Abstract  A simple one pot hydrothermal procedure for the synthesis of cobalt selenide (CoSe) decorated reduced graphene oxide (rGO) is reported along with the application of this hybrid material as a new electrocatalyst for glucose oxidation. In alkaline media, glassy carbon electrodes modified with CoSe-rGO composite dispersed in chitosan display excellent reproducibility for the determination of glucose along with a high sensitivity of 480 mu A mM(-1) cm(-2), a linear dynamic range of up to 10 mM, a lower limit of detection of 2.5 mu M and an exceptionally high maximum current density of 5.41 +/- 0.03 mA cm(-2). Bulk electrolysis measurements carried out with the CoSe-rGO/chitosan modified glassy carbon plate revealed that the oxidation of glucose can proceed beyond the formation of gluconolactone with formate detected by H-1-NMR and CO2 detected by gas chromatography; the latter result showing the ability to achieve complete oxidation of glucose. Studies with ascorbic and uric acid showed that their interference with respect to glucose measurement either is negligible or can be overcome.

Abstract  BACKGROUNDLeaching kinetics of the roasted (at 600 degrees C) chromite overburden of Sukinda mines Orissa, India, was studied with optimized data generated through response surface methodology (RSM) coupled with Box-Behnken design (BBD). The effects of oxalic, citric and gluconic acid concentration (50-150 mmol L-1), reaction temperature (60 degrees to 80 degrees C) and period (up to 3 h) on metal (nickel and cobalt) dissolution were examined.

RESULTSExtraction of nickel and cobalt to the extent of 63.61% and 44.33%, respectively, was achieved using 150 mmol L-1 oxalic acid at 80 degrees C in 3 h; compared with other acids, oxalic acid leached more of the metals. Associated apparent activation energy for Ni was 74 kJ mol(-1), and that for cobalt was 84.37 kJ mol(-1) during the first hour, and 80.99 kJ mol(-1) for the remaining period since cobalt leaching followed biphasic kinetics.

CONCLUSIONDissolution of nickel and cobalt from the roasted chromite overburden was highly dependent on the amenability of ore minerals to organic acid attack. Nickel leaching data fit the three-dimensional diffusion mechanism of the type Ginstling Brounsthein (GB) equation while a mixed kinetic model consisting of spherical geometry and the GB equation was followed for cobalt. This work presents maximum recovery of nickel and cobalt from chromite overburden using organic acid reported to date. (c) 2013 Society of Chemical Industry

Abstract  Aerobic oxidation of glucose in the presence of Au/Al2O3 catalysts with different dispersion of supported gold and Au/C catalysts containing highly dispersed gold nanoparticles was studied at varied glucose:Au molar ratios. The studies were focused on determining the contribution of the mass-transfer processes to the overall reaction kinetics in different regimes. The Au/Al2O3 catalysts were more active than the Au/C catalysts at high glucose:Au molar ratios. Among the alumina-supported catalysts with different metal dispersion, the highest TOF at high glucose:Au molar ratios was characteristic of the Au/Al2O3 catalysts bearing metal particles of 1-5 nm in size. Under these conditions, the high effectiveness factor of the Au/Al2O3 catalysts (>95%) was observed at a uniform gold distribution through the support granules. For the Au/C catalysts with the non-uniform distribution of gold nanoparticles through the catalyst grains, the apparent reaction rate was affected by internal diffusion (the effectiveness factor of a catalyst grain is ca. 70%), while the interface gas liquid solid oxygen transfer influenced the overall reaction kinetics as well. At a low glucose:Au molar ratio the reaction rate was limited by oxygen dissolution in the aqueous phase. In this mass transfer regime the rate of glucose oxidation over the carbon-supported catalysts exceeds the reaction rate over the alumina-supported catalyst, which is attributed to a higher adhesion of the hydrophobic carbon support to the gas liquid interface facilitating the oxygen mass transfer towards catalytic sites. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  A novel glucose biosensor was developed based on a 4-amino thiophenol/Au nanoparticle/glucose oxidase (GOD)-horseradish peroxidase (HRP)/6-mercapto-1-hexanol-11-mercaptoundecanoic acid/Au electrode. The modified electrode could be used to detect glucose based on the polymerization of aniline induced by HRP and H2O2 which was produced by the reduction of O-2 accompanied by the oxidation of glucose into gluconic acid via GOD. With the increase of glucose, more H2O2 molecules were produced and then a growing number of polyaniline (PANI) molecules were formed on the modified electrode surface, which resulted in the decrease of peak current of Fe(CN)(6)(3-/4-) because the formed PANI hindered the electron transfer of Fe(CN) 6(3-/4-) toward the electrode surface. Based on the decrease of peak current of Fe(CN)(6)(3-/4-), the glucose concentration could be determined accurately and selectively. The resulted biosensor exhibited a wide linear range from 16.5 mM to 10.0 mM, a high sensitivity of 41.78 mu A mM(-1) cm(-2) and good selectivity. The glucose biosensor exhibits some advantages over the traditional GOD electrodes in terms of a close to zero applied potential. Moreover, the used electrode might be used as a H2O2 sensor due to its good electrocatalytic response for H2O2.

Abstract  Glucose is a key energy supplier and nutrient for tumor growth. Herein, inspired by the glucose oxidase (GOx)-assisted conversion of glucose into gluconic acid and toxic H2 O2 , a novel treatment paradigm of starving-like therapy is developed for significant tumor-killing effects, more effective than conventional starving therapy by only cutting off the energy supply. Furthermore, the generated acidic H2 O2 can oxidize l-Arginine (l-Arg) into NO for enhanced gas therapy. By using hollow mesoporous organosilica nanoparticle (HMON) as a biocompatible/biodegradable nanocarrier for the co-delivery of GOx and l-Arg, a novel glucose-responsive nanomedicine (l-Arg-HMON-GOx) has been for the first time constructed for synergistic cancer starving-like/gas therapy without the need of external excitation, which yields a remarkable H2 O2 -NO cooperative anticancer effect with minimal adverse effect.

Abstract  Epimerization of a non-anomeric stereogenic center in carbohydrates is an important transformation in the synthesis of natural products. In this study an epimerization procedure of the allylic alcohols of glycals by cyclopentadienylruthenium catalyst 1 is presented. The epimerization of 4,6-O-benzylidene-D-glucal 4 in toluene is rapid, and an equlibrium with its D-allal epimer 5 is established within 5 min at room temperature. Exchange rates for allal and glucal formation were determined by 1D (1) H EXSY NMR experiments to be 0.055 s(-1) and 0.075 s(-1) , respectively. For 4-O-benzyl-L-rhamnal 8 the epimerization was less rapid and four days of epimerization was required to achieve equilibration of the epimers at room temperature. The epimerization methodology was subsequently combined with acylating enzymes in a dynamic kinetic asymmetric transformation (DYKAT), giving stereoselective acylation to the desired stereoisomers 12, 13, and 15. The net effect of this process is an inversion of a stereogenic center on the glycal, and yields ranging from 71 % to 83 % of the epimer were obtained.

Abstract  Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and the leading cause of visual impairment in working-age adults. Diabetic patients often develop DR despite appropriate control of systemic risk factors, suggesting the involvement of other pathogenic factors. We hypothesize a plasma metabolic signature of DR that is distinct and resolvable from that of diabetes alone. A nested population-based case-control metabonomic study was first performed on 40 DR cases and 40 diabetic controls using gas chromatography-mass spectrometry. Eleven metabolites were found to be correlated with DR, and the majority were robust when adjusted for metabolic risk factors and confounding kidney disease. The metabolite markers 2-deoxyribonic acid; 3,4-dihydroxybutyric acid; erythritol; gluconic acid and ribose were validated in an independent sample set with 40 DR cases, 40 diabetic controls and 40 non-diabetic individuals. DR cases and diabetic controls were matched by HbA1c in the validation set. Activation of the pentose phosphate pathway was identified from the list of DR metabolite markers. The identification of novel metabolite markers for DR provides insights into potential new pathogenic pathways for this microvascular complication and holds translational value in DR risk stratification and the development of new therapeutic measures.

Abstract  We show that a perylene bisimide (PBI)-based gelator forms self-sorted mixtures with a stilbene-based gelator. To form the self-sorted gels, we use a slow pH change induced by the hydrolysis of glucono-δ-lactone (GdL) to gluconic acid. We prove that self-sorting occurs using NMR spectroscopy, UV-Vis spectroscopy, rheology, and viscometry. The corresponding xerogels are photoconductive. Importantly, the wavelength dependence of the photoconductive films is different to that of the films formed from the perylene bisimide alone. Transient absorption spectroscopy of the xerogels reveals changes in the spectrum of the PBI on the picosecond timescale in the presence of stilbene with a PBI radical anion being formed within 10 ps when the stilbene is present. The ability to form the PBI radical anion under visible light leads to the enhanced spectral response of the multicomponent gels. These systems therefore have potential as useful visible-active optoelectronics.

Abstract  The aim of this study was to observe whether Polycal has inhibitory activity on ligation-induced experimental periodontitis and related alveolar bone loss in rats following topical application to the gingival regions. One day after the ligation placements, Polycal (50, 25, and 12.5 mg/mL solutions at 200 μL/rat) was topically applied to the ligated gingival regions daily for 10 days. Changes in bodyweight, alveolar bone loss index, and total number of buccal gingival aerobic bacterial cells were monitored, and the anti-inflammatory effects were investigated via myeloperoxidase activity and levels of the pro-inflammatory cytokines IL-1β and TNF-α. The activities of inducible nitric oxide synthase (iNOS) and lipid peroxidation (MDA) were also evaluated. Bacterial proliferation, periodontitis, and alveolar bone loss induced by ligature placements were significantly inhibited after 10 days of continuous topical application of Polycal. These results indicate that topical application of Polycal has a significant inhibitory effect on periodontitis and related alveolar bone loss in rats mediated by antibacterial, anti-inflammatory, and anti-oxidative activities.

Abstract  To obtain a better understanding of responsive mechanism of plant cells in response to hydrodynamic mechanical stress, a metabolic profiling approach was used to profile metabolite changes of Taxus cuspidata cells under laminar shear stress. A total of 65 intracellular metabolites were identified and quantified, using gas chromatography coupled to time-of-flight mass spectrometry. Potential biomarkers were found by the principal component analysis as well as partial least squares combined with variable influence in the projection. Trehalose, sorbitol, ascorbate, sucrose, and gluconic acid were mainly responsible for the discrimination between shear stress induced cells and control cells. Further analysis by mapping measured metabolite concentrations onto the metabolic network revealed that shear stress imposed restrictions on primary metabolic pathways by inhibiting tricarboxylic acid cycle, glycolysis, and N metabolism. To adapt to the shear condition, cells responded by starting defensive programs. These defensive programs included coinduction of glycolysis and sucrose metabolism, accumulation of compatible solutes, and antioxidative strategy. A strategy of defense mechanisms at the level of metabolites for T. cuspidata cells when challenged with the shear stress was proposed.

Abstract  Aims: This study was designed to gain knowledge of three Controlled Denomination of Origin (DOC) Italian sweet white Passito wines (Caluso Passito DOC, Cinque Terre Sciacchetra DOC and Passito di Pantelleria DOC) produced in several areas of Italy from grapes dried with different systems and vinification techniques.

Methods and results: Physico-chemical and chromatic characteristics, sodium, potassium, gluconic acid, glucono-gamma-lactone, acetaldehyde, sorbitol, laccase, organic acids and semi-quantitative free volatile profile were determined on these wines.

Caluso Passito DOC wines presented higher contents of organic acids (above all, malic acid), main metabolites from noble Botrytis cinerea (laccase, glycerol, gluconic acid and benzaldehyde) and low contents of total polyphenols. Among the volatile components, normal fatty acid ethyl esters (ethyl hexanoate and ethyl octanoate), branched-chain esters (ethyl 2-methylpropanoate, ethyl 2-methylbutyrate, ethyl 3-methylbutyrate) and benzaldeyde characterized this Passito wine. Cinque Terre Sciacchetra DOC wines showed the lowest total acidity with a lower amount of malic acid and a higher content of polyphenols. This wine was characterized by some predominant acetates (isoamyl acetate), alcohols, benzaldehyde and an isoprenoid, B-damascenone.

Passito di Pantelleria DOC wines presented higher amounts of ashes resulting in higher pH values compared to the other two Passito typologies. Due to its production from aromatic grapes, it showed several varietal components such as terpenes, while ethyl esters/acetates and alcohols were less represented.

Conclusion: This survey provides information allowing the characterisation of three Passito dessert wines at high commercial value.

Significance and impact of the study: This study provides oenological information to be utilised to protect and valorise the Controlled Denomination of Origin sweet wine production and contributes to the preservation of traditional and terroir productions and their commercialization.

Abstract  The field-effect enzymatic detection (FEED) technique was used to control the kinetics of the enzymatic conversion of glucose to gluconolactone. The glucose-gluconolactone conversion occurring at an enzyme-immobilized electrode, a well-studied process, was confirmed using mass spectrometry. Electrochemical studies showed that the glucose oxidation current depends on the gating voltage VG and the ion concentration of the sample solution. Additionally, the depletion of glucose in the sample also showed a dependence on VG. FEED was used to detect H2O2 on the zepto-molar level in order to show the ultrasensitive detection capability of the technique. These results, while providing evidence for the proposed mechanism of FEED, indicate that VG controls the conversion process. The effect of VG on the glucose-gluconolactone conversion was demonstrated by the observed VG-dependent kinetic parameters of the conversion process.

Abstract  The glucose-free platelet-additive solution (termed AR solution), developed by Adams and Rock [Transfusion 1988;28:217-220], was modified by adding glucose as an energy substrate for platelets and maltose to prevent platelet lysis and by replacing sodium gluconate with sodium phosphate for better pH maintenance. The new platelet-additive solution (termed Seto solution) contained 90 mM NaCl, 5 mM KCl, 3 mM MgCl2, 17 mM tri-sodium citrate, 4.9 mM NaH2PO4, 20.1 mM Na2HPO4, 23 mM sodium acetate, 28.8 mM maltose, and 23.5 mM glucose with a pH of 7.4. The solution was sterilized by autoclaving in plastic bags in nitrogen to prevent glucose caramelization at high pH. Plasma-poor platelet concentrates prepared by adding Seto solution to the pelleted platelet buttons were stored in a LE-2 polyolefin bag at 22 degrees C with constant agitation for 5 days. The platelets suspended in Seto solution maintained oxygen consumption at a rate of 1.1 nmol/min/10(9) platelets after 5-day storage, with glucose consumption and lactate production rates of 0.5 +/- 0.2 and 1.2 +/- 0.2 nmol/min/10(9) platelets, respectively. This resulted in a final mean pH of 7.0. Those suspended in AR solution ceased glycolysis within 3 days because residual plasma glucose had been consumed. This was associated with decreases in percent hypotonic shock response and aggregation induced by adenosine diphosphate and collagen. Lactate dehydrogenase discharge in AR solution was 5 and 8 times higher at day 3 and day 5, respectively, than that of Seto solution. Morphologically, there were no ballooned platelets after storage in Seto solution.(ABSTRACT TRUNCATED AT 250 WORDS)

Abstract  The preterm infant fed parenterally is prone to some demineralisation due in part to insufficient Calcium (Ca) and Phosphorus (P) retention. In an attempt to augment Ca and P retention, we prepared a standardised parenteral solution containing calcium gluconate and glucose-1-phosphate (Phocytan) as source of phosphorus, yielding a daily supply of 75 mg/kg Ca and 45 mg/kg P. 28 very low birthweight infants were randomly assigned to receive either this solution (high Ca P ; n = 15) or a conventional formulation containing calcium gluconate and potassium mono- and dibasic phosphate delivering 42 mg/kg Ca and 36 mg/kg P daily (low Ca P ; n = 13). In the high Ca P daily retention was respectively 80% and 99% for Ca and P whereas in the low Ca P group, retention was 70% and 82%. Serum parathormone levels were significantly lower in the high Ca P group. We conclude that parenteral nutrition with a new high Ca P supplement results in an augmented Ca and P retention in very low birthweight infants. This may help to prevent neonatal bone demineralization.

Abstract  A novel and practical glucose biosensor was fabricated with immobilization of Glucose oxidase (GOx) enzyme on the surface of citric acid (CA) assisted cobalt ferrite (CF) magnetic nanoparticles (MNPs). This innovative sensor was constructed with glassy carbon electrode which is represented as (GOx)/CA-CF/(GCE). An explicit high negative zeta potential value (-22.4 mV at pH 7.0) was observed on the surface of CA-CF MNPs. Our sensor works on the principle of detection of H2O2 which is produced by the enzymatic oxidation of glucose to gluconic acid. This sensor has tremendous potential for application in glucose biosensing due to the higher sensitivity 2.5 microA/cm2-mM and substantial increment of the anodic peak current from 0.2 microA to 10.5 microA.

Abstract  Phosphate-solubilizing and phytate-mineralizing bacteria collectively termed as phosphobacteria provide a sustainable approach for managing P-deficiency in agricultural soils by supplying inexpensive phosphate to plants. A phosphobacterium Bacillus subtilis strain KPS-11 (Genbank accession no. KP006655) was isolated from potato (Solanum tuberosum L.) rhizosphere and characterized for potato plant growth promoting potential. The strain utilized both Ca-phosphate and Na-phytate in vitro and produced 6.48 μg mL(-1) indole-3-acetic acid in tryptophan supplemented medium. P-solubilization after 240 h was 66.4 μg mL(-1) alongwith the production of 19.3 μg mL(-1) gluconic acid and 5.3 μg mL(-1) malic acid. The extracellular phytase activity was higher (4.3 × 10(-10) kat mg(-1) protein) than the cell-associated phytase activity (1.6 × 10(-10) kat mg(-1) protein). B. subtilis strain KPS-11 utilized 40 carbon sources and showed resistance against 20 chemicals in GENIII micro-plate system demonstrating its metabolic potential. Phytase-encoding gene β-propeller (BPP) showed 92% amino acid similarity to BPP from B. subtilis (accession no.WP_014114128.1) and 83% structural similarity to BPP from B. subtilis (accession no 3AMR_A). Potato inoculation with B. subtilis strain KPS-11 increased the root/shoot length and root/shoot weight of potato as compared to non-inoculated control plants. Moreover, rifampicin-resistant derivative of KPS-11 were able to survive in the rhizosphere and on the roots of potato up to 60 days showing its colonization potential. The study indicates that B. subtilis strain KPS-11 can be a potential candidate for development of potato inoculum in P-deficient soils.

Abstract  A number of gram-negative bacteria regulate gene expression in a cell density-dependent manner by quorum sensing via N-acylhomoserine lactones (AHLs). Gluconacetobacter intermedius NCI1051, a gram-negative acetic acid bacterium, produces three different AHLs, N-decanoyl-l-homoserine lactone, N-dodecanoyl-L-homoserine lactone, and an N-dodecanoyl-L-homoserine lactone with a single unsaturated bond in its acyl chain, as determined by liquid chromatography-tandem mass spectrometry. Two genes encoding an AHL synthase and a cognate regulator were cloned from strain NCI1051 and designated ginI and ginR, respectively. Disruption of ginI or ginR abolished AHL production, indicating that NCI1051 contains a single set of quorum-sensing genes. Transcriptional analysis showed that ginI is activated by GinR, which is consistent with the finding that there is an inverted repeat whose nucleotide sequence is similar to the sequence bound by members of the LuxR family at position -45 with respect to the transcriptional start site of ginI. A single gene, designated ginA, located just downstream of ginI is transcribed by read-through from the GinR-inducible ginI promoter. A ginA mutant, as well as the ginI and ginR mutants, grew more rapidly in medium containing 2% (vol/vol) ethanol and accumulated acetic acid at a higher rate with a greater final yield than parental strain NCI1051. In addition, these mutants produced larger amounts of gluconic acid than the parental strain. These data demonstrate that the GinI/GinR quorum-sensing system in G. intermedius controls the expression of ginA, which in turn represses oxidative fermentation, including acetic acid and gluconic acid fermentation.

Abstract  Soya bean protein isolate (SPI) dispersions (7.25%, w/v) were heated at 65, 75, 85 or 90 degrees C for different time periods to produce SPI aggregates with diverse degrees of denaturation and particle size to investigate the effects on calcium sulphate (CaSO4)-induced tofu-type gel. The results revealed that gel hardness and water-holding capacity correlated positively with the degree of denaturation of glycinin (11S) and the particle size of the SPI aggregates. The formed gels showed more uniform and denser network structures with increasing degrees of denaturation and particle size of SPI. Hydrophobic interaction was speculated to be the crucial factor for the retention of gels prepared by SPI whose degree of denaturation by 11S was lower than 4.35%. However, disulphide bonds probably played a more important role in the retention of gels generated by SPI with the 11S denaturation degree of >84.47%. Moreover, the bulk density of the protein aggregates might determine the gel structures to a certain extent.

Abstract  Base-free aerobic oxidation of glucose in presence of Au/Al2O3, Au/CeO2, Au/CeO2(20 wt%)/Al2O3, Au/CeO2(25 wt%)/ZrO2 and Au/CeO2(50 wt%)/ZrO2 catalysts using molecular oxygen at atmospheric pressure is studied. Within the whole series high conversion and selectivity to gluconic acid are observed after 18 h of reaction at 120 degrees C. The activity and especially the selectivity changes are related to the support nature in a way that the higher the Lewis acidity of the support the lower the selectivity to gluconic acid and the higher the production of lactic acid. The highest yield to gluconic acid is obtained over Au/Al2O3 for which the influence of the reaction time, temperature and stirring rate are further evaluated and discussed. (C) 2016 Elsevier B.V. All rights reserved.

Abstract  Glucose provides essential function towards metabolism processes in biological systems and has close relationships with diabetes or hypoglycemia. In this work, a very simple, one-step colorimetric method based on MnO2 nanosheets for highly sensitive glucose detection is proposed. Glucose can be efficiently catalyzed by using glucose oxidase (GOx) to generate gluconic acid and hydrogen peroxide (H2O2). Consequently, the obtained H2O2 triggers the rapid decomposition of MnO2 nanosheets and generates an obvious absorbance change at 370 nm. By simply monitoring the absorbance variation, a low detection limit of 0.17 mu M for glucose was obtained with a linear range from 0.5 mM to 50 mM by visual observation and quantitative analysis. In addition, the proposed method was successfully applied to the determination of glucose in serum with satisfactory recoveries. This proposed strategy is very fast, convenient, and environmentally friendly and requires no sophisticated instruments as well as complicated functional nanomaterials, which reveals that this method has great potential for diabetes mellitus study and biosensing applications.

Abstract  Cardiomyocytes (CMs) undergo a rapid transition from hyperplastic to hypertrophic growth soon after birth, which is a major challenge to the development of engineered cardiac tissue for pediatric patients. Resting membrane potential (Vmem) has been shown to play an important role in cell differentiation and proliferation during development. We hypothesized that depolarization of neonatal CMs would stimulate or maintain CM proliferation in vitro. To test our hypothesis, we isolated postnatal day 3 neonatal rat CMs and subjected them to sustained depolarization via the addition of potassium gluconate or Ouabain to the culture medium. Cell density and CM percentage measurements demonstrated an increase in mitotic CMs along with a ~2 fold increase in CM numbers with depolarization. In addition, depolarization led to an increase in cells in G2 and S phase, indicating increased proliferation, as measured by flow cytometry. Surprisingly depolarization of Vmem with either treatment led to inhibition of proliferation in cardiac fibroblasts. This effect is abrogated when the study was carried out on postnatal day 7 neonatal CMs, which are less proliferative, indicating that the likely mechanism of depolarization is the maintenance of the proliferating CM population. In summary, our findings suggest that depolarization maintains postnatal CM proliferation and may be a novel approach to encourage growth of engineered tissue and cardiac regeneration in pediatric patients.

Abstract  Streptomyces are ubiquitous soil bacteria well known for their ability to produce a wide range of secondary metabolites including antibiotics. In their natural environments, they co-exist and interact with complex microbial communities and their natural products are assumed to play a major role in mediating these interactions. Reciprocally, their secondary metabolism can be influenced by the surrounding microbial communities. Little is known about these complex interactions and the underlying molecular mechanisms. During pairwise co-culture experiments, a fluorescent Pseudomonas, Pseudomonas fluorescens BBc6R8, was shown to prevent the production of the diffusible blue pigment antibiotic γ-actinorhodin by Streptomyces coelicolor A3(2) M145 without altering the biosynthesis of the intracellular actinorhodin. A mutant of the BBc6R8 strain defective in the production of gluconic acid from glucose and consequently unable to acidify the culture medium did not show any effect on the γ-actinorhodin biosynthesis in contrast to the wild-type strain and the mutant complemented with the wild-type allele. In addition, when glucose was substituted by mannitol in the culture medium, P. fluorescens BBc6R8 was unable to acidify the medium and to prevent the biosynthesis of the antibiotic. All together, the results show that P. fluorescens BBc6R8 impairs the biosynthesis of the lactone form of actinorhodin in S. coelicolor by acidifying the medium through the production of gluconic acid. Other fluorescent Pseudomonas and the opportunistic pathogen Pseudomonas aeruginosa PAO1 also prevented the γ-actinorhodin production in a similar way. We propose some hypotheses on the ecological significance of such interaction.

Abstract  A new glucose oxidase from Aspergillus niger was isolated and characterized. The enzyme showed different kinetic and stability characteristics when compared to a commercially available batch of A. niger glucose oxidase. The gene encoding the new glucose oxidase was isolated and DNA sequence analysis of the coding region showed 80% identity to the sequence of a glucose oxidase gene previously published. However, the similarity of the non-coding sequences up- and downstream of the open reading frame was much less, showing only 66% and 50% identity respectively. Despite the low degree of similarity between the promotor region of the new gene and the previously published one, the new glucose oxidase was likewise induced by calcium carbonate. In addition, we showed that this induction occurred on the transcriptional level. Observations concerning the effect of gluconolactone and the levels of glucose-6-phosphate isomerase upon calcium carbonate induction suggested that the enhancement of glucose oxidase biosynthesis by calcium carbonate was accompanied by a metabolic shift from glycolysis to the pentose phosphate pathway.

Abstract  During a screening for the enzyme mannitol dehydrogenase (MDH; EC 1.1.1.67), which is to be employed in the enzymatic conversion of fructose to mannitol, the bacterium Pseudomonas fluorescens, the fungus Schizophyllum commune and the yeast Torulaspora delbruckii were identified as promising producers of NAD C-dependent MDH In P. fluorescens the formation of this enzyme activity could be induced by mannitol, whereas in T. delbruckii synthesis was provoked by fructose. The enzyme was constitutively formed during growth of S. commune on easily metabolizable sugars. Mannitol dehydrogenase from P. fluorescens and T. delbruckii were purified 65-fold and 280-fold, respectively, to apparent homogeneity, while only a partially purified preparation of the enzyme from S. commune was obtained. The dehydrogenases were further characterized in consideration of a possible coenzyme-dependent process in which the reduction of fructose is coupled to the enzymatic oxidation of glucose to gluconate, thus regenerating the reduced form of the nicotinamide coenzyme. The pH-optima for the reduction fructose --> mannitol for the enzymes from P. fluorescens, S. commune and T. delbruckii were found to be 7.3, 7.2 and 6.3, respectively, whereas for the reverse oxidation mannitol --> fructose the pH-optima were 10.0, 9.8, and 10.0, respectively. MDH from S. commune was rather unstable, losing 50% of its activity within 60 h at 4 degrees C. In contrast, the other two enzymes were stable at room temperature and retained 50% of their activity after 42 h (P. fluorescens) or 166 h (T. delbruckii. Furthermore, both enzymes could be efficiently stabilized so that their half-life time exceeded well over 1500 h at ambient temperature. The enzymes of the latter organisms were found to be rather specific for both their coenzyme and their substrates. A glucose dehydrogenase CEC 1.1.1.47) from Bacillus megaterium, which is necessary for the continuous regeneration of the coenzyme and catalyzes the NAD(+)-dependent oxidation of glucose to glucono-delta-lactone, was characterized with respect to its thermal stability.

Abstract  The potential for extraction of copper from wood treated with micronised, nano or soluble forms of copper has been evaluated in view of chemical remediation. In focus were EDTA, oxalic acid, bioxalate, and D-gluconic acid for extraction of Cu from treated wood. Bioxalate extractions for 24 h resulted in Cu removal over 95% for all tested materials, and the effectiveness of oxalic acid extraction was very similar to that of nano-CuO-treated wood. Bioxalate was more effective than oxalic acid in removing Cu from ACQ-D, MCQ, MCA, CA-C and Cu-ethanolamine treated wood. D-gluconic acid extractions resulted in the lowest Cu removal for nano-CuO even though D-gluconic acid was effective for all other materials. As the pH of D-gluconic acid decreased, Cu removal was improved except for nano-CuO. There is no distinctive difference in Cu removal from wood treated with ACQ-D, MCQ, CA-C, MCA and Cu-ethanolamine.