Modified Fenton reaction for trichlorophenol dechlorination by enzymatically generated H2O2 and gluconic acid chelate

Glucose oxidase is a well-known enzyme that catalyzes the oxidation of β-d-glucose to produce gluconic acid and hydrogen peroxide. Fenton reaction is a powerful oxidation technology used for the oxidation of groundwater pollutants. For the application of Fenton reaction in groundwater remediation, successful operation of Fenton reaction near neutral pH, and on-site generation of both H₂O₂ and chelate will be beneficial. The focus of this experimental study was to couple the glucose oxidation reaction with chelate-based Fenton reaction. The idea was to use the hydrogen peroxide and chelate gluconic acid generated during glucose oxidation for the dechlorination of 2,4,6-trichlorophenol (TCP) by Fenton reaction. The oxidation of glucose was achieved using the enzyme in free and immobilized forms. The rate of production of hydrogen peroxide was determined for each system, and was used to estimate the time required for complete consumption of glucose during the process, thus avoiding any traces of glucose in the Fenton reaction. In the case of free enzyme reaction, separation of the enzyme was achieved using an ultrafiltration membrane before initiating the Fenton reaction. The oxidation of TCP by Fenton reaction was performed at varying ratios of gluconic acid/Fe, and its effect on the decomposition of TCP and H₂O₂ was studied. TCP degradation was studied both in terms of parent compound degradation and free chloride generation.     

Hydrogen Sulfide Gas Treatment by a Chemical‐Biological Process: Chemical Absorption and Biological Oxidation Steps

In order to remove high concentrations of hydrogen sulfide (H₂S) gas from anaerobic wastewater treatments in livestock farming, a novel process was evaluated for H₂S gas abatement involving the combination of chemical absorption and biological oxidation processes. In this study, the extensive experiments evaluating the removal efficiency, capacity, and removal characteristics of H₂S gas by the chemical absorption reactor were conducted in a continuous operation. In addition, the effects of initial Fe^2 + concentrations, pH, and glucose concentrations on Fe^2 + oxidation by Thiobacillus ferrooxidans CP9 were also examined. The results showed that the chemical process exhibited high removal efficiencies with H₂S concentrations up to 300 ppm, and nearly no acclimation time was required. The limitation of mass‐transfer was verified as the rate‐determining step in the chemical reaction through model validation. The Fe^2 + production rate was clearly affected by the inlet gas concentration as well as flow rate and a prediction equation of ferrous production was established. The optimal operating conditions for the biological oxidation process were below pH 2.3 and 35°C in which more than 90% Fe^3 + formation ratio was achieved. Interestingly, the optimal glucose concentration in the medium was 0.1%, which favored Fe^2 + oxidation and the growth of T. ferrooxidans CP9.     

Simulated and experimental evaluation of factors affecting the rate and extent of reductive dehalogenation of chloroethenes with glucose

Carbohydrates such as molasses are being added to aquifers to serve as electron donors for reductive dehalogenation of chloroethenes. Glucose, as a model carbohydrate, was studied to better understand the processes involved and to evaluate the effectiveness for dehalogenation of different approaches for carbohydrate addition. A simulation model was developed and calibrated with experimental data for the reductive dehalogenation of tetrachloroethene to ethene via cis-1,2-dichloroethene. The model included fermentors that convert the primary donor (glucose) into butyrate, acetate and hydrogen, methanogens, and two separate dehalogenator groups. The dehalogenation groups use the hydrogen intermediate as an electron donor and the different haloethenes as electron acceptors through competitive inhibition. Model simulations suggest first that the initial relative population size of dehalogenators and H(2)-utilizing methanogens greatly affects the degree of dehalogenation achieved. Second, the growth and decay of biomass from soluble carbohydrate plays a significant role in reductive dehalogenation. Finally, the carbohydrate delivery strategies used (periodic versus batch addition and the time interval between periodic addition) greatly affect the degree of dehalogenation that can be obtained with a given amount of added carbohydrate.     

快速检测痕量铜的光电型传感器的研制

利用铜对葡萄糖氧化酶的抑制作用,以及葡萄糖氧化酶-辣根过氧化物酶-葡萄糖(Glu)-邻联甲苯胺(OT)偶联反应体系生成蓝色底物的原理,将Glu与OT固定化制成试纸条,插入自制的便携式单色光反射计,组装出检测铜的光电型传感器。当铜的质量浓度范围为1 mg/L～100 mg/L时,光反射强度值与铜的质量浓度呈良好的线性关系。在优化的试验条件下,该方法的检测限为0.064 mg/L,检测时间为5 min。     

Effects of glucose dehydrogenase gene knock-out in Acetobacter sp. On the metabolism of carbon sources and the synthesis of 3-hydroxypropionic acid北大核心CSCD

3-Hydroxypropionic acid (3-HP) is an emerging platform chemical with a high added-value. Resting cells of Acetobacter sp. can efficiently catalyze 1,3-propanediol (1,3-PDO) to 3-HP. Glucose is oxidized by the membrane-bound dehydrogenase, resulting in an acidic environment that inhibits cell growth and reduces the biomass. We deleted the gdh gene for glucose dehydrogenase (GDH), and investigated the effects on cell growth, carbon metabolism, and 3-HP production. The gdh gene knocked-out showed a 1.72-fold increase in biomass in the mixed medium containing glucose and glycerol. A carbon flux analysis showed that glucose was converted to gluconic acid by GDH, followed by an oxidation to 2-ketogluconic acid. In addition, a small percentage of the gluconic acid was degraded via the pentose phosphate pathway. Glycerol was phosphorylated and entered the central pathway (gluconeogenesis). Results indicate that the deletion of gdh can effectively promote higher cell densities and improve the catalytic performance for the production of 3-HP, and thus provide a theoretical reference for improving the carbon source utilization and the catalytic performance of acetic acid bacteria. © 2018 Science Press. All rights reserved.     

Reaction mechanism and pathway for the hydrothermal electrolysis of organic compounds

In this study, hydrothermal electrolysis experiments using glucose (a biorelated substance) as a starting material were carried out using a specially designed autoclave at 250°C. We could understand the fundamental reaction behavior of glucose under these conditions through various kinds of experiments and product analyses. Another series of experiments using pressurized CO₂ as an electrolyte was conducted to discover whether it is possible to use CO₂ as an alternative electrolyte to the conventional KCl electrolyte, with a view to lowering the environmental impact of the process. It was found that pressurized CO₂ was useful as an environmentally friendly electrolyte, although there were still some problems in terms of the reaction efficiency.     

Effect of methyl tert-butyl ether on adipogenesis and glucose metabolism in vitro and in vivo

Methyl tert-butyl ether(MTBE), as a widely used gasoline additive, is suspected of being environmentally toxic. MTBE accumulates mainly in adipose tissue, but its effect on obesity or obesity-related metabolic disorders has not been well understood yet. Therefore, we examined the effect of MTBE on the adipose function and the related metabolic processes with both 3T3-L1 cell line and C57 BL/6 J mice model. We found that exposure to MTBE at the environmental relevant concentration(100 μmol/L) could significantly induce differentiation of preadipocyte and disturb insulin-stimulated glucose uptake of mature adipocyte.The in vivo observation in male mice showed a positive correlation of visceral white adipose tissue(vWAT) expansion and cell size increase with MTBE treatment in 14 weeks. Glucose tolerance and insulin sensitivity tests demonstrated that MTBE at 1000 μg/(kg·day)disturbed the systemic glucose metabolism in a gender-specific manner, which might be partly attributed to the alterations of gut microbiota community at genus level with respect to Akkermansia, Clostridium XlVb, and Megamonas. In summary, our study characterized the effect of MTBE on adipose tissue function and glucose homeostasis in vitro and in vivo, and revealed that systemic disorders of the glucose metabolism might be modulated by the related gut microbiota.     

不同有机碳源对小球藻的生长与产油量的影响

该研究探讨了葡萄糖和乙酸钠两种碳源对小球藻（Chlorella protothecoides）的生长与产油量的影响,并对小球藻在两种碳源混合培养下的生长与产油情况进行了分析.研究结果表明,葡萄糖和乙酸钠的浓度对小球藻的生物量和产油量都有较大的影响,最优的浓度分别为15 g/L和20.5 g/L.相对于以葡萄糖为碳源的小球藻,以乙酸钠为碳源的小球藻的生物量与含油量均较低.在混合培养条件下,葡萄糖最先被小球藻吸收利用.图5,表1,参8.     

First trimester monitoring of a pregnancy at risk for glucose phosphate isomerase deficiency

First trimester prenatal diagnosis was offered to the mother of a child affected by severe haemolytic anaemia due to glucose phosphate isomerase (GPI) deficiency. The mutant enzyme was characterized by an increased thermal lability. Both parents had 50 per cent normal red cell GPI activity. We have shown that the homozygous and heterozygous genotypes can be clearly distinguished from each other and controls by combinations of the measurement of enzyme activity and enzyme thermal lability. Examination of trophoblast cells obtained at 9 weeks of gestation led to the diagnosis of a GPI heterozygous fetus. The result was confirmed by analysis on uncultured and cultured amniotic fluid cells sampled at 16 weeks and by red blood cell studies of the healthy newborn. Prenatal diagnosis of GPI deficiency is indicated in families with previous cases resulting in severe haemolysis and mainly with the conservative view of arranging appropriate therapeutic measures for affected fetuses.