Microbial induced calcium carbonate precipitation (MICP) refers to the natural biological process of calcium carbonate precipitation induced by microbial metabolism in its surrounding environment. Based on the principles of MICP, microbial cement has been developed and has received widespread attention in the field of biology, civil engineering, and environment owing to the merits of environmental friendliness and economic competence. Urease and carbonic anhydrase are the key enzymes closely related to microbial cement. This review summarizes the genes, protein structures, regulatory mechanisms, engineering strains and mutual synergistic relationship of these two enzymes. The application of bioinformatics and synthetic biology is expected to develop biocement with a wide range of environmental adaptability and high performance, and will bring the MICP research to a new height.
Calcium Carbonate/metabolism* ; Chemical Precipitation ; Urease/metabolism*

Urease decomposes urea to ammonia, and has application potential in agriculture and medical treatment. Urease proteins include structural proteins (UreA, UreB and UreC) and accessory proteins (UreD/UreH, UreE, UreF and UreG), each of them has its own unique role in urease maturation. The structural proteins form the active center of urease, and the accessory proteins are responsible for the delivery of nickel. We review here the structure and function of bacterial urease complexes, and how each protein interacts to complete the activation process. We hope to provide theoretical basis for the regulation of urease activity and the development of urease inhibitors.
Bacterial Proteins ; Nickel ; Urease ; metabolism

Ethyl carbamate (EC) as a potential carcinogen commonly exists in traditional fermented foods. It is important eliminate urea that is the precursors of EC in many fermented foods, including Chinese Rice wine. On the basis of achieving high-level overexpression of food-grade ethanol-resistant acid urease, we studied the hydrolysis of urea and EC with the recombinant acid urease. Recombinant acid urease showed degraded urea in both the simulated system with ethanol and Chinese Rice wine (60 mg/L of urea was completely degraded within 25 h), indicating that the recombinant enzyme is suitable for the elimination of urea in Chinese Rice wine. Although recombinant acid urease also has degradation catalytic activity on EC, no obvious degradation of EC was observed. Further investigation results showed that the Km value for urea and EC of the recombinant acid urease was 0.7147 mmol/L and 41.32 mmol/L, respectively. The results provided theoretical foundation for realizing simultaneous degradation of urea and EC.
Oryza ; Recombinant Proteins ; metabolism ; Urea ; chemistry ; Urease ; metabolism ; Urethane ; chemistry ; Wine ; analysis

We tested correlations between anti-Helicobacter pylori IgG and IgA levels and the urease test, anti-CagA protein antibody, degree of gastritis, and age. In total, 509 children (0-15 years) were enrolled. Subjects were stratified as 0-4 years (n = 132), 5-9 years (n = 274), and 10-15 years (n = 103) and subjected to the urease test, histopathology, ELISA, and western blot using whole-cell lysates of H. pylori strain 51. The positivity rate in the urease test (P = 0.003), the degree of chronic gastritis (P = 0.021), and H. pylori infiltration (P < 0.001) increased with age. The median titer for anti-H. pylori IgG was 732.5 IU/mL at 0-4 years, 689.0 IU/mL at 5-9 years, and 966.0 IU/mL at 10-15 years (P < 0.001); the median titer for anti-H. pylori IgA was 61.0 IU/mL at 0-4 years, 63.5 IU/mL at 5-9 years, and 75.0 IU/mL at 10-15 years (P < 0.001). The CagA-positivity rate was 26.5% at 0-4 years, 36.5% at 5-9 years, and 46.6% at 10-15 years for IgG (P = 0.036), and 11.3% at 0-4 years, 18.6% at 5-9 years, and 23.3% at 10-15 years for IgA (P < 0.001). Anti-H. pylori IgG and IgA titers increased with the urease test grade, chronic gastritis degree, active gastritis, and H. pylori infiltration. Presence of CagA-positivity is well correlated with a high urease test grade and high anti-H. pylori IgG/IgA levels.
Adolescent ; Antibodies, Bacterial/*blood ; Antigens, Bacterial/*analysis/immunology ; Bacterial Proteins/*analysis/immunology/metabolism ; Blotting, Western ; Child ; Child, Preschool ; Chronic Disease ; Enzyme-Linked Immunosorbent Assay ; Female ; Gastritis/pathology ; Helicobacter Infections/blood/microbiology/*pathology ; Helicobacter pylori/isolation & purification/*metabolism ; Humans ; Immunoglobulin A/*blood ; Immunoglobulin G/*blood ; Infant ; Infant, Newborn ; Male ; Severity of Illness Index ; Urease/metabolism

Field experiments were conducted in Shangluo pharmaceutical base in Shaanxi province to study the effect of nitrogen, phosphorus and potassium in different fertilization levels on Platycodon grandiflorum soil microorganism and activities of soil enzyme, using three-factor D-saturation optimal design with random block design. The results showed that N0P2K2, N2P2K0, N3P1K3 and N3P3K1 increased the amount of bacteria in 0-20 cm of soil compared with N0P0K0 by 144.34%, 39.25%, 37.17%, 53.58%, respectively. The amount of bacteria in 2040 cm of soil of N3P1K3 increased by 163.77%, N0P0K3 increased the amount of soil actinomycetes significantly by 192.11%, while other treatments had no significant effect. N2P0K2 and N3P1K3 increased the amounts of fungus significantly in 0-20 cm of soil compared with N0P0K0, increased by 35.27% and 92.21%, respectively. N3P0K0 increased the amounts of fungus significantly in 20-40 cm of soil by 165.35%, while other treatments had no significant effect. All treatments decrease soil catalase activity significantly in 0-20 cm of soil except for N2P0K2, and while N2P2K0 and NPK increased catalase activity significantly in 2040 cm of soil. Fertilization regime increased invertase activity significantly in 2040 cm of soil, and decreased phosphatase activity inordinately in 0-20 cm of soil, while increased phosphatase activity in 2040 cm of soil other than N1P3K3. N3P0K0, N0P0K3, N2P0K2, N2P2K0 and NPK increased soil urease activity significantly in 0-20 cm of soil compared with N0P0K0 by 18.22%, 14.87%,17.84%, 27.88%, 24.54%, respectively. Fertilization regime increased soil urease activity significantly in 2040 cm of soil other than N0P2K2.
Bacteria ; enzymology ; growth & development ; isolation & purification ; metabolism ; Bacterial Proteins ; analysis ; metabolism ; Catalase ; analysis ; metabolism ; Fertilizers ; analysis ; Fungal Proteins ; analysis ; metabolism ; Fungi ; enzymology ; growth & development ; isolation & purification ; metabolism ; Nitrogen ; metabolism ; Phosphoric Monoester Hydrolases ; analysis ; metabolism ; Phosphorus ; metabolism ; Potassium ; metabolism ; Soil ; chemistry ; Soil Microbiology ; Urease ; analysis ; metabolism

Alkali production by oral bacteria is believed to have a major impact on oral microbial ecology and to be inhibitory to the initiation and progression of dental caries. A substantial body of evidence is beginning to accumulate that indicates the modulation of the alkalinogenic potential of dental biofilms may be a promising strategy for caries control. This brief review highlights recent progress toward understanding molecular genetic and physiologic aspects of important alkali-generating pathways in oral bacteria, and the role of alkali production in the ecology of dental biofilms in health and disease.
Agmatine ; metabolism ; Alkalies ; metabolism ; Arginine ; metabolism ; Dental Caries ; prevention & control ; Dental Plaque ; enzymology ; metabolism ; microbiology ; Humans ; Hydrogen-Ion Concentration ; Hydrolases ; metabolism ; Urease ; metabolism

OBJECTIVEThrough correlation and path analysis between total saponins content in rhizome/mycorrhizal infection rate in roots of Pairs polyphylla var. yunnanensis and soil factors, to make an inquiry into the role of soil factors in the quality formation of P. polyphylla var. yunnanensis.

METHODTested total saponins in rhizome, mycorrhizal fungal infection rate in root and physical and chemical properties in rhizosphere soil in 25 different growth areas, and statistically analyzed the relationship between total saponins in rhizome/mycorrhizal infection rate in roots of P. polyphylla var. yunnanensis and soil factors by using correlation and path analysis.

RESULTThe symbiosis relationship between AM mycorrhizal and roots of P. polyphylla var. yunnanensis were better established under natural condition, of which the infection ratio between 36.41%, 83.37%. There were significantly positive correlation between total saponins content in rhizome and urease activity or alkaline phosphatase activities or organic matter in soil, but there was significantly negative correlation between total saponins content and bulk density. There was significantly positive correlation between AM infection ratio and alkaline nitrogen. Path analysis indicated that total saponins of rhizome mainly affected by alkaline nitrogen in soil rhizosphere, secondly by soil organic matter and soil urease activity. While the mycorrhizal fungal colonization ratio was mainly affected by soil pH, secondly by alkaline nitrogen, urease activity, and available phospherus in soil.

CONCLUSIONThere is closed relationship between quality formation of P. polyphylla var. yunnanensis and soil factors. Path analysis is better for reflecting the contribution of soil factors to total saponins and mycorrhizal infection ratio.

Alkaline Phosphatase ; metabolism ; Liliaceae ; chemistry ; microbiology ; Mycorrhizae ; growth & development ; Rhizome ; chemistry ; Saponins ; analysis ; Soil ; analysis ; Urease ; metabolism

BACKGROUND/AIMS: In the Helicobacter pylori (H. Pylori)-negative normal stomach, collecting venules are visible over all the gastric body as numerous minute points evaluated with standard endoscopy. This finding was termed regular arrangement of collecting venules (RAC), and its absence suggests H. Pylori gastritis. The aim of this study was to evaluate the correlation between the RAC and rapid urease test. METHODS: Two hundred sixty three consecutive adults undergoing upper digestive endoscopy and rapid urease test were included. The lesser curvature of the lower corpus was evaluated for the RAC pattern using a standard endoscope and different hemoglobin index. Two biopsies from the lesser curvature of the antrum and the greater curvature of the body were collected for rapid urease test. RESULTS: H. Pylori were detected in 51.3% (135/263) patients. Of the 57 patients with H. Pylori-negative normal stomachs 53 patients (93%) had RAC. As a determinant of the normal stomach without H. Pylori infection, the presence of RAC had 41.4% sensitivity, 97.0% specificity, 93.0% positive predictive value and 63.6% negative predictive value. CONCLUSIONS: RAC-positive finding by standard endoscopy showed high positive predictive value and specificity of H. Pylori-negative normal stomach. RAC-positive finding by standard endoscopy could be an useful finding to predict H. Pylori negativity.
Adult ; Aged ; Diagnosis, Differential ; Endoscopy, Gastrointestinal ; Female ; Gastritis/microbiology/pathology ; Gastroscopy ; Helicobacter Infections/*diagnosis/microbiology ; *Helicobacter pylori ; Hemoglobins ; Humans ; Male ; Middle Aged ; Pyloric Antrum/blood supply/microbiology/pathology ; Retrospective Studies ; Sensitivity and Specificity ; Urease/metabolism ; Venules/anatomy & histology

PURPOSE: The role of the Ferric Uptake Regulator (FUR) in the acid resistance of Helicobacter pylori (H. pylori) has been thought to be independent of urease. However, we demonstrated in this study that Fur influences urease activity. MATERIALS AND METHODS: A fur knockout mutant of H. pylori was constructed by replacing the Fur gene with a kanamycin resistant marker gene. The wild-type H. pylori and fur mutant were compared for survival. The integrity of the inner membrane of the bacteria was evaluated by confocal microscopy using membrane-permeant and -impermeant fluorescent DNA probes. Urease activity of intact H. pylori was measured between pH 3 and 8. Real time PCR of both strains was performed for urease genes including ureI, ureE, ureF, ureG, and ureH. RESULTS: The fur deletion affected the survival of H. pylori at pH 4. The urease activity curve of the intact fur mutant showed the same shape as the wild-type but was 3-fold lower than the wild-type at a pH of less than 5. Real time PCR revealed that the expression of all genes was consistently down-regulated in the fur mutant. CONCLUSION: The results of this study showed that fur appears to be involved in acid resistant H. pylori urease activity.
Bacterial Proteins/genetics/*physiology ; Helicobacter pylori/*enzymology/genetics ; Hydrogen-Ion Concentration ; Microscopy, Confocal ; Models, Biological ; Mutation ; Repressor Proteins/genetics/*physiology ; Urease/*metabolism

Concanavalin A (ConA) is immobilized on a pre-activated chitosan microspheres, and then oriented immobilization of urease is carried out based on the strong interaction between ConA and glycoprotein. The optimum immobilization conditions are as follows: glutaraldehyde concentration is 3.5%, ConA concentration 1 mg/mL, ConA pH 7.0 and urease concentration 0.4 mg/mL. For orientedly immobilized urease, the highest activity was allowed at pH 5.0-6.0 and temperature 77 degrees C, and the Michaelis constant (Km) was disclosed to be 11.76 mmol/L by Lineweaver-Burk plot. Compared with the free urease and the randomly immobilized urease, the optimum pH of the orientedly immobilized urease becomes smaller and the pH domain wider. Orientedly immobilized urease presents higher temperature resistance, higher affinity to the substrate, and higher stability of operation.
Chitosan ; chemistry ; Concanavalin A ; chemistry ; Enzymes, Immobilized ; Glutaral ; chemistry ; Glycoproteins ; chemistry ; Hydrogen-Ion Concentration ; Microspheres ; Temperature ; Urease ; metabolism