Removal Of Dextran Research Articles

Efficient removal of dextran in sugar juice by immobilized α-dextranase from Chaetomium gracile

Abstract Dextran problem restricts the development of the sugar industry. Although the enzymatic treatment based on α-dextranase from Chaetomium gracile (α-dextranase (CG)) has been effective in solving this issue, the lack of immobilization products hinder its industrial applications. This research described a novel and suitable method to immobilize α-dextranase (CG). The purified α-dextranase (CG) was immobilized via cross-linking using modified chitosan as carriers. In addition, this study used a deep eutectic solvent that greatly improved the enzymatic properties of immobilized α-dextranase (CG). α-dextranase (CG) was immobilized by adding deep eutectic solvent (DES-IM-α-dextranase (CG)) showed better temperature tolerance and storage properties than free and ordinary immobilized counterparts. It can eliminate dextran by 59.71% in mixed sugarcane juice and 38.71% in clarified sugarcane juice. The achieved results were considerably better than those obtained using free and other immobilized enzymes. Altogether, these findings confirmed that DES-IM-α-dextranase (CG) displayed great potential in solving the dextran problem.

Nanoparticle-Stabilized Emulsion Bioink for Digital Light Processing Based 3D Bioprinting of Porous Tissue Constructs.

A challenge for bioprinting tissue constructs is enabling the viability and functionality of encapsulated cells. Rationally designed bioink that can create appropriate biophysical cues shows great promise for overcoming such challenges. Here, a nanoparticle-stabilized emulsion bioink for direct fabrication of porous tissue constructs by digital light processing based 3D bioprinting technology is introduced. The emulsion bioink is integrated by the mixture of aqueous dextran microdroplets and gelatin methacryloyl solution and is further rendered stable by β-lactoglobulin nanoparticles. After bioprinting, the printed tissue constructs create the macroporous structure via removal of dextran, thereby providing favorable biophysical cues to promote the viability, proliferation, and spreading of the encapsulated cells. Moreover, a trachea-shaped construct containing chondrocytes is bioprinted and implanted in vivo. The results demonstrate that the generated macroporous construct is of benefit to cartilage tissue rebuilding. This work offers an advanced bioink for the fabrication of living tissue constructs by activating the cell behaviors and functions in situ and can lead to the development of 3D bioprinting.

Minimizing of Dextran during Sugar Beet Manufacturing

The most serious processing problem can clear arise from the presence of dextran gum. The presence of dextran in sugar processing leads to less of sucrose and creates problems to sugar producers by increasing viscosity, lowing sugar yield, increasing molasses purities slowing filtration. The application of dextran enzyme to reduce dextran from raw juice was more efficient and economic than adding it to clear juice and syrup. Sixty percent of dextran removal was achieved when dextranase applied at concentration of 20u/100ml raw juice and 30min incubation. The dextran reduction and reached 65% by the use of 30u under some condition in clear juice, the percentage of dextran reduction reached 25,27 and 45% when dextranase enzyme used at 30u /100mol after 10,20 and 30 min of the incubation respectively. The use of the application of dextranase enzyme to reduce dextran from raw juice was more efficient and economic than adding it to clear juice and syrup.
 Sixty percent of the dextran was removed when using dextranase applications at a concentration of 20u/100ml of raw juice over 30 minutes.

Removal of bacterial dextran in sugarcane juice by Talaromyces minioluteus dextranase expressed constitutively in Pichia pastoris

A gene construct encoding the mature region of Talaromyces minioluteus dextranase (EC 3.2.1.11) fused to the Saccharomyces cerevisiae SUC2 signal sequence was expressed in Pichia pastoris under the constitutive glyceraldehyde 3–phosphate dehydrogenase promoter (pGAP). The increase of the transgene dosage from one to two and four copies enhanced proportionally the extracellular yield of the recombinant enzyme (r-TmDEX) without inhibiting cell growth. The volumetric productivity of the four-copy clone in fed batch fermentation (51 h) using molasses as carbon source was 1706 U/L/h. The secreted N-glycosylated r-TmDEX was optimally active at pH 4.5–5.5 and temperature 50–60 °C. The addition of sucrose (600 g/L) as a stabilizer retained intact the r-TmDEX activity after 1-h incubation at 50–60 °C and pH 5.5. Bacterial dextran in deteriorated sugarcane juice was completely removed by applying a crude preparation of secreted r-TmDEX. The high yield of r-TmDEX in methanol-free cultures and the low cost of the fed batch fermentation make the P. pastoris pGAP-based expression system appropriate for the large scale production of dextranase and its use for dextran removal at sugar mills.

Tannin Extract for Sugarcane Juice Clarification

Clarification of sugarcane juice is one of the most important steps in the sugar manufacturing process, considering that an efficient clarification may result in highly beneficial effects on the quality and yield of the final product, crystal or refined sugar. Currently, depending on the industrial plant and intended product, the use of calcium hydroxide, phosphoric acid and sulfur dioxide as auxiliary agents for clarification has been consolidated, the latter being questioned for causing adverse health reactions. In this context, the present study evaluated the performance of the natural black Acacia (Acacia mearnsii) tannin extract as an alternative for the sugarcane juice clarification. The results showed that tannin dosages between 300 and 500 ppm along with liming applied at pH 7.3 and 3 ppm of anionic flocculant provided the best performance, resulting in 32–34% of color removal and 89–93% of turbidity removal. Under these conditions, starch and dextran removal increased, 90 and 98%, as compared to 69% and 96%, obtained with conventional treatment. The performance of the tannin also reduced the calcium hardness of clarified juice by up to 18% compared to the conventional treatment, which in turn may prevent fouling in the subsequent steps.

Hierarchically targetable polysaccharide-coated solid lipid nanoparticles as an oral chemo/thermotherapy delivery system for local treatment of colon cancer

Although oral formulations of anticancer chemotherapies are clinically available, the therapeutic action relies mostly on drug absorption, being inevitably accompanied with systemic side effects. It is thus desirable to develop oral therapy systems for the local treatment of colon cancers featured with highly selective delivery to cancer cells and minimized systemic drug absorption. The present study demonstrates the effective accumulation and cell uptake of the doxorubicin and superparamagnetic iron oxide nanoparticles-loaded solid lipid nanoparticle (SLN) delivery system for chemo/magnetothermal combination therapy at tumors by hierarchical targeting of folate (FA) and dextran coated on SLN surfaces in a sequential layer-by-layer manner. Both the in vitro and in vivo characterizations strongly confirmed that the dextran shells on SLN surfaces not only retarded the cellular transport of the FA-coated SLNs by the proton-coupled FA transporter on brush border membranes in small intestine, but also enhanced the particle residence in colon by specific association with dextranase. The enzymatic degradation and removal of dextran coating led to the exposure of the FA residues, thereby further facilitating the cellular-level targeting and uptake of the SLNs by the receptor-mediated endocytosis. The evaluation of the in vivo antitumor efficacy of the hierarchically targetable SLN therapy system by oral administration showed the effective inhibition of primary colon tumors and peritoneal metastasis in terms of the ascites volume and tumor nodule number and size, along with the absence of systemic side effects.

Water Flux Reduction in Microfiltration Membranes: A Pore Network Study

AbstractA 3D pore network model was developed to simulate the removal of dextran from water. Advanced scanning electron microscopy combined with focused ion beam analysis was used to obtain the sizes of the different pore networks that represent the microscopic structure of a porous membrane. The required input transport parameters for modeling were obtained by performing dynamic experiments on dextran adsorption within the pores of a polysulfone membrane. The simulated flux changes demonstrated a good agreement with the experimental data showing that such a model can be used to study the effects of various parameters during the process. Specifically, the results showed an increase in the applied pressure, decreased membrane thickness, increased pore size, while small sizes of contaminant molecules lead to a rise of the flux passing through the membrane.

Statistical tools application on dextranase production from Pochonia chlamydosporia (VC4) and its application on dextran removal from sugarcane juice.

The aim of this study was to optimize the dextranase production by fungus Pochonia chlamydosporia (VC4) and evaluate its activity in dextran reduction in sugarcane juice. The effects, over the P. chlamydosporia dextranase production, of different components from the culture medium were analyzed by Plackett-Burman design and central composite design. The response surface was utilized to determine the levels that, among the variables that influence dextranase production, provide higher production of these enzymes. The enzymatic effect on the removal of dextran present in sugarcane juice was also evaluated. It was observed that only NaNO3 and pH showed significant effect (p<0.05) over dextranase production and was determined that the levels which provided higher enzyme production were, respectively, 5 g/L and 5.5. The dextranases produced by fungus P. chlamydosporia reduced by 75% the dextran content of the sugarcane juice once treated for 12 hours, when compared to the control treatment.

Enhancement of Catalytic Performance of α-dextranase from Chaetomium gracile Through Optimization and Suitable Shear Force

Dextran causes negative impact on the normal production of sugar industry. Traditional removal methods have many disadvantages. 6-alpha-d-glucan-6-glucanohydrolase (EC 3.2.1.11) from Chaetomium gracile without food safety concern could remove dextran, but it has low level of enzyme production. The present study aimed to improve α-dextranase activity to meet industry demand. Consequently, α-dextranase activity reached 242.8 U/mL when fermentation condition was 29 °C, pH 6.0 and 220 rpm. Meanwhile, ten glass beads were added to fermentation medium when fermentation time was 12 h, which improved enzyme activity by 135.5% with the highest activity. Purified α-dextranase exhibited excellent thermal stability and surfactants tolerance. α-Dextranase from C. gracile could remove dextran by 46.6% in mixed sugarcane juice and 14.1% in clarified sugarcane juice. It had similar dextran removal efficiency with commercial enzymes. These evaluations showed that α-dextranase had great potential in removing dextran in sugar industry.

Improved Dextranase Production by Chaetomium gracile Through Optimization of Carbon Source and Fermentation Parameters

The fungus Chaetomium gracile is used for production of dextranase and removal of dextran during sugar manufacturing process, however, the productivity of dextranase is low. In this study, we investigated the influence of carbon source on dextranase production using dextrans of different sizes. Culturing C. gracile in medium containing crude dextran and use of high molecular weight of dextrans resulted in the higher yield of dextranase production (80.5 ± 4.0 U ml−1). Cells incubated in medium containing glucose as sole carbon source exhibited a high growth rate but did not produce dextranase. Based on these findings, fed-batch and two-step fermentation strategies were employed to further increase the yield of dextranase with production of 159.5 and 187.0 U ml−1, respectively.

Kinetic and Thermodynamic Properties of Partially Purified Dextranase from Paecilomyces lilacinus and Its Application in Dextran Removal from Cane Juice

Dextran is a high molecular weight polysaccharide formed in sugarcane during post harvest staling resulting in loss of sucrose as well as quality of sugar. Information regarding the removal of polysaccharides from the sugarcane milled juice is limited. In the present study, enzyme dextranase was produced from Paecilomyces lilacinus by submerged fermentation using Mandel medium and substrate dextran. The crude enzyme was partially purified by 80 % ammonium sulphate saturation followed by DEAE-cellulose column chromatography. Two isoforms of dextranase D-I and D-II each with optimum pH 5.0 and temperature 50 °C were identified. Both the isoforms were most efficient kinetically at pH 5.0 and temperature 50 °C and were found to be thermostable in the temperature range 0–50 °C. The pKa values of ionizing groups in free enzyme and enzyme-substrate complex were found to be between 4.1 and 5.8 indicating the possible participation of carboxylate groups of aspartate/ glutamate and imidazolium group of histidine in dextranase catalysed hydrolysis of dextran by both the isoforms. Activation energy (Ea) values for D-I and D-II were 22.07 and 31.68 kJ/mol and corresponding enthalpy change (ΔH) values were 17.01 and 8.70 kJ/mol, respectively. Cu2+ activated whereas Mg2+, Ca2+, Mn2+, Fe2+ and Pb2+ inhibited the activity of dextranase. With the application of 5, 10 and 15 units of partially purified dextranase per 100 mL of juice, dextran content decreased by 56.39, 73.88 and 80.27 %, respectively as compared to the control (with no dextranase added) after 24 h of storage of cane juice.

Impact of Dextranase on Sugar Manufacturing and its Kinetic on the Molecular Weights of Remaining Dextran

In this work, we investigated the influence of dextranase enzyme on the molecular weight parameters of remaining dextran and intrinsic viscosity after different enzymatic treatments at different steps during sugar manufacturing. A spectrophotometric method was used to determine the relative activity of dextranase and the result has been confirmed by measured reducing sugar using HPLC system. For comparison, the action patterns of concentrated and diluted enzymes were additionally included in the experiments. Addition of dextranase to juice were much more efficient and economical to reduce the Mw of remaining dextran than adding it to evaporator syrups. Addition of dextranase at juice pH 5.5 showed similar minimum Mw with the lowest intrinsic viscosity, observed at 55.0 °C, and activities decreased after 20°Brix. The highest dextran removal was observed at dextranase concentration at 100 ppm/juice which was resulted in 80.29 % removal dextran in the juice, Moreover, the higher the level of concentrated dextranase applied to the juice, the more the removal of dextran occurred. In addition, the longer the availability of the residence time in the factory, the lower dextran Mw has been observed. To reach a satisfactory level of dextran hydrolysis, it was necessary to correct the dose of dextranase enzyme according to the losses of activity caused by the high °Brix.

Biocatalytic potential of an alkalophilic and thermophilic dextranase as a remedial measure for dextran removal during sugar manufacture

The present study is focused on dextranase from Streptomyces sp. NK458 with potential to remove dextran formed during sugar manufacture. The dextranase had molecular weight of 130kDa and hydrolyzed 15–25 and 410kDa dextran. Dextranase production was optimized using statistical designs and the enzyme was purified 1.8-fold with 55.5% recovery. It displayed maximum activity at pH 9.0 and 60°C and was stable over a wide range of pH from 5.0 to 10.0. The km and Vmax values were 3.05mM and 17.97mmol/ml/h, respectively. Ten units of dextranase could reduce dextran content by 67% in 24h and 56% in 72h from sugarcane juice of cane variety CoS 86032. The enzyme was stable up to 3days at 30°C beyond which its activity decreased and dextran removal could be retained by supplementation of 5U of dextranase. These properties make it a promising biocatalyst for sugar industry.

Kinetics of model high molecular weight organic compounds biodegradation in soil aquifer treatment

Soil Aquifer Treatment (SAT) is a process where treated wastewater is purified during transport through unsaturated and saturated zones. Easily biodegradable compounds are rapidly removed in the unsaturated zone and the residual organic carbon is comprised of primarily high molecular weight compounds. This research focuses on flow in the saturated zone where flow conditions are predictable and high molecular weight compounds are degraded. Flow through the saturated zone was investigated with 4 reactors packed with 2 different particle sizes and operated at 4 different flow rates. The objective was to evaluate the kinetics of transformation for high molecular weight organics during SAT. Dextran was used as a model compound to eliminate the complexity associated with studying a mixture of high molecular weight organics. The hydrolysis products of dextran are easily degradable sugars. Batch experiments with media taken from the reactors were used to determine the distribution of microbial activity in the reactors. Zero-order kinetics were observed for the removal of dextran in batch experiments which is consistent with hydrolysis of high molecular weight organics where extracellular enzymes limit the substrate utilization rate. Biomass and microbial activity measurements demonstrated that the biomass was independent of position in the reactors. A Monod based substrate/biomass growth kinetic model predicted the performance of dextran removal in the reactors. The rate limiting step appears to be hydrolysis and the overall rate was not affected by surface area even though greater biomass accumulation occurred as the surface area decreased.

Dextran Removal by Plasmapheresis in a Kidney-Pancreas Transplant Recipient With Dextran 40–Induced Osmotic Nephrosis

Osmotic nephrosis with acute kidney injury can follow the administration of colloid volume expanders and other hypertonic solutions. In the kidney transplant setting, such agents may be used in the donor before organ procurement and in the recipient during the perioperative period. We report a case of acute lung and kidney injury after infusion of dextran 40 immediately after surgery in a kidney-pancreas transplant recipient. Osmotic nephrosis was confirmed by kidney biopsy, and a spectrophotometric assay was used to measure dextran 40 levels in serial serum samples. Plasmapheresis was initiated to decrease dextran 40 levels. Post hoc analysis confirmed that a single session of apheresis was sufficient to rapidly decrease dextran 40 levels without rebound, consistent with a small volume of distribution in a single-compartment model.

Dextranase production from Paecilomyces lilacinus and its application for dextran removal from sugarcane juice

Dextranase was produced from fungus Paecilomyces lilacinus by submerged fermentation under different cultural conditions viz. pH, incubation temperature, inoculum size and days of incubation for maximum enzyme production. Maximum enzyme production was achieved at pH 6.0 of Mandel media and at temperature 30°C. Inoculum size of 1 × 107 spores/ml was found to be optimum for maximum enzyme production. Enzyme production increased with the increase in days of incubation from 3 to 5 days and then declined thereafter. Dextranase units (from 1 to 15 U/100 ml juice) were exogenously added to sugarcane juice with an aim to optimize dextranase application for removal of dextran from cane juice. Addition of dextranase in juice of cane variety CoS 8436, resulted in relatively less increase in dextran content as compared to control during storage. Whereas, dextran content in untreated juice increased 10 times during 24 h of storage, the increase during this period was only 2.3 times in juice treated with 15 U of dextranase. With the application of 1, 2, 5, 10 and 15 units of dextranase in 100 ml of juice, dextran content was decreased by 15.51, 30.82, 50.20, 68.20 and 73.30 % as compared to the control (with no dextranase added) after 24 h of storage. This study finds application in minimizing the dextran problem in sugar industry.

Codon optimization to improve the production yield of recombinant human interferon α by Pichia pastoris

In this work we employ PEGylated polyethyleneimine (pPEI) o act both as an affinity ligand, to increase the selectivity of the ystem, and as a pDNA condensation agent. In this way we were ble to obtain plasmid polyplexes with a 100% yield without NA or protein contamination, after two ATPS extractions from lkaline lysates. In the first one a PEG 600—ammonium sulhate system, already described, was used and in the second one t was employed a PEG 3350—Dextran 110 system containing PEI. The isolation of polyplexes was carried out by ultrafiltraion. Although a substantial removal of Dextran and PEG was chieved the yield in polyplexes was very low (5–10%). This as due to binding of the polyplexes to the polyethersulphone embrane used. Further studies are being carried to optimize he ultrafiltration step. These results open the possibility of simultaneously purifyng and condensing the plasmid with the delivery vehicle for herapeutic applications and achieving the integration of two mportant steps on pharmaceutical plasmids production.

Determination of iron sucrose (Venofer) or iron dextran (DexFerrum) removal by hemodialysis: an in-vitro study.

BackgroundIntravenous iron is typically administered during the hemodialysis (HD) procedure. HD patients may be prescribed high-flux (HF) or high-efficiency (HE) dialysis membranes. The extent of iron sucrose and iron dextran removal by HD using HF or HE membranes and by ultrafiltration rate (UFR) is unknown.MethodsTwo in vitro HD systems were designed and constructed to determine the dialyzabiltiy of iron from a simulated blood system (SBS) containing 100 mg iron sucrose or iron dextran (system A) or 1000 mg iron sucrose (system B). Both in vitro systems utilized a 6-L closed-loop SBS system that was subject to 4 different HD conditions conducted over 4 hours: HE membrane + 0 ml/hr UFR; HE membrane + 500 ml/hr UFR; HF membrane + 0 ml/hr UFR; HF membrane + 500 ml/hr UFR. Blood flow and dialysate flow rates were 500 ml/min and 800 ml/min, respectively. The dialysate compartment was a 192-L open system for system A and a 6-L closed-loop system for system B. Samples from the SBS and dialysate compartments were taken at various time points and iron elimination rate and HD clearance was determined. Iron removal from the SBS > 15% was considered clinically significant.ResultsThe greatest percentage removal from the SBS was 13.5% and -0.03% utilizing system A and B, respectively. Iron sucrose and iron dextran dialysate concentration was below the lower limits of assay (< 2 ppm) for system A. Dialysate recovery of iron was negligible: 0 – 5.4 mg system A and 5.47 – 23.59 mg for system B. Dialyzer type or UFR did not affect iron removal.ConclusionHF or HE dialysis membranes do not remove clinically significant amounts of iron sucrose or dextran formulations over a 4-hour HD session. This effect remained constant even controlling for UFR up to 500 ml/hour. Therefore, iron sucrose and iron dextran are not dialyzed by HE or HF dialysis membranes irrespective of UFR.

Use of the disappearance rate for the estimation of lymphatic absorption during CAPD.

Several studies are discussed which investigated the usefulness of the disappearance rate of macromolecules from the peritoneal cavity for estimating convective fluid loss from the peritoneal cavity into the peritoneal lymphatic system. It is shown that dextrans are removed from the peritoneal cavity by a size-independent process at a mean rate of 1.37 +/- 0.15 ml/min, whereas the clearance from blood to dialysate of dextrans is size-dependent. The fluid removal rate estimated by the difference in bidirectional transport of inulin (1.79 +/- 0.38 ml/min; p < 0.0005) was of the same order of magnitude as has been found using the removal rate of macromolecules from the peritoneal cavity. Also, the role of local accumulation of macromolecules was studied during continuous administration of dextrans. No differences were found in the dextran disappearance rate before and after saturation of the peritoneal interstitium with dextran (1.1 +/- 0.6 vs. 1.0 +/- 0.4 ml/min). During a study using a hypoosmotic solution we calculated a net transcapillary backfiltration of fluid, whereas the dextran removal rate was in the same order of magnitude as found using commercially available dialysate. In our opinion, the disappearance rate of macromolecules is an estimate of convective fluid loss from the peritoneal cavity into the peritoneal lymphatic system.

Force-velocity relation and rate of ATP hydrolysis in osmotically compressed skinned smooth muscle of the guinea pig.

Chemically skinned guinea pig taenia coli fibre bundles showed a concentration-dependent decrease in width when incubated in media containing Dextran T500 (0-0.2 g ml-1). The maximal reduction in width, observed at 0.2 g ml-1 dextran, was 32%. The effect was reversible upon removal of dextran. Isometric force was slightly increased (about 10%) at the lowest dextran concentration (0.025 g ml-1) but decreased at higher concentrations (40% decrease at 0.2 g/ml-1). The energetic tension cost (ATP turnover/force) was decreased by about 40% after dextran addition. Force development and relaxation were markedly slower in 0.1 g ml-1 and absent in 0.2 g ml-1 dextran. In isotonic quick-release experiments 0.025 g ml-1 dextran did not influence maximal shortening velocity (Vmax) and relative stiffness, whereas 0.1 g ml-1 markedly increased stiffness and decreased Vmax to about 27%. Vanadate induced relaxation in the activated muscle (pCa 4.5) both in the absence and presence (0.1 g ml-1) of dextran and increased the rate of relaxation (pCa 9) at 0.1 g ml-1 dextran. The isometric rate of crossbridge turnover, as reflected by the energetic tension cost and the rate of relaxation, was decreased at all degrees of osmotic compression. Crossbridge turnover rate during shortening (Vmax) was unaffected at an osmotic compression of 12% (width) but was decreased at higher compression (32%).