Impact Of Glucose Concentration Research Articles

Evaluation of Cr(VI) Reducing Capability of Bacillus licheniformis DAS1 Using a Multifactor Experimental Approach

The current study is about detoxifying soil and water contaminated with toxic Cr(VI). To ensure that DAS1 could develop as well as possible, the pH was changed between 4 and 10. DAS1 showed its highest growth at pH 8, and at the same pH, it had an 85% potential to remediate by converting Cr(VI) to Cr(III). Immobilized bacteria increased the reduction of Cr(VI) to Cr(III) from the culture medium to 90.4%. The impact of glucose concentrations between 0.5 and 2.5 g.L-1 was examined. The greatest development was seen at pH 8 and 2 g.L-1 glucose concentration. The remediation potential was improved by up to 96% when the growing medium contained 200 mg.L-1 Cr(VI). The value of ks (0.434 g.L-1) demonstrated the substrate’s affinity for bacteria in accordance with the Monod equation, while μ max (0.090 h) demonstrated that DAS1 required 11.11 h for maximal growth. The multifactor experimental design was used to analyze mixed cultures of DAS1 and DAS2 in a 1:1 ratio, and it was determined that the X3Y2Z1 experiment design was best for completely removing Cr(VI) from the growing medium. By making pores using Na2EDTA, it was determined that the cell membrane’s impermeability did not cause Cr(VI) resistance in DAS1. The delayed lag phase indicated that the enzyme activity was inductive rather than constitutive.

Microwell Array Based Opto-Electrochemical Detections Revealing Co-Adaptation of Rheological Properties and Oxygen Metabolism in Budding Yeast.

Microdevices composed of microwell arrays integrating nanoelectrodes (OptoElecWell) are developed to achieve dual high-resolution optical and electrochemical detections on single Saccharomyces cerevisiae yeast cells. Each array consists of 1.6×105 microwells measuring 8µm in diameter and 5µm height, with a platinum nanoring electrode for in situ electrochemistry, all integrated on a transparent thin wafer for further high-resolution live-cell imaging. After optimizing the filling rate, 32% of cells are effectively trapped within microwells. This allows to analyse S. cerevisiae metabolism associated with basal respiration while simultaneously measuring optically other cellular parameters. In this study, the impact of glucose concentration on respiration and intracellular rheology is focused. It is found that while the oxygen uptake rate decreases with increasing glucose concentration, diffusion of tracer nanoparticles increases. The OptoElecWell-based respiration methodology provides similar results compared to the commercial gold-standard Seahorse XF analyzer, while using 20 times fewer biological samples, paving the way to achieve single cell metabolomics. In addition, it facilitates an optical route to monitor the contents within single cells. The proposed device, in combination with the dual detection analysis, opens up new avenues for measuring cellular metabolism, and relating it to cellular physiological indicators at single cell level.

Overexpression, overproduction, purification, and characterization of rhGH in Escherichia coli

Overexpression of insoluble human growth hormone (hGH) in cytoplasm was achieved by E. coli Rosetta-gami B(DE3) [pET21a (+)-hGH]). For overexpression of hGH, effects of eight factors including temperature, type and concentration of carbon source, IPTG and MgSO4 , buffering capacity, induction time, yeast extract/peptone ratio on rhGH production were studied by Plackett-Burman screening. Maximum production of rhGH was 0.681 g/L, and results of statistical analysis showed that induction temperature and glucose have the greatest effect and the presence of MgSO4 increases rhGH expression and reduces biomass concentration. So, the effect of ethanol and MgSO4 concentrations on the rhGH production was examined according to the central composite experimental design. The ANOVA of the results showed rhGH production increases to 1.128 g/L in 4 g/L MgSO4 and 1% ethanol. Then, the impact of glucose concentration and induction time on the rhGH production was evaluated in two levels in the fermenter by Taguchi statistical method. Under optimum conditions, OD600nm 4 and 10 g/L glucose crude rhGH concentration 4.17 g/L was obtained, which is one of the highest value ever reported. Finally, rhGH was purified using the biophysical and biochemical techniques comprising circular dichroism, fluorescent spectroscopy, and dynamic light scattering, and it was confirmed that the produced protein is comparable to the commercial standard sample.

Impact of glucose concentration on productivity and yield of hydrogen production by the new isolate Clostridium beijerinckii Br21

AbstractThis paper presents a detailed analysis of the batch kinetic fermentative assays data used to evaluate how glucose concentration influences fermentative H2 production, including the non‐dissociated acid concentration threshold, with the new isolate Clostridium beijerinckii Br21. Fermentative batch assays for hydrogen (H2) production were conducted with initial glucose concentrations of 5.2, 27.2, 54.4, 97.2, or 154.4 mmol/L without pH control. The dry cell mass (X), glucose (S), and product (H2) concentrations and the pH were monitored for 60 h. Increasing initial glucose concentration raised the maximum specific H2 production rate to values as high as 1.19 mmol H2/mg X · h. However, the H2 production yield (YH2/S) decreased from 2.23 to 0.2 mmol H2/mmol glucose. The initial glucose concentration that provided the best compromise between YH2/S and H2 productivity was 37 mmol/L (6.7 g/L). The lactic acid, acetic acid, and butyric acid concentrations enhanced at higher initial glucose concentrations, leading to the largest pH decrease. Lower pH favoured non‐dissociated acids, which switched the Clostridium metabolism to solventogenesis. The threshold acid concentrations for C. beijerinckii Br21 solventogenesis were non‐dissociated butyric acid at 8 mmol/L and total non‐dissociated acetic and butyric acids at 13 mmol/L. Glucose supply and pH control in continuous or fed‐batch biorreactors could culminate in higher H2 productivity and yield by C. beijerinckii Br21.

Impact of Glucose Concentration and NaCl Osmotic Stress on Yeast Cell Wall β-d-Glucan Formation during Anaerobic Fermentation Process

Yeast β-glucan polysaccharide is a proven immunostimulant molecule for human and animal health. In recent years, interest in β-glucan industrial production has been increasing. The yeast cell wall is modified during the fermentation process for biomass production. The impact of environmental conditions on cell wall remodelling has not been extensively investigated. The aim of this research work was to study the impact of glucose and NaCl stress on β-glucan formation in the yeast cell wall during alcoholic fermentation and the assessment of the optimum fermentation phase at which the highest β-glucan yield is obtained. VIN 13 Saccharomyces cerevisiae (S. cerevisiae) strain was pre-cultured for 24 h with 0% and 6% NaCl and inoculated in a medium consisting of 200, 300, or 400 g/L glucose. During fermentation, 50 mL of fermented medium were taken periodically for the determination of Optical Density (OD), cell count, cell viability, cell dry weight, β-glucan concentration and β-glucan yield. Next, dry yeast cell biomass was treated with lytic enzyme and sonication. At the early stationary phase, the highest β-glucan concentration and yield was observed for non-NaCl pre-cultured cells grown in a medium containing 200 g/L glucose; these cells, when treated with enzyme and sonication, appeared to be the most resistant. Stationary is the optimum phase for cell harvesting for β-glucan isolation. NaCl and glucose stress impact negatively on β-glucan formation during alcoholic fermentation. The results of this work could comprise a model study for yeast β-glucan production on an industrial scale and offer new perspectives on yeast physiology for the development of antifungal drugs.

Glucose Serum Concentrations and Cardiovascular Disease in Patients on the End Stage of Renal Disease without Diabetes Mellitus.

Background/Aim: It is still controversial whether tighter glycemic control is associated with better clinical outcomes in patients with kidney failure. We examined the association between glucose serum concentrations and cardiovascular disease in patients on the end stage of renal disease without diabetes mellitus. Methods: We studied 76 patients on on-line hemodiafiltration. Cardiovascular disease was defined by the existence of coronary disease (CD). Arterial stiffness was measured as carotid-femoral pulse wave velocity (c-fPWV) and carotid augmentation index (AIx). The concentrations of beta2-microglobulin (β2M) and insulin were measured by radioimmunoassays and insulin resistance by HOMA-IR. We built a logistic-regression analysis to examine the role of glucose on cardiovascular disease after adjustment for the traditional and specific risk factors for dialysis patients. Results: Serum glucose was positively correlated with beta2M, insulin and HOMA-IR (r = 0.361, p = 0.002, r = 0.581, p = 0.001 and r = 0.753, p = 0.001 respectively). Logistic-regression analysis did not show significant impact of glucose concentrations on cardiovascular disease after adjustment for traditional and specific risk factors. Conclusions: The association between elevated glucose serum concentrations and represented by coronary syndrome cardiovascular disease in patients on the end stage of renal disease without diabetes mellitus was not found significant.

High glucose impairs ATP formation on the surface of human peripheral blood B lymphocytes

Diabetes-associated lymphocyte dysfunction may be attributed to the direct effect of hyperglycemia, but the impact of glucose concentration on B cell functionality is not fully resolved. Since, adenosine 5′-triphosphate (ATP) and its metabolite adenosine are the core constituents of the purinergic signaling network involved in regulation of immune response we aimed to investigate the impact of high glucose concentration on ATP outflow and metabolism on B cell surface. Purified human peripheral blood B cells cultured at high glucose (25mM) concentration released significantly less ATP (~60%) comparing to cells cultured in low glucose (5mM) concentration. We observed that high glucose altered ATP hydrolysis on B cell surface due to increased activity of nucleoside triphosphate diphosphohydrolase-1 (NTPDase-1/CD39). In the presence of 10μM [3H]AMP and 100μM ATP significant quantities of [3H]ADP and [3H]ATP were generated, although the AMP to ADP phosphorylation potential of B cells cultured in high glucose decreased significantly. The flow cytometry analysis revealed that the level of ecto-adenylate kinase 1β (AK1β) on surface of B cells cultured in high glucose decreased significantly. Inhibition of NTPDase1/CD39 activity with 100μM ARL67156 resulted in decreased cell viability, although significantly more viable cells retained in the culture media containing low glucose compared to high glucose media. Selective inhibition of P2X7 purinergic receptor irrespective of glucose concentration completely protected B cells against the ARL 67156-induced cell death. We assume that high glucose-induced alteration of ATP handling on B cell surface might contribute to impaired functionality of B cells in diabetes.

Impact of glucose concentration on cardiac ventricular repolarization under I Kr/I Ks blocking agents

Drug-induced QT interval prolongation is a condition likely to be aggravated by diabetes. The objective of this study was to evaluate how glucose concentration may modulate drug effects on ventricular repolarization and on cardiac repolarizing potassium currents. Guinea pig hearts were Langendorff-retroperfused and monophasic action potential duration (MAPD) was measured. Glucose (1, 5 or 20 mmol/L) was tested with either dofetilide (a specific I Kr blocker), chromanol 293B (a specific I Ks blocker) or both. Effects of glucose (1, 5 or 20 mmol/L) on I Kr blockade mediated by dofetilide were also measured in HERG-transfected HEK293 cells in the absence vs presence of the P-glycoprotein drug transporter, using the whole cell patch-clamp technique. Our results suggest that both hypo- and hyperglycemia potentiate the MAPD-prolonging and I Kr-blocking properties of dofetilide. P-glycoprotein drug extrusion efficacy appears as a key determinant of dofetilide's I Kr-blocking effect. This efficacy appears to be affected by glucose concentration, particularly hyperglycemia.