Search

β-Conglycinin, composed of three subunits (α', α and β), is the main allergen of soy protein which can cause severe allergic reactions, such as diarrhea, decreased growth performance and even death. Among them, the β subunit is more stable and difficult to remove, being one of the main nutritional inhibitors, which can be used to evaluate the concentration of β-conglycinin. However, there is no effective, accurate method for its β subunit rapid detection. Herein, we have successfully selected a high affinity β subunit aptamer (Kd = 6.9 nM) and developed a highly sensitive aptasensor. The aptasensor displayed high specificity and the β subunit at a concentration of 70-350 nM could be detected with a detection limit of 4.48 nM (3S/N). In addition, the recoveries of β subunit were more than 90%, demonstrating its practical properties for complicated conditions such as food quality control and disease diagnosis, without requiring expensive and sophisticated equipment.

As a potentially toxic heavy metal, Cadmium (Cd) can cause endoplasmic reticulum and oxidative stress, and thus lead to cell death. To explore the mechanisms of Cd toxicity, we investigated the UPRE-lacZ expression, the intracellular reactive oxygen species (ROS) and cell death in the 151 Cd-sensitive mutants of Saccharomyces cerevisiae in response to Cd stress. We identified 101 genes regulating UPRE-lacZ expression were involved in preventing ROS production and/or cell death from increasing to high levels, while mutants for 72 genes caused both elevated ROS production and cell death, indicating the Cd-induced ROS production and cell death are mediated by UPR. Genes involved in cell wall integrity (CWI) pathway, vacuolar protein sorting (VPS) and vacuolar transport, calcium/calcineurin pathway and PHO pathways were all required for the Cd-induced UPR, intracellular ROS and cell death. To conclude, this study highlights the importance of Cd-induced UPR, intracellular ROS levels and cell death that may play crucial roles in Cd-induced toxicity.

The glyoxylate shunt is a branch of the tricarboxylic acid (TCA) cycle which directly determines the synthesis of glycolate, and the balance between the glyoxylate shunt and TCA cycle is very important for the growth of Escherichia coli. In order to accumulate glycolate at high yield and titer, strategies for over-expressing glycolate pathway enzymes including isocitrate lyase (AceA), isocitrate dehydrogenase kinase/phosphatase (AceK) and glyoxylate reductase (YcdW) were analyzed. The genes encoding these three enzymes were transcribed under the control of promoter pTrc on pTrc99A, to form pJNU-3, which was harbored by strain Mgly1, resulting in strain Mgly13. Strain Mgly13 produced glycolate with 0.385 g/g-glucose yield (45.2% of the theoretical yield). Citrate synthase (GltA) converted excess acetyl-CoA and oxaloacetate to citrate and was over-expressed by pJNU-4 (pCDFDuet-1 backbone). Thus, the resulting strain Mgly134 produced glycolate with a 0.504 g/g-glucose yield (59.3% of the theoretical yield). We then eliminated the pathways involved in the degradation of glycolate, resulting in strain Mgly434, which produced glycolate with 92.9% of the theoretical yield. Following optimization of fermentation, the maximum glycolate titer from strain Mgly434 was 65.5 g/L.

Ru-catalyzed directed o-C–H arylation reactions of 2-phenylpyridine, N-phenylpyrazole, acetophenone N-(p-methoxyphenyl)imine, and 2-phenyloxazoline proceed in good to excellent yields with a number of functionalized aryl and heteroaryl bromides in neat Bu4NOAc at 120 °C. The acetate ion acts as the base and the relatively low melting point Bu4N salts (a mixture of acetate and bromide) behave as an ionic liquid. Arylation reactions of 2-phenyloxazoline proceed with concomitant oxazolidine cleavage to give 2-(N-acetylamino)ethyl benzoates promoted by side product CH3COOH. The dual-purpose ionic liquid medium is compatible with both ligandless Ru for di-arylation (optimal pre-catalyst: RuCl3·xH2O) and Ru-phosphane (optimal pre-catalyst: [RuCl2(p-cymene)]2/P(p-Tol)3 1:4) catalysts (1–5 mol-%) for selective mono-arylation.

A novel approach that involved the grafting of diblock copolymer with two types of monomer onto substrate by sequential surface initiated-atom transfer radical polymerization was proposed to prepare a mixed-mode chromatographic stationary phase. The distinguishing feature of this method is that it can be applied in the preparation of various mixed-mode stationary phases. In this study, a new reverse-phase/ion-exchange stationary phase was prepared by grafting hydrophobic styrene and cationic sodium 4-styrenesulfonate by the proposed approach onto silica surface. The chromatographic properties of the prepared stationary phase were evaluated by the separation of benzene derivatives, anilines, and β-agonists, and by the effect of pH values and acetonitrile content on the retention. Compared with typical RP columns, the prepared stationary phase achieved the better resolution and higher selectivity at a shorter separation time and lower organic content. Moreover, the application of the prepared column was proved by separating widely distributed polar and charged compounds simultaneously.

The antimicrobial activity of lactic acid bacteria is closely related to its metabolites. Our results showed that Lactobacillus plantarum DY‐6 had the highest antibacterial activities among the seven bacteria tested in this study. To fully understand the active antimicrobial substances in L. plantarum DY‐6, the cell‐free supernatant (CFS) were analyzed. Our data indicated that the antibacterial effect of the CFS was positively correlated with the growth of the bacteria, and the main antibacterial substances were lactic acid, acetic acid, propionic acid, caprylic acid, and decyl acid. Finally, this study demonstrated that the antibacterial active substance produced by the lactic acid bacteria could destroy the cell membrane structure of the bacteria, causing bacteria to fail to grow and reproduce normally, thereby exerting a bacteriostatic action. Taken together, our current findings would provide an effective method for rapid screening of antimicrobial substances.

Background Glycolate is an important α-hydroxy carboxylic acid widely used in industrial and consumer applications. The production of glycolate from glucose in Escherichia coli is generally carried out by glycolysis and glyoxylate shunt pathways, followed by reduction to glycolate. Glycolate accumulation was significantly affected by nitrogen sources and isocitrate dehydrogenase (ICDH), which influenced carbon flux distribution between the tricarboxylic acid (TCA) cycle and the glyoxylate shunt, however, the mechanism was unclear. Results Herein, we used RNA-Seq to explore the effects of nitrogen sources and ICDH knockout on glycolate production. The Mgly534 strain and the Mgly624 strain (with the ICDH deletion in Mgly534), displaying different phenotypes on organic nitrogen sources, were also adopted for the exploration. Though the growth of Mgly534 was improved on organic nitrogen sources, glycolate production decreased and acetate accumulated, while Mgly624 achieved a balance between cell growth and glycolate production, reaching 0.81 g glycolate/OD (2.6-fold higher than Mgly534). To further study Mgly624, the significant changed genes related to N-regulation, oxidative stress response and iron transport were analyzed. Glutamate and serine were found to increase the biomass and productivity respectively. Meanwhile, overexpressing the arginine transport gene argT accelerated the cell growth rate and increased the biomass. Further, the presence of Fe2+ also speeded up the cells growth and compensated for the lack of reducing equivalents. Conclusion Our studies identified that ICDH knockout strain was more suitable for glycolate production. RNA-Seq provided a better understanding of the ICDH knockout on cellular physiology and glycolate production. Electronic supplementary material The online version of this article (10.1186/s13036-019-0159-2) contains supplementary material, which is available to authorized users.

Adipic acid has been widely used for producing thermoplastic polyurethane resins, nylon 6-6, adhesives, synthetic lubricants and plasticizers, and the global market for adipic acid is estimated at approximate $6.3 billion per year. Currently, 2.85 million tons of adipic acid are produced from petrochemical sources, mostly by oxidation of KA oil (cyclohexanol and cyclohexanone) catalyzed by nitric acid. The chemical synthesis of adipic acid is of serious consequences such as greenhouse gases and heavy pollution to the environment, etc. The researchers are struggling to establish more reliable, renewable and affordable adipic acid synthesis methods, and among which, biological synthesis of adipic acid is attracting the most attention. There are two biological routes for adipate synthesis: (1) biological accumulations of precursors of adipic acid such as d -glucaric acid and cis,cis -muconic acid, which can be further catalyzed to adipate; (2) synthesis of adipate directly from carbon source. With the emergence of metabolic engineering and synthetic biology, biological synthesis of adipic acid from renewable substrates is now feasible. Here, we review the new approaches and technologies to produce adipic acid biologically, with the direct synthesis of adipic acid from the renewable substrates of special interest.

Glycolic acid is the smallest member of the α-hydroxy acid family. In order to produce glycolate from glucose via the glyoxylate shunt stably, one malate synthase gene aceB in Escherichia coli BW25113 was deleted by homologous recombination; another malate synthase gene glcB was then replaced by a DNA cassette WAK harboring isocitrate lyase gene (aceA), glyoxylate reductase gene (ycdW) and isocitrate dehydrogenase kinase/phosphatase gene (aceK). The above three genes were over-expressed in the chromosome of E. coli EYX-1WAK. This strain was then transferred 20 times on M9 medium to have a mutant strain: EYX-2 with a significantly improved growth rate. The glycolate yields of EYX-2 in the shaken flasks and the 5-L bioreactor using batch fermentation strategy under 2 vvm aeration and 800 rpm stirring speed were 0.33 g/g-glucose and 0.48 g/g-glucose, respectively. The fed-batch fermentation of EYX-2 on 120 g/L glucose had the highest titer of 56.44 g/L with 0.52 g/g-glucose yield in 120 h, and this is the highest reported glycolate yield ever.

A novel "one-pot" approach was developed for ultrarapid preparation of various hybrid monolithic columns in UV-transparent fused-silica capillaries via photoinitiated thiol-acrylate polymerization of an acrylopropyl polyhedral oligomertic silsesquioxane (acryl-POSS) and a monothiol monomer (1-octadecanethiol or sodium 3-mercapto-1-propanesulfonate) within 5 min, in which the acrylate not only homopolymerizes, but also couples with the thiol. This unique combination of two types of free-radical reaction mechanisms offers a simple way to fabricate various acrylate-based hybrid monoliths. The physical characterization, including scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and thermal gravimetric analysis was performed. The results indicated that the monothiol monomers were successfully incorporated into acryl-POSS-based hybrid monoliths. The column efficiencies for alkylbenzenes on the C18-functionalized hybrid monolithic column reached to 60 000-73 500 plates/m at the velocity of 0.33 mm/s in capillary liquid chromatography, which was far higher than that of previously reported POSS-based columns prepared via thermal-initiated free-radical polymerization without adding any thiol monomers. By plotting the plate height (H) of the alkylbenzenes versus the linear velocity (u) of the mobile phase, the results revealed a retention-independent efficient performance of small molecules in the isocratic elution. These results indicated that more homogeneous hybrid monoliths formed via photoinitiated thiol-acrylate polymerization; particularly, the use of the multifunctional cross-linker possibly prevented the generation of gel-like micropores, reducing mass transfer resistance (C-term). Another sulfonate-containing hybrid monolithic column also exhibited hydrophobicity and ion-exchange mechanism, and the dynamic binding capacity was calculated as 71.1 ng/cm (75 μm i.d.).

This study was to investigate the vitamin levels in the serum of children in the Northeast of China and some factors associated with the vitamin levels. The sera were obtained from 2096 normal children aged 1 month to 12 years in the Northeast of China. Vitamins A and E were detected using their sera by HPLC, and the level of vitamin D was detected by LC-MS. The 20 overweight children were chosen from the 7-8 age range and took additional vitamins studies for extra 3 months. The data were analyzed by IBM SPSS Statistics 21. The average levels of vitamins A, D, and E in sera samples from the 2096 children were 0.2715mg/L (95%CI, 0.2715-0.2791mg/L), 26.2848μg/L (95%CI, 25.7900-26.7786μg/L), and 8.6137mg/L (95% CI, 8.5077-8.7198mg/L), respectively. The percentages of vitamins A, D, and E deficiency were 19.61%, 47.47%, and 0.62%, respectively. For 20 children from the VDD or VAD groups, after giving them more VA and VD for 3 months, the levels of VA and VD in the sera were increased significantly; however, the average BMI has barely changed. According to our finding, vitamin D deficiency was severe, vitamin A deficiency was common, and vitamin E was insufficient in the sera of children in the Northeast of China. The levels of vitamins A, D, and E were correlated with age and overweight.

Techniques for fabricating solution-processed zinc oxide (ZnO)-based thin-film transistors (TFTs) are feasible with solution using various routes. Here, ZnO TFTs were fabricated via sol-gel method using zinc acetate as the starting reagent with different modifiers and solvents. The ZnO thin-film semiconductors with well-controlled, preferential crystal orientation and densely packed ZnO crystals can be prepared with the optimized fabrication conditions, exhibiting excellent field-effect far exceeding those of hydrogenated amorphous silicon (a-Si:H). However, the field-effect characteristics of ZnO TFTs were different for different precursor systems which were constituted by zinc acetate, modifiers and solvents. The co-modification of acetoin and monoethanolamine for the precursor system exhibited higher extent of crystal orientation and field-effect. The maximum mobility of 7.65 cm2V-1s-1 and current on-to-off ratio of ~105 - 106 have been obtained.

Tea protein has received much attention due to its potential health functions. This article studied the molecular weight, foaming capacity, foam stability, emulsifying capacity, emulsion stability, and oil absorption of tea protein prepared from tea residue by alkali extraction. The results showed that tea protein contained two components with different molecular weights (1.26 × 106 ± 1.3 × 104 and 2.4 × 104 ± 1.1 × 103). The content of the lower molecular component in tea protein was higher than the higher molecular one. When the concentration of tea protein was 4 mg/mL, its sparkling ability was satisfied, while the foaming capacity and foam stability was the best, respectively, at the conditions of pH 9 and 7. The emulsifying capacity was 62 ± 2% as well as 99 ± 1% of emulsion stability, and oil absorption was 170 ± 7%.

A novel electrochemical approach for detection of saccharides via indicator displacement assay was presented. In this system, 2-fluorophenylboronic acid and dopamine (DA) were performed as probe set. The electrochemical properties of DA and the binding to 2-fluorophenylboronic acid in phosphate buffer at different pH values were investigated by cyclic voltammetry. After addition of fructose to the solution, a competition for the binding 2-fluorophenylboronic acid occurred that led to the release of the DA. The regenerate oxidation current of DA increased with increasing fructose concentration. Under optimized experimental conditions, the peak current was linearly related to fructose concentration in the range of 0.3–5.0 mmol/L with a detection limit of 0.1 mmol/L. In addition, the interaction between 2-fluorophenylboronic acid and other cis-diol compounds such as glucose, galactose and mannose was investigated.

Thermobifida fusca is a thermophilic actinobacterium. T. fusca muC obtained by adaptive evolution preferred yeast extract to ammonium sulfate for accumulating malic acid and ammonium sulfate for cell growth. We did transcriptome analysis of T. fusca muC on Avicel and cellobiose with addition of ammonium sulfate or yeast extract, respectively by RNAseq. The transcriptional results indicate that ammonium sulfate induced the transcriptions of the genes related to carbohydrate metabolisms significantly more than yeast extract. Importantly, Tfu_2487, encoding histidine-containing protein (HPr), didn’t transcribe on yeast extract at all, while it transcribed highly on ammonium sulfate. In order to understand the impact of HPr on malate production and cell growth of the muC strain, we deleted Tfu_2487 to get a mutant strain: muCΔ2487, which had 1.33 mole/mole-glucose equivalent malate yield, much higher than that on yeast extract. We then developed an E. coli-T. fusca shuttle plasmid for over-expressing HPr in muCΔ2487, a strain without HPr background, forming the muCΔ2487S strain. The muCΔ2487S strain had a much lower malate yield but faster cell growth than the muC strain. The results of both mutant strains confirmed that HPr was the key regulatory protein for T. fusca’s metabolisms on nitrogen sources.

A one-step procedure to hydrophilize monodisperse poly (chloromethyl-styrene-co-divinylbenzene) beads has been presented with 2-hydroxy-3-[4-(hydroxymethyl)-1 H -1,2,3-triazol-1-yl] propyl 2-methylacrylate (HTMA) as monomer by surface-initiated atom transfer radical polymerization (SI-ATRP). The length of the grafted poly (HTMA) chain was varied via controlling the ratio of HTMA to initiator on the surface of the beads. Using these grafted beads as the stationary phase in hydrophilic interaction chromatography, good separation was obtained for nucleosides in the mobile phase of acetonitrile-water. It was also found that the retention time and selectivity of solutes showed a positive relationship with the length of the grafted poly (HTMA) chain.

δ-Gluconolactone was covalently coupled to aminopropyl derivatized capillary, which created hydrophilic brushes on the inner wall of the capillary. The coated capillary was shown to generate a stable electroosmotic flow (EOF) in the investigated pH range of 2.0–9.0 and to suppress effectively the adsorption of proteins. And it enabled separation of some biopolymer mixtures including basic proteins, DNA and tryptic digested bovine serum albumin (BSA) within 15 min with efficiencies up to 450,000 plates/m. The intra- and inter-day reproducibility of the coating referring to the retention times of proteins were satisfactory with mean relative standard deviations (R.S.D.) of 0.8 and 1.7%, respectively.

Butyric acid, a 4-carbon short chain fatty acid, is widely used in chemical, food, and pharmaceutical industries. The low activity of butyryl-CoA: acetate CoA-transferase in Thermobifida fusca muS, a thermophilic actinobacterium whose optimal temperature was 55°C, was found to hinder the accumulation of high yield of butyric acid. In order to solve this problem, an exogenous butyryl-CoA: acetate CoA-transferase gene (actA) from Thermoanaerobacterium thermosaccharolyticum DSM571 was integrated into the chromosome of T. fusca muS by replacing celR gene, forming T. fusca muS-1. We demonstrated that on 5g/L cellulose, the yield of butyric acid by the engineered muS-1 strain was increased by 42.9 % compared to the muS strain. On 100g/L of cellulose, the muS-1 strain could consume 90.5% of total cellulose in 144h, with 33.2g/L butyric acid produced. Furthermore, on the mix substrates including the major components of biomass: cellulose, xylose, mannose and galactose, 70.4g/L butyric acid was produced in 168h by fed-batch fermentation. To validate the ability of fermenting biomass, the muS-1 strain was grown on the milled corn stover ranging from 200 to 250μm. The muS-1 strain had the highest butyrate titer 17.1g/L on 90g/L corn stover.

Malic acid is mainly used as an acidulant and taste enhancer in the beverage and food industry. Previously, a mutant strain Thermobifida fusca muC, obtained by adaptive evolution was found to accumulate malic acid on cellulose with low yield. In this study, the malic acid synthesis pathway in T. fusca muC was confirmed to be from phosphoenolpyruvate to oxaloacetate, followed by reduction of oxaloacetate to malate. To increase the yield of malic acid by the muC strain significantly, the carbon flux from pyruvate was redirected to oxaloacetate by expressing an exogenous pyruvate carboxylase (PCx) gene from Corynebacterium glutamicum ATCC 13032 in the chromosome of T. fusca muC-16. The yield of malic acid in the engineered strain muC-16 was increased by 47.9% compared to the parent strain muC. The muC-16 strain was then grown on ∼100 g/L cellulose and the highest titer of malic acid was 62.76 g/L by batch fermentation. T. fusca muC-16 strain converted milled corn stover to malic acid with the highest titer of 21.47 g/L with minimal treatment.

Mast cells and basophils are multifunctional effector cells that contain abundant secretory granules in their cytoplasm. Both cell types are involved in a variety of inflammatory and immune events, producing an array of inflammatory mediators, such as cytokines. The aim of the study was to examine whether isoquercitrin modulates allergic and inflammatory reactions in the human basophilic KU812 cells and to elucidate its influence on the phosphorylation of mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB activation. The KU812 cells were stimulated with phorbol-12-myristate 13-acetate plus the calcium ionophore A23187 (PMACI). The inhibitory effects of isoquercitrin on the productions of histamine and pro-inflammatory cytokines in the stimulated KU812 cells were measured using cytokine-specific enzyme-linked immunosorbent (ELISA) assays. Western blotting analysis was used to assess the effects of isoquercitrin on the MAPKs and NF-κB protein levels. Our results indicated that the isoquercitrin treatment of PMACI-stimulated KU812 cells significantly reduced the production of histamine and the pro-inflammatory cytokines, such as interleukin (IL)-6, IL-8, IL-1β, and tumor necrosis factor (TNF)-α. The treated cells exhibited decreased phosphorylation of extracellular signal-regulated kinase (ERK), revealing the role of ERK MAPK in isoquercitrin-mediated allergy inhibition. Furthermore, isoquercitrin suppressed the PMACI-mediated activation of NF-κB in the human basophil cells. In conclusion, the results from the present study provide insights into the potential therapeutic use of isoquercitrin for the treatment of inflammatory and allergic reactions.

Anaerobic treatability of foul condensate discharged from the evaporation-enrichment process of black liquor from a paper and pulp mill was investigated by using batch and a small scale UASB reactors. The foul condensate used in the experiment was anaerobically biodegraded and the removal rate of CODCr in anaerobic treatment was expressed as the first-order reaction with respect to the biodegradable CODCr, and the reaction rate constant was 3-5 X 10-5l·mg-1·h-1. The CODCr removal efficiency in an UASB reactor was as high as 70% when the volumetric CODCr loading was lower than 10kg·m3·d-1. Methane productivity of the condensate was 0.16-0.24 Nm3·kg-1-CODCr.

Background Bevacizumab has been suggested as a new treatment modality for cerebral radiation necrosis due to its ability to block the effects of vascular endothelial growth factor (VEGF) in leakage-prone capillaries, though its use still remains controversial in clinical practice. Methods The use of bevacizumab in 17 patients with symptomatic cerebral radiation necrosis poorly controlled with dexamethasone steroid treatments was examined between March 2010 and January 2012. Bevacizumab therapy was administered for a minimum of two cycles (7.5 mg/kg, at two-week interval) with a median of four bevacizumab injections. Changes in bi-dimensional measurements of the largest radiation necrosis lesions were observed by gadolinium-enhanced and T2-weighted magnetic resonance imaging (MRI). Additionally, dexamethasone dosage, Karnofsky performance status (KPS), adverse event occurrence and associated clinical outcomes were recorded for each patient. Results MRI analysis revealed that the average reduction was 54.9% and 48.4% in post-gadolinium and T2-weighted sequence analysis, respectively. Significant clinical neurological improvements were expressed in 10 patients according to KPS values. Dexamethasone reduction was achieved four weeks after initiation of bevacizumab in all patients, with four patients successfully discontinuing dexamethasone treatment. Mild to moderate bevacizumab-related adverse events, such as fatigue, proteinuria and hypertension were observed in three patients. Upon follow-up at 4 to 12 months, 10 patients showed clinical improvement, and 7 patient deaths occurred from tumor progression (5 patients), recurrent necrosis (1 patient), and uncontrolled necrosis-induced edema (1 patient). Conclusions These findings suggest bevacizumab as a promising treatment for cerebral radiation necrosis induced by common radiation therapies, including external beam radiotherapy (EBRT), stereotactic radiosurgery (SRS), and fractionated stereotactic radiotherapy (FSRT).