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*

Taking Pudilan Xiaoyan Oral Liquid as a demonstration, the effective delivery of quality markers in alcohol precipitation of Chinese medicine oral liquid preparations was studied. With the transfer rates of adenosine, corynoline, cichoric acid, baicalin, and wogonin as evaluation indexes, the effect of the density of concentrate before alcoholic precipitation, volume fraction of ethanol, stirring speed, temperature of concentrated solution, stirring time, alcohol concentration, alcohol precipitation time, alcoholic precipitation temperature, alcohol addition rate, and the pH of concentrate on the alcohol precipitation process was investigated by Plackett-Burman trial design, thus obtaining the key factors that influenced the alcohol precipitation process. The key factors were further optimized by Box-Behnken design to determine the optimal alcohol precipitation conditions. When the density of concentrate before alcoholic precipitation was 1.12 g·mL~(-1), the pH of concentrate was 6.86, and the alcohol concentration was 50.00%, the transfer rates of baicalin and wogonin were 91.86% and 87.78%, respectively. When the density of concentrate before alcoholic precipitation was 1.13 g·mL~(-1), the concentration of alcohol was 74.50%, and the alcoholic precipitation temperature was 17.0 ℃, the transfer rates of adenosine, corynoline, and cichoric acid were 85.95%, 71.62% and 83.19%, respectively. The method of optimizing alcohol precipitation techniques and determining the parameters of Pudilan Xiaoyan Oral Liquid by response surface methodology is reasonable and feasible, which provides guidance and experience for the effective delivery of quality markers in Chinese medicine oral liquid preparations.
Drugs, Chinese Herbal ; Ethanol ; Adenosine ; Chemical Precipitation

To obtain ginsenoside Rg1 molecularly imprinted polymer (MIP) separating materials with high selectivity, enrichment and adsorption performance through directional separation of ginsenoside Rg1 and analogues. In this study, MIPs were respectively prepared by precipitation polymerization and surface imprinted polymerization. Their adsorption performances were compared. The results showed that ginsenoside Rg1 MIPs prepared by the above two methods had a high adsorption performance to template molecules, with the maximum apparent adsorbing capacity of up to 27.74, 46. 80 mg x g(-1), respectively. Moreover, MIPs prepared by surface imprinted polymerization showed higher adsorption capacity than that by precipitation polymerization. The experimental results indicated that as for ginsenoside Rg1 with higher polarity, MIPs prepared by surface imprinted polymerization showed higher selectivity and adsorption performance, which provides provide important reference for preparing imprinted polymers with good adsorption performance with active molecules with strong polarity.
Adsorption ; Chemical Fractionation ; methods ; Chemical Precipitation ; Ginsenosides ; chemistry ; isolation & purification ; Molecular Imprinting ; Polymerization ; Polymers ; chemical synthesis

Hydroxyapatite (HA) has been earmarked as suitable for implantation within the human of its chemical makeup to human bone. In this paper, HA powders were synthesized via the precipitation method where phosphoric acid (H3PO4) was titrated into calcium hydroxide solution [Ca(OH)2]. Two parameters such as temperature and stirring rate were identified as factors that influenced the amount and purity of HA powder. Phase identification of the synthesized powder was done using X-Ray Diffraction (XRD). The results show that HA phase can be synthesized from this titration process of Ca(OH)2 and H3PO4 with yield amount of HA powder around 45 - 61 grams but with less than hundred percent purity. In order to study the effect of heat treatment to HA crystals structure, HA powder was calcined at 850 degrees C for 2 hours. It's found that the degree of crystallinity increases after calcination because of lattice expansion when the materials were heated at higher temperature
Biocompatible Materials/*chemical synthesis ; Calcium Hydroxide ; Durapatite/*chemical synthesis ; Phosphoric Acids ; Precipitation ; X-Ray Diffraction

Astragalus polysaccharide has been widely used in food and medicinal industry owing to its health-promoting properties. In order to characterize better the relationship among molecular weight, structure-activity and activities, a simple method was used different concentration of ethanol including 30% (PW30), 50% (PW50), 70% (PW70), 75% (PW75), 80% (PW80) and 90% (PW90) to precipitate Astragalus polysaccharides into different molecular weight. As a result, PW90 showed smooth surface and the strongest antioxidant activity among these six fractions (P < 0.05). In conclusion, graded ethanol precipitation was a simple method to separate Astragalus polysaccharides into different molecular weight with different antioxidant activity fractions.
Antioxidants ; pharmacology ; Astragalus Plant ; chemistry ; Chemical Precipitation ; Ethanol ; chemistry ; Polysaccharides ; chemistry ; pharmacology

OBJECTIVETo establish a method integrating multi-targets for determining critical process parameters of the manufacturing process of traditional Chinese medicine.

METHODThe ethanol precipitation process of Danhong injection was taken as an application case of the method established. Fractional factorial design of experiments were conducted. Mathematical models relating seven process parameters to ten targets in the ethanol precipitation process were established. Then the sums of the absolute values of the regression coefficients in the models were used to evaluate the criticality of process parameters.

RESULTWater content in the concentrate, ethanol concentration and ethanol consumption were identified as the critical process parameters.

CONCLUSIONThe method established can integrate multi-targets effectively for the evaluation of critical process parameters.

OBJECTIVEWater content in concentrated extract (WCCE), the concentration of ethanol used in precipitation (CEA) and the quantity of ethanol added( QEA) are three important variables in the first ethanol precipitation of Danshen injection. In this work, the relationships between the three variables and total solid removal, Danshensu (DSS)retention and DSS purity were investigated.

METHODExperiments according to central composite design were carried out and mathematical models were developed.

RESULTThe models were accurate and predictive. The relative deviations between prediction results and experimental results were less than 3%. The influences of the three variables were discussed with a response surface method. The decrease of WCCE and the increase of CEA both caused more precipitation and increase the purity of DSS. However, more loss of DSS was observed. The increase of QEA increased total solid removal. DSS retention and DSS purity increased first and then decreased when QEA increased.

CONCLUSIONThis result suggests the addition of ethanol should be optimized according to WCCE and CEA to obtain better supernatant

Polyelectrolyte with a large number of cations or anions could precipitate the oppositely charged proteins to form polyelectrolyte-protein complexes, which then aggregated to form larger particles via electrostatic attraction or hydrophobic interaction. The precipitation was affected by the molecular weight and concentration of the polyelectrolyte as well as the ionic strength and pH of the solution. The use of precipitation is an efficient method for selective separation of proteins from crude biological mixtures in the downstream processes of bioengineering.
Acrylic Resins ; chemistry ; Chemical Precipitation ; Electrolytes ; chemistry ; Polyethyleneimine ; chemistry ; Protein Binding ; Proteins ; isolation & purification

Tetraselmis subcordiformis, a marine green alga, can produce hydrogen by photobiologically hydrolyzing seawater with hydrogenase. In this study, the preliminary purification of the enzyme was explored by ammonium sulfate precipitation, and the impact of sodium dithionite, beta-mercaptoethanol and glycerol on the enzyme stability during the process was investigated. The experimental results illustrated that sodium dithionite provided significant protection on the hydrogenase by depleting oxygen, while glycerol, a protectant against the structure instability of the enzyme, also presented protection. Crude enzyme with specific activity of 0.557 U/mg protein was extracted using 60%-70% saturated ammonium sulfate solution supplemented with 200 mmol/L sodium dithionite and 5% glycerol, and the hydrogenase recovery yield was about 30%.
Ammonium Sulfate ; chemistry ; Chemical Precipitation ; Chlorophyta ; enzymology ; Enzyme Stability ; Hydrogen ; metabolism ; Hydrogenase ; isolation & purification ; metabolism ; Seawater

OBJECTIVETo investigate the optimal alcohol precipitation parameters for extract of Carthamus tinctorius.

METHODSThe effects of different factors on the transfer rate of hydroxy safflower yellow A (HSYA) was studied via single factor experiments, including the final alcohol concentration of the liquor, the speed of stirring, the initial density of the extract, the temperature and the pH of the liquor. Based on the results of single factor experiments, the final alcohol concentration of the liquor, the speed of stirring, the initial density of the extract and the pH of the liquor were studied by an orthogonal test and a multiple guidelines grading method, and the transfer rate of HSYA, the yield and the purity of extract in the supernatant were used as comprehensive evaluation index.

RESULTThe optimal alcohol precipitation process of Carthamus tinctorius extract was as follows: the final alcohol concentration of the liquor 50%, the speed of stirring 500 r/min, the initial density of the extract 1.15 g/ml and the pH of the liquor 5.0.

CONCLUSIONThe proposed alcohol precipitation process is convenient and steady with high transfer rate of HSYA, high yield and purity of extract in the supernatant.