Coexistence Of Glucose Research Articles

Chemical Characteristics of Dark-Brown Humic-like Substances Formed from the Abiotic Condensation of Maillard Precursors with Different Glycine Concentrations

The Maillard reaction is a type of nonenzymic browning process, and it is also an abiotic humification process of sugars, amino acids and phenols catalyzed by δ-MnO2. It is considered to be one of the possible pathways for the formation of humic-like substances (HLS). The change in the ratio of the Maillard precursors inevitably affects the chemical characteristics of HLS, among which the effect of amino acids concentration on the humification pathway and HLS formation has not yet been reported. In view of this, the glucose, glycine and catechol were chosen as tested objects for the present study, and the method of liquid shake-flask culture was adopted. Both catechol and glucose with fixed concentrations were added into a phosphate buffer solution (pH 8.0) containing δ-MnO2, and only the glycine concentration was adjusted in the sterile culture system. The supernatant solution and dark-brown residue were collected dynamically within 360 h through the centrifugation method. The E4/E6 ratio and total organic C (TOC) of the supernatant solution, the C content of the humic-like acid (CHLA), CHLA/CFLA (C content of fulvic-like acid) ratio and FTIR spectra of the dark-brown residue and the E4/E6 ratio and atomic ratio of humic-like acid (HLA) extracted from the dark-brown residue were systematically analyzed to reveal the effect of different glycine concentrations on the abiotic humification pathways and the characteristics of related products from the Maillard reaction under abiotic processes. The results showed that (1) Under the influence of the addition of different glycine concentrations, the structure of organic molecules in the supernatant after culture tended to be simplified, and the addition of three lower concentrations (0, 0.03 and 0.06 mol/L) of glycine made the E4/E6 ratios increase by 100.4%, 57.7% and 33.0%, respectively, and obtained a simpler structure of organic molecules in the supernatant than that of 0.12 and 0.24 mol/L glycine, which made the E4/E6 ratios increase by 5.6% and 18.0%, merely. After culture, the TOC content in the supernatant solution of each treatment decreased to varying degrees, and the addition of Maillard precursors effectively inhibited the loss of TOC in the supernatant solution, especially the addition of glycine at a concentration of 0.06 mol/L, which only reduced the TOC content by 0.1%. (2) The greater the concentration of glycine added, the higher proportion of aromatic C structure existed in the dark-brown residue. O-containing functional groups from the dark-brown residue and δ-MnO2 were bound to each other through hydrogen bonding, and (3) During the culture process, the CHLA treated with the addition of Maillard precursors was significantly higher than that of the CK control. Compared with the result at 0 h, the addition of higher concentrations of glycine (0.12 and 0.24 mol/L) were more conducive to the formation of HLA, making the CHLA increase by 666.2% and 422.7%, which were much more than these results for 256.6%, 282.2% and 360.0% from three concentrations of glycine (0, 0.03 and 0.06 mol/L) at the end of culture. After culture, the structure of HLA molecules treated by the addition of Maillard precursors became more complex, and the overall performance showed that the higher the concentration of added glycine, the more complex the HLA molecules became. Under the coexistence of glucose and catechol, the addition of glycine could promote abiotic condensation and improve the condensation degree of HLA molecules, among which the addition of 0.12 mol/L glycine had the most significant effect. Compared with the CK control, the addition of Maillard precursors could achieve a higher increase in the CHLA/CFLA ratio, which was more beneficial to the improvement of humus quality.

Revealing carbon-iron interaction characteristics in sludge-derived hydrochars under different hydrothermal conditions

Hydrothermal conversion is seen as a potential sustainable solution for the disposal and utilization of sewage sludge. One-step hydrothermal carbonization was used to prepare iron-based sludge hydrochars, and the microstructure properties of hydrochars under different hydrothermal conditions were investigated, with emphasis on the inherent interaction mechanisms between carbon and iron. The aromaticity of hydrochars increased with increasing hydrothermal temperature and time, whereas the specific surface area and pore volume as well as magnetic characteristics of hydrochars were only contingent on temperature. Once the temperature reached 160 °C, Fe2O3 in sludge was completely transformed into Fe3O4 in hydrochars. Simulated experiments suggest that glucose is more advantageous than protein in the iron transformation and mesopore formation. The coexistence of glucose, protein, and FeCl3 improved the aromaticity as well as specific surface area and pore volume of hydrochars. This study provides a basis for designing high performance iron-based sludge hydrochars.

Resveratrol production of a recombinant Scheffersomyces stipitis strain from molasses

Resveratrol is a plant-derived aromatic compound with beneficial properties and it is required to develop a resveratrol production process from inexpensive biomass feedstocks. Here, we investigated the potential of Scheffersomyces stipitis, a non-conventional yeast with the capacity to utilize a wide range of sugars, to produce resveratrol from molasses, which is a by-product of sugar refineries. The S. stipitis strain metabolically engineered for resveratrol production produced resveratrol from 60 g/L mixed sugar (sucrose, glucose, and fructose), while its resveratrol titer decreased as the proportions of glucose and fructose increased. Sucrose consumption of the S. stipitis strain was clearly suppressed by the coexistence of glucose, fructose, and even ethanol. Quantitative analysis of intracellular metabolites involved in resveratrol biosynthesis using capillary electrophoresis time-of-flight mass spectrometry revealed that the composition of these sugars has a significant effect on the intracellular accumulation of glycolytic metabolites and AMP, which is an important factor involved in some cellular metabolic responses. Furthermore, the S. stipitis strain produced 1076 ± 167 mg/L of resveratrol in the fermentation with commercial sugarcane molasses (120 g/L of total sugars) as the substrate. To our knowledge, this is the first report on carbon catabolite repression in S. stipitis caused by the coexistence of sucrose, glucose, and fructose and resveratrol production from molasses. These results indicate great potential of the cost-effective resveratrol production process from molasses substrates using recombinant S. stipitis.

A bio-inspired highly selective enzymatic glucose sensor using a red blood cell membrane.

In the development of enzymatic glucose sensors, accurate glucose sensing has been a challenging task because of the existence of numerous interfering molecules in the blood. Meanwhile, red blood cells (RBCs) selectively uptake glucose via a membrane protein called glucose transporter-1. In this study, we developed the RBC membrane (RBCM)-coated enzymatic glucose sensors that mimic the glucose uptake. The RBCM-coated sensors were examined via scanning electron microscopy, atomic force microscopy, and ATR-FTIR. We optimized the glucose permeability of the RBCM filter by controlling the thickness of the filter. The sensing range of the optimized sensor was 1-15 mM, the detection limit was 0.66 mM, and the sensitivity was 2.978 μA mM-1. Intriguingly, the RBCM-coated sensor was highly accurate and precise, despite the coexistence of glucose and interfering molecules (e.g., mannose, galactose, ascorbic acid, uric acid, and cysteine). For each interfering molecule, the errors of our sensor were 0.8 to 2.3%, which was 4.8-14.2 times more accurate than the uncoated one. A similar result was verified for a human serum sample containing countless interfering molecules. Also, the sensing performance of the sensor was consistent after 4 weeks of storage. The results suggest that applying RBCM may improve the selectivity of various types of glucose sensors including the continuous monitoring system.

STUDY ON THE SYNTHESIS OF MESOPOROUS CERIA IN THE PRESENCE OF GLUCOSE AND ACRYLAMIDE

Mesoporous ceria with high specific surface area have been prepared using eerie ammonium nitrate and non-surfactants organic compounds glucose, acrylamide via hydrothermal method. The influence of the main synthesis variables have been studied, including cerium ion valence, composition of raw materials, hydrothermal temperature and time. XRD, TEM, TG and nitrogen adsorption techniques have been used to characterize the samples. Results indicate that cerium ion valence has the most important effect on surface area of mesoporous ceria. Cerium ion valence changing from +3 to +4 causes higher surface area of samples. Moreover the coexistence of glucose and acrylamide in the synthesis is essential to obtain samples with high surface areas, whereas surface areas of samples are lower in the absence of glucose or acrylamide. TEM shows that the mesoporous ceria are composed of three-dimensional disordered primary nanoparticles. The average size of primary particles and mesopores are both a few nanometers.

Effect of biodegradable substrates on the removal rate of concentrated p-phenol sulphonic acid in the solid phase aerobic biological treatment process

The effects of the co-existence of biodegradable substrates such as glucose and peptone on removal rate of concentrated refractory organic pollutants in a solid phase aerobic biological treatment process were investigated. The DOC removal rate with co-existence of glucose and peptone became constant around 4–6 kg-C/m 3 per day at the steady state. But, the DOC removal rate decreased from 5.0 to 3.5 kg-C/m 3 per day when p-phenol sulphonic acid (PSA) was fed as the sole organic substrate. This suggests that the co-existence of glucose and peptone accelerated the removal of PSA in the bioreactor. In addition, from the analytical results of microbial quinines a, remarkable change in the quinone profiles was observed along with increasing PSA loading. The dominant quinone in the solid phase bioreactor treating the mixture of GP wastewater and PSA were UQ-8 and menaquinone (MK)-6, and those treating the wastewater containing only PSA as a sole carbon source was MK-6 followed by MK-7 and UQ-8, suggesting that different microbes contributed to PSA degradation with the change of experimental conditions.

Effects of citric acid on cell growth and schizophyllan formation in the submerged culture of Schizophyllum commune

Cell growth and schizophyllan formation of Schizophyllum commune were greatly influenced by the citric acid. Effects of citric acid on schizophyllan batch culture were investigated in the batch cultures by citric acid supplemented initially from 0 to 5 g/L. The cell growth rate was decreased from 0.85 to 0.36 day-1, the product yield was enhanced from 0.097 to 0.173 g/g, and specific product yield was enhanced from 0.21 to 0.39 g/g as the citric acid increased from 0.0 to 5.0 g/L. These results indicated that cell growth was inhibited but schizophyllan formation was stimulated by the citric acid. The product formation kinetics was mixed-type kinetics, and the behavior of product formation was likely to be growth-associated as the concentration of citric acid increased. An improved two-stage SPG with co-supplement of glucose and citric acid was proposed and validated in this study. As a result, higher product yield 0.6 g/g was obtained in the second stage of the process , and higher productivity 0.66 g/L hr was obtained. These results suggest that the co-existence of glucose and citric acid in the medium is essential for SPG synthesis.

Effects of biodegradable substrates and microbial concentration on the acclimation of microbes to acrylonitrile in aerobic submerged biofilter

The effects of coexistence-of biodegradable substrates and microbial concentration on the acclimation of microbes to acrylonitrile (AN) in an aerobic submerged biofilter were investigated on the basis of kinetic and ecological studies. The experimental results show that the acclimation of microbial film to AN was promoted by a higher microbial concentration in the biofilter and by the coexistence of glucose and peptone in the influent. It was clarified that the upper limit of AN loading to the biofilter for the ultimate degradation, i.e., complete mineralization, of the influent AN was about 2.0-2.2 kg/m3. d. In addition, a new microbial quinone profile method was applied for the analysis of the microbial community change in the biofilter. The change in quinone profiles of the microbial film during the acclimation to AN suggested that Brevibacterium sp., Pseudomonas aeruginosa and Corynebacterium sp. could contribute to the degradation of AN in the aerobic biofilter.

Analysis of microbial acclimation to refractory chemicals in wastewater using respiratory quinone profiles

The effects of initial microbial concentration and the coexistence of biodegradable substrates on the acclimation of microbes to acrylonitrile (AN) was investigated in an aerobic submerged biofilter using respiratory quinone profiles. The acclimation of microbes to AN was accelerated by increased initial microbial concentrations in the biofilter and by the coexistence of glucose and peptone in the influent. The change in quinone profiles of microbial films during the course of acclimation suggested that Brevibacterium sp., Pseudomonas aeruginosa and Corynebacterium sp. contributed to the degradation of AN in the aerobic biofilter.

Analysis of microbial acclimation to refractory chemicals in wastewater using respiratory quinone profiles

The effects of initial microbial concentration and the coexistence of biodegradable substrates on the acclimation of microbes to acrylonitrile (AN) was investigated in an aerobic submerged biofilter using respiratory quinone profiles. The acclimation of microbes to AN was accelerated by increased initial microbial concentrations in the biofilter and by the coexistence of glucose and peptone in the influent. The change m quinone profiles of microbial films during the course of acclimation suggested that Brevibacterium sp., Pseiulomonas aeruginosa and Corynebacterium sp. contributed to the degradation of AN in the aerobic biofilter.

Effects of biodegradable substrates and microbial concentration on the acclimation of microbes to acrylonitrile in aerobic submerged biofilter

The effects of coexistence-of biodegradable substrates and microbial concentration on the acclimation of microbes to acrylonitrile (AN) in an aerobic submerged biofilter were investigated on the basis of kinetic and ecological studies. The experimental results show that the acclimation of microbial film to AN was promoted by a higher microbial concentration in the biofilter and by the coexistence of glucose and peptone in the influent. It was clarified that the upper limit of AN loading to the biofilter for the ultimate degradation, i.e., complete mineralization, of the influent AN was about 2.0–2.2 kg/m3. d. In addition, a new microbial quinone profile method was applied for the analysis of the microbial community change in the biofilter. The change in quinone profiles of the microbial film during the acclimation to AN suggested that Brevibacterium sp., Pseudomonas aeruginosa and Corynebacterium sp. could contribute to the degradation of AN in the aerobic biofilter.

Studies of microbial acclimation to hard chemicals on the basis of respiratory quinone profiles and kinetic analyses

The population dynamics of microbes in the biological wastewater treatment processes such as a submerged biofilter was investigated to obtain basic information to determine the optimal operating conditions. The effects of coexistence of biodegradable substances such as glucose and peptone on the acclimation of microbes in the biofilm to hard chemicals such as acrylonitrile (AN), which is poorly biodegradable and a volatile substance, was investigated on the basis of the respiratory quinone profile. Kinetic study of the removal of AN in the course of acclimation of microbes was investigated using a laboratory-scale submerged biofilter as well. It was ascertained that the acclimation of the microbes to AN was accelerated by coexistence of biodegradable substances, and the microbial phase after acclimation differed from those with the coexistence of glucose and peptone. The quinone profiles in the acclimation showed that Brevibacterium sp. and Pseudomonas aeruginosa, of which the predominant quinone of the respiratory chain is menaquinone-8(H2) and ubiquinone-9, respectively, multiplied selectively in the acclimation course without and with the coexistence of glucose and peptone, respectively. It was also made clear that there were few kinds and number of protozoa and metazoa in the biofilter treating the wastewater containing AN.

Studies of microbial acclimation to hard chemicals on the basis of respiratory quinone profiles and kinetic analyses

The population dynamics of microbes in the biological wastewater treatment processes such as a submerged biofilter was investigated to obtain basic information to determine the optimal operating conditions. The effects of coexistence of biodegradable substances such as glucose and peptone on the acclimation of microbes in the biofilm to hard chemicals such as acrylonitrile (AN), which is poorly biodegradable and a volatile substance, was investigated on the basis of the respiratory quinone profile. Kinetic study of the removal of AN in the course of acclimation of microbes was investigated using a laboratory-scale submerged biofilter as well. It was ascertained that the acclimation of the microbes to AN was accelerated by coexistence of biodegradable substances, and the microbial phase after acclimation differed from those with the coexistence of glucose and peptone. The quinone profiles in the acclimation showed that Brevibacterium sp. and Pseudomonas aeruginosa, of which the predominant quinone of the respiratory chain is menaquinone-8(H2) and ubiquinone-9, respectively, multiplied selectively in the acclimation course without and with the coexistence of glucose and peptone, respectively. It was also made clear that there were few kinds and number of protozoa and metazoa in the biofilter treating the wastewater containing AN.

Galactose Tolerance Test Using a Bioassay of Galactose

Fukutome and his collaborators1)2) reported that the growth of mutabiles of E.coli was inhibited by galactose and that this phenomenon could be used as a bioassay of galactose. We intended to study the availability of such kind of bioassay for galactose tolerance test in liver function tests. If the inhibitory effect of galactose is not influenced by the coexistence of glucose, we can measure the blood level of galactose without the differentiating analysis of that from glucose (fermentation procedure). Although glucose of a concentration higher than some level reduced very much the inhibitory effect of galactose on the growth of mutabiles, we could find the conditions where the influence of glucose could be neglected and the measurement of galactose could be performed without any fermentation procedure.