacter ureolyticus and some strains of Haemophilus parainfluenzae , while known ureolytic species such as Streptococcus salivarius and Actinomyces naeslundii showed a weaker, variable and strain-dependent activity.
Conclusion The rapid urease test RUT in a micro-plate format can be used as a simple and rapid method to test urease activity in bacterial strains in vitro and as a chair-side method for testing urease activity in site-specific supragingival plaque samples ex vivo.
Background Urease is an enzyme that hydrolyses urea carbamide into ammonia and carbon dioxide and is produced by several bacterial species. Table 2 Reactions from the clinical oral isolates in the RUT method read after 1 h. Full size image. Discussion Urea agar or broth test has been used routinely in bacteriological laboratories to test bacterial strains for urease activity.
Conclusions This study evaluated the usefulness of a simple test Rapid urease test, RUT for the assessment and semi-quantification of the ureolytic activity in various bacterial species in vitro as well as in dental plaque samples ex vivo. Other human pathogens are urease-positive, and in many cases, urea hydrolysis is thought to have a role in the infectivity or persistence of the microorganisms.
In this context, although largely unexplored, the positive role of urease in microbial physiology Fig. Because of the facts that the human genome does not contain urease-encoding genes and that no human nickel-containing enzymes are known, urease was proposed as a potential therapeutic target [36] without taking into consideration all the positive aspects linked to the microbial ureases of the human microbiota.
In the GIT, many pathogens and commensals use similar strategies to overcome the challenges associated with this particular environment. Funding: The authors received no specific funding for this study. Overview Since the discovery of Helicobacter pylori , the urease activity of this bacterial pathogen has been identified as the key factor in infection and acid acclimation in the human stomach.
Urease: Multifunctional Roles in Microbial Physiology Urease and its substrate urea represent historically important milestones in early scientific investigation. Download: PPT. Figure 1. Schematic representation of the reaction catalyzed by microbial urease and the involvement of these enzymes in microbial physiology, human health, and disease. Perspectives Because of the facts that the human genome does not contain urease-encoding genes and that no human nickel-containing enzymes are known, urease was proposed as a potential therapeutic target [36] without taking into consideration all the positive aspects linked to the microbial ureases of the human microbiota.
References 1. Sumner JB The isolation and crystallization of the enzyme urease. J Biol Chem — View Article Google Scholar 2. A metalloenzyme.
A simple biological role for nickel? J American Chem Society — View Article Google Scholar 3. Adv Inorg Biochem 6: — View Article Google Scholar 4. Science — View Article Google Scholar 5.
Microbiol Rev — View Article Google Scholar 6. Mol Biol Rev — View Article Google Scholar 7. Appl Environ Microbiol — View Article Google Scholar 8. Microbiol — View Article Google Scholar 9. Such a feature is characteristic of pathogenic Staphylococcus strains. Staphylococcus leei isolated from biopsy material from gastritis patients was also ureolytic. Uropathogenic Staphylococcus saprophiticus is also capable of this activity [ 1 , 11 , 22 ].
Urease is observed in Helicobacter sp. Urease is an enzyme synthesized by pathogenic mycobacteria like Mycobacterium tuberculosis and Mycobacterium bovis [ 12 ].
It was observed that anaerobic clostridia are capable of urea hydrolysis. Even some strains of Vibrio parahaemolyticus , a species considered non-ureolytic, produce urease [ 14 ]. Another generally urease negative bacterial species is Escherichia coli. Among E. Urease is one of the major bacterial virulence factors during urinary tract infections caused by these bacteria [ 1 , 24 ].
A similar phenomenon was noted for uropathogenic Ureapasma urealyticum , Klebsiella spp. D2, Proteus penneri , Providencia stuartii and Morganella morganii [ 1 , 22 ]. Urease is a nickel-containing enzyme, which requires activity of a few additional proteins for acquisition of its hydrolytic properties. This process involves genes coding structural enzyme polypeptides as well as genes coding accessory proteins, located in a joint cluster [ 1 , 25 ].
Bacterial ureases are always multimeric enzymes composed of two or three different polypeptides [ 1 ]. These polypeptides are encoded by three structural genes: ureA , ureB and ureC respectively [ 28 ]. Such organization is characteristic of most pathogenic and environmental bacteria. Unique urease of Helicobacter sp. A smaller Helicobacter sp. Urease composed of two different polypeptides 21 kDa and 65 kDa was also identified in SL ureolytic coccoid strain isolated from stomach biopsy material.
This strain was related to Staphylococcus cohnii and Staphylococcus xylosus , which possess three urease subunits [ 34 ]. An active center of enzyme with two metal ions is located in the largest of structural subunits. In all ureases it is designed as UreC, except Helicobacter sp. Ureases are nickel-containing enzymes; however, for microaerophilic Helicobacter mustelae an iron-containing urease was revealed [ 23 ]. All bacterial ureases occur as inactive apoenzymes composed of three or two types of polypeptides coded by specific structural genes.
However, additional proteins, products of accessory genes are required for urease activation. In these bacteria a regulatory gene ureR is present see Fig. Its product is a urea inducible regulator controlling expression of remaining genes [ 1 ].
It may adopt two different conformations. Conformational conservatism of bacterial ureases. A - structure of H. Active ureases are heterooligomeric complexes. However, the number of particular structural subunits is always equal. Likewise, for Helicobacter sp. Urease from K. Amino- and carboxyl terminus of each subunit are free and they are able to bind additional compounds without disturbing the enzyme structure [ 1 ].
But Prochrorococcus marinus sp. Enzymes from Helicobacter sp. Then, four such trimers form a tetrahedral complex Fig. Scheme of structure of bacterial ureases. Domain organization is reported for A H. Probably, such a highly complex structure of H. Ureases are considered to be conservative enzymes. Among all Ure polypeptides from different bacterial species, the highest sequence similarities were observed between structural urease subunits from different sources.
Particularly stable are nickel ligands: histidines in K. Many sequential identities occurred in all amino acid sequences.
In bacteria causing human diseases, even not closely related, significant conservatism was noted Fig. Alignment of the amino acid sequence of urease flap fragment from pathogenic bacteria.
Alignment was performed by Clustal W 2. The structure of a flap region in ureases from different bacteria also possess similar conformation Fig. Bacterial pathogens shows different ureolytic activity. Methods for its detection, including techniques applied in disease diagnosis, are diverse.
Hydrolysis of urea is one of useful features in the bacteria identification. In a few infections caused by microbes, detection of this activity is essential to disease diagnosis. Numerous assays are available to determine urease activity as well as to analyze kinetic behavior of urease. Most of them are indirect and based on colorimetric detection of ammonia released during incubation with a buffered urea solution [ 53 ].
One of the first methods was detecting bacterial ureolytic activity based on the cultivation of microorganism on urea containing medium Christensen's urea medium [ 54 ]. This is the most popular qualitative method using for uropathogenes like Proteus sp. In case of this bacterial species, results may be obtained even after 4 h. A modification of Christensen technique allows reducing assay time [ 54 , 55 ].
Ureolytic activity is one of biomarkers employed to diagnose H. For diagnosis, invasive and noninvasive tests, depending on whether endoscopy is required or not, are applied. The most popular invasive test is a rapid urease test RUT that requires obtaining tissue samples. However, this method is inconvenient for patients and also incurs high costs [ 57 , 58 ]. It requires biopsy specimens from defined regions of the stomach. This material is placed on a urea-containing medium.
If bacteria are present in the specimen, the change of color resulted from alkalization of the medium is observed [ 59 ]. A urea breath test UBT is commonly used among noninvasive tests.
This method is simple, but its performance may be slightly complicated in case of very young children as well as patients with certain neurological disorders [ 49 , 50 60 ].
It involves oral administration of a nontoxic isotopically labeled C 14 or C 13 urea to a patient. Urea is hydrolyzed by H. Carbon dioxide is dissolved into blood and removed via lungs. Isotopes are detected in exhaled air. This is a test of choice in medical practice for detecting H.
There are also suggestions that a urea breath test may be applied for diagnosing tuberculosis [ 62 ]. Other methods are used mainly in scientific research. There are a lot of other methods based on detecting ammonia released by urease action, which can be determined by vacuum distillation, a microdiffusion, steam distillation and electroconductivity measurement [ 77 ].
Fourier Transform Infrared FTIR spectroscopy is a method raising a big hope for easy, quick and continuous detection of ureolytic activity. This technique constitutes a radically different approach to enzymatic activity determination. It is based on the measurement of molecular vibrations energy of functional groups in organic compounds. This makes FTIR spectroscopy a highly sensitive and reproducible method. Unlike the previously discussed methods, this technique enables continuous monitoring of enzymatic reaction by a simultaneous analysis of disappearance of substrate and the appearance of product.
However, substrate as well as product must have different spectra. FTIR spectroscopy also enables enzyme kinetics investigation [ 78 ]. This technique was also applied for urease activity investigations. Bands of absorbance characteristic of urea substrate and of bicarbonate product could be easily monitored in time intervals Fig. Spectra of the reaction mixture were recorded at several time intervals: 0, 10, 20 and 35 min, as indicated.
Bacterial ureases play a role in disease pathogenesis. They are connected with urinary stones occurrence and catheters blocking, pyelonephritis, ammonia encephalopathy, hepatic coma as well as gastritis.
At in vitro conditions, H. During infection, microorganisms have to pass through gastric acid before reaching the protective mucus layer. In these circumstances, a pathogen produces a large amount of urease which is not observed in other bacteria [ 80 ].
At low pH, enzymatic activity of H. This enzyme is also able to perform a more efficient hydrolysis of urea. This property may be due to mobility of the flap region, which is different than in K.
Due to the high activity of H. Moreover, live bacterial cells adsorb on the surface enzymes released upon other H. Ureolytic activity is essential for surviving M. Bacteria infect macrophages. They reside in phagosome, where alkalization due to ureolytic activity and subvert phagosome maturation takes place.
Additionally, urease activity enables bacterium to exist in the environment where nitrogen sources are limited to urea [ 81 ]. Ureolytic activity is useful in better surviving of bacteria also in case of uropathogenes. Urease facilitates urinary tract infection. Infection dose for ureolytic P. Urease activity raises pH of human urine, which allows precipitation of normally soluble polyvalent ions to struvite and carbonate apatite. These compounds aggregate around bacteria, forming urinary stones.
Urinary stones block urethra or catheters leading to acute bacteriuria [ 24 ]. The role of ureolytic activity in urinary stones formation was also showed for U. D2, P. Schoep et al. This observation was confirmed by investigations with urease-negative H. Moreover, also urease released from lyzed bacterial cells is capable of adsorption into the mucus layer [ 4 ]. Bacterial ureases affect host immune system cells.
Urease is a chemotactic factor for monocytes and neutrophils. Inflammatory reaction may also be initiated by adsorption of released enzyme into the mucus layer [ 4 ]. Induction of inflammatory reaction was also observed for Y.
Ability of bacterial UreB subunit to induce experimental reactive arthritis was revealed [ 1 , 84 ]. Sign up for our email newsletter.
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