Abstract  Sucrose from sugarcane is produced in abundance in Brazil, which provides an opportunity to manufacture other high-value products. Gluconic acid (GA) can be produced by multi-enzyme conversion of sucrose using the enzymes invertase, glucose oxidase, and catalase. In this process, one of the byproducts is fructose, which has many commercial applications. This work concerns the batch mode production of GA in an airlift reactor fed with sucrose as substrate. Evaluation was made of the influence of temperature and pH, as well as the thermal stability of the enzymes. Operational conditions of 40 °C and pH 6.0 were selected, based on the enzymatic activity profiles and the thermal stabilities. Under these conditions, the experimental data could be accurately described by kinetic models. The maximum yield of GA was achieved within 3.8 h, with total conversion of sucrose and glucose and a volumetric productivity of around 7.0 g L(-1) h(-1).

Abstract  Among the studies about conversion of renewable resources, glucose oxidation to gluconic acid received very much attention in recent years. The present paper describes kinetic and mechanistic aspects of the liquid-phase glucose oxidation. Therefore a 0.3 % Au/Al2O3 catalyst prepared by the incipient wetness method was used. The reaction conditions were varied between 20 to 60 degrees C, pH 7 to 10, catalyst concentrations between 50 to 1200 mg l(-1) and initial glucose concentrations between 10 to 1000 mmol l(-1) The concentration of dissolved oxygen was tracked for most experiments. An increasing activity was found with increasing pH value in the range between pH 7 and 10, and with increasing temperature in the range between 20 and 60 degrees C, whereas the selectivity to gluconic acid remained unchanged at > 99 % under these conditions. The activation energy was determined to be 53 kJ mol(-1). Analysis of the reaction orders with regard to glucose and oxygen leads to the conclusion that the Eley-Rideal model proposed by Beltrame et al. (2006) should be discarded for the gold-catalyzed glucose oxidation. Hydrogen peroxide is formed as by-product in glucose oxidation under oxygen atmosphere, whereas hydrogenated products are by-products under oxygen-free conditions. These observations have been explained by a modified oxidative dehydrogenation mechanism.

Abstract  Water soluble porphyrins have many perfect analytical figures of merit. A water-soluble sulfonated porphyrin (H2TEHPPS) was used to build a novel platform for sensitive assays of hydrogen peroxide and glucose based on the different effects of Fe(2+) and Fe(3+) on H2TEHPPS. H2O2 or Fe(2+) alone cannot induce a fluorescence change in H2TEHPPS, but Fe(3+) can quench the fluorescence of H2TEHPPS significantly. Interestingly, glucose is oxidized to gluconolactone by GOD and generates an equivalent hydrogen peroxide, and the produced H2O2 also oxidizes Fe(2+) to Fe(3+) and causes the fluorescence quenching of H2TEHPPS. According to this, a sensitive sensor for hydrogen peroxide and glucose has been demonstrated, which can determine H2O2 and glucose in a relative simple and sensitive way. The detection limits were 1.3 × 10(-7) M and 3.2 × 10(-7) M for H2O2 and glucose, respectively. In addition, the glucose in serum samples was determined successfully using this sensing platform. It is also noteworthy that H2O2 can be released in almost all oxidations catalyzed by oxidases, which suggests that this newly proposed H2O2 probe can be readily extended to sense other oxidases and their specific substrates.

Abstract  This study aimed to evaluate the effect of Datura stramonium on rats by examining the differences in urine and serum metabolites between Datura stramonium groups and control group. SIMCA-P+12.0.1.0 software was used for partial least-squares discriminant analysis (PLS-DA) to screen for the differential metabolites. Fifteen metabolites in urine including malonic acid, pentanedioic acid, D-xylose, D-ribose, xylulose, azelaic acid, threitol, glycine, butanoic acid, D-mannose, D-gluconic acid, galactonic acid, myo-inositol, octadecanoic acid, pseudouridine and ten metabolites in serum including alanine, butanedioic acid, L-methionine, propanedioic acid, hexadecanoic acid, D-fructose, tetradecanoic acid, D-glucose, D-galactose, oleic acid were selected as the characteristic metabolites. The PLS-DA scores plot indicated that serum and urine metabolites have a variety of changes among low dose group, high dose group and control group. These metabolites were related with amino metabolism, lipid metabolism and energy metabolism. The result reflected the relationship between metabolites in rat fluid and Datura stramonium spectra. Potential differences in metabolites and metabolic pathway analysis showed that the establishment of urine and serum metabolomics methods for further evaluating drug has great significance.

Abstract  Monolithic ruthenium catalysts (Ru/inorganic washcoat/cordierite) were evaluated for use in a monolith loop reactor process for hydrogenating glucose to sorbitol. Washcoat formulations included alumina, silica, titania, zirconia, and selected mixed oxides. Commercially attractive reaction rates were attained with several catalysts. Rates normalized to the amount of Ru were lower for monolithic catalysts than for Ru/C slurry catalyst benchmarks, most likely because of internal mass-transfer limitation. The concentrations of reaction byproducts (gluconic acid, ethylene glycol, and mannitol) were analyzed by high-performance liquid chromatography and are compared to slurry benchmarks. Selected monolithic catalysts exhibited a slow but steady activity decline in extended life testing (tens of runs); the deactivation mechanism has not yet been elucidated. With some further catalyst optimization, monolith catalysts can successfully replace the Raney nickel catalysts currently in use at the commercial scale, lower the overall catalyst cost, and reduce metal leaching into the reaction product.

Abstract  Two isomers of the [Co(tren)(D-Glc1A1,2H(-2)-(KO1,2)-O-2)](+) (1) chelate are formed in equal parts in the reaction of [Co(tren)Cl-2]Cl and sodium gluconate. In contrast, the gluconate's 2-amino-2-deoxy derivative glucosaminate formed a single isomer of [Co(tren)(D-Glc1A2N1H(-1)-(KN)-N-2, O-2)](2+) (2). Crystals of the OC-6-34 isomer of 1, [1a]PF6 center dot H2O, showed the support of the metal-binding site by intramolecular hydrogen bonds. Due to the inertness of the cobalt(III) chelates, spectroscopy on redissolved crystals of [la]PF6 center dot H2O allowed the separation of the two C-13 NMR signal sets of the isomeric mixture. In a DFT approach, a small energy difference explained the formation of two isomers in the case of the gluconate. A larger difference was obtained for the glucosaminate, in line with the known rules for the stereospecific amino acid-Co(tren) chelation.

Abstract  We herein present a three-in-one nanoplatform for sensing, self-assembly, and cascade catalysis, enabled by cyclodextrin modified gold nanoparticles (CD@AuNPs). Monodisperse AuNPs 15-20 nm in diameter are fabricated in an eco-friendly way by the proposed one-step colloidal synthesis method using CD as both reducing agents and stabilizers. First, the as-prepared AuNPs are employed as not only scaffolds but energy acceptors for turn-on fluorescent sensing based on guest replacement reaction. Then, the macrocyclic supramolecule functionalized AuNPs can be controllably assembled and form well-defined one- and two-dimensional architectures using tetrakis(4-carboxyphenyl)porphyrin as mediator. Finally, in addition to conventional host-guest interaction based properties, the CD@AuNPs possess unpredictable catalytic activity and exhibit mimicking properties of both glucose oxidase and horseradish peroxidase simultaneously. Especially, the cascade reaction (glucose is first catalytically oxidized and generates gluconic acid and H2O2; then the enzymatic H2O2 and preadded TMB (3,3',5,5'-tetramethylbenzidine) are further catalyzed into H2O and oxTMB, respectively) is well-achieved using the AuNPs as the sole catalyst. By employing a joint experimental-theoretical study, we reveal that the unique catalytic properties of the CD@AuNPs probably derive from the special topological structures of CD molecules and the resulting electron transfer effect from the AuNP surface to the appended CD molecules.

Abstract  Schizosaccharomyces was initially considered as a spoilage yeast because of the production of undesirable metabolites such as acetic acid, hydrogen sulfide, or acetaldehyde, but it currently seems to be of great value in enology.o ced Nevertheless, Schizosaccharomyces can reduce all of the malic acid in must, leading to malolactic fermentation. Malolactic fermentation is a highly complicated process in enology and leads to a higher concentration of biogenic amines, so the use of Schizosaccharomyces pombe can be an excellent tool for assuring wine safety. Schizosaccharomyces also has much more potential than only reducing the malic acid content, such as increasing the level of pyruvic acid and thus the vinylphenolic pyranoanthocyanin content. Until now, few commercial strains have been available and little research on the selection of appropriate yeast strains with such potential has been conducted. In this study, selected and wild Sc. pombe strains were used along with a Saccharomyces cerevisiae strain to ferment red grape must. The results showed significant differences in several parameters including non-volatile and volatile compounds, anthocyanins, biogenic amines and sensory parameters.

Abstract  BACKGROUND: Several diseases affect bone healing and physiology. Many drugs that are commonly used in orthopaedics as "analgesics" or anti-inflammatory agents impair bone healing. Stressful conditions are associated with decreased serum osteocalcin concentration. High endorphin levels alter calcium metabolism, blocking the membrane channels by which calcium normally enters cells. The consequent decrease of intracellular calcium impairs the activities of calcium-related enzymes. Naloxone is a pure opioid antagonist. Morphine-induced osteocalcin inhibition was abolished when osteoblasts were incubated with naloxone. Naloxone restored the altered cellular and tissue physiology by removing beta-endorphins from specific receptors. However, this is only possible if the circulating Ca concentration is adequate. The aim of the present study was to evaluate the efficacy of parenteral naloxone administration in inducing fast mineralization and callus remodelling in a group of sheep with a standardised bone lesion.

METHODS: Twenty ewes were randomly assigned to 4 treatment groups. Group A acted as control, group B received a solution of calcium gluconate, group C a solution of naloxone, and group D a solution of calcium gluconate and naloxone. A transverse hole was drilled in the left metacarpus, including both cortices, then parenteral treatment was administered intramuscularly, daily for four weeks. Healing was evaluated by weekly radiographic examination for eight weeks. For quantitative evaluation, the ratio of the radiographic bone density between the drill area and the adjacent cortical bone was calculated. After eight weeks the sheep were slaughtered and a sample of bone was collected for histopathology

RESULTS: Group D showed a higher radiographic ratio than the other groups. Sheep not treated with naloxone showed a persistently lower ratio in the lateral than the medial cortex (P < 0.01). Histopathology of bone samples showed more caverns and fewer osteoblasts in group D than in the other groups (P </= 0.001).

CONCLUSION: A low-dose parenteral regimen of naloxone enhances mineralization and remodelling of the callus in healing cortical defects in sheep, especially if associated with calcium gluconate.

Abstract  Spatial organization of multiple enzymes at specific positions for a controlled reaction cascade has attracted wide attention in recent years. Here, we report the construction of a biomimetic enzyme cascade organized on DNA triangle prism (TP) nanostructures to enable the efficient catalytic production of nitric oxide (NO) on a single microbead. Two enzymes, glucose oxidase (GOx) and horseradish peroxidase (HRP), were assembled at adjacent locations on a DNA TP nanostructure by using DNA-binding protein adaptors with small interenzyme distances. In the cascade, the first enzyme, GOx, converts glucose into gluconic acid in the presence of oxygen. The produced H2 O2 intermediate is rapidly transported to the second enzyme, HRP, which oxides hydroxyurea into NO and other nitroxyl species. The pH near the surface of the negatively charged DNA nanostructures is believed to be lower than that in the bulk solution; this creates an optimal pH environment for the anchored enzymes, which results in higher yields of the NO product. Furthermore, the multienzyme system was immobilized on a microbead mediated by a DNA adaptor, and this enabled the efficient catalytic generation of gas molecules in the microreactor. Therefore, this work provides an alternative route for the biomimetic generation of NO through enzyme cascades. In particular, the dynamic binding capability of the DNA sequence enabled the positions of the protein enzyme and the DNA nanostructure to be reversed, which allowed the cascade catalysis to be modulated.

Abstract  The purification and characterization of a novel extracellular beta-glucosidase from Paecilomyces thermophila J18 was studied. The beta-glucosidase was purified to 105-fold apparent homogeneity with a recovery yield of 21.7% by DEAE 52 and Sephacryl S-200 chromatographies. Its molecular masses were 116 and 197 kDa when detected by SDS-PAGE and gel filtration, respectively. It was a homodimeric glycoprotein with a carbohydrate content of 82.3%. The purified enzyme exhibited an optimal activity at 75 degrees C and pH 6.2. It was stable up to 65 degrees C and in the pH range of 5.0-8.5. The enzyme exhibited a broad substrate specificity and significantly hydrolyzed p-nitrophenyl-beta- d-glucopyranoside ( pNPG), cellobiose, gentiobiose, sophorose, amygdalin, salicin, daidzin, and genistin. Moreover, it displayed substantial activity on beta-glucans such as laminarin and lichenan, indicating that the enzyme has some exoglucanase activity. The rate of glucose released by the purified enzyme from cellooligosaccharides with a degree of polymerization (DP) ranging between 2 and 5 decreased with increasing chain length. Glucose and glucono-delta-lactone inhibited the beta-glucosidase competitively with Ki values of 73 and 0.49 mM, respectively. The beta-glucosidase hydrolyzed pNPG, cellobiose, gentiobiose, sophorose, salicin, and amygdalin, exhibiting apparent Km values of 0.26, 0.65, 0.77, 1.06, 1.39, and 1.45 mM, respectively. Besides, the enzyme showed transglycosylation activity, producing oligosaccharides with higher DP than the substrates when cellooligosaccharides were hydrolyzed. These properties make this beta-glucosidase useful for various biotechnological applications.

Abstract  Pears (Pyrus communis L cv. Conference) may develop core breakdown when stored under low oxygen or elevated carbon dioxide conditions. This physiological disorder is characterized by the development of brown spots due to oxidation of phenolic compounds, and eventually, cavities in the center of the fruit. Based on metabolic profiling of brown and sound tissue using GC-EI-TOF-MS, the hypothesis that this disorder is due to an imbalance between oxidative and reductive processes at the cellular level was investigated. Brown tissue was clearly characterized by a distinctive pattern in changes which included a decrease of malic acid and an increase in fumaric acid and gamma aminobutyric acid (GABA), which indicated a reduced metabolic activity at the level of the Krebs cycle and a putative block of the GABA shunt pathway. Increased gluconic acid concentration might be related to ascorbic acid degradation due to insufficient reducing equivalents or to an impaired pentose phosphate pathway. For the first time, GABA and gluconic acid have been shown to be metabolic markets for core breakdown. The concentrations of other compounds which are believed to be related to hypoxic stress response such as trehalose and putrescine were also considerably higher in brown tissue than in sound tissue. The concentration of some sugars which are typically found in xyloglucans also increased during brown development. possibly indicating cell wall breakdown due to enzymatic processes or chemical reactions of hydroxyl radicals. (C) 2008 Elsevier B.V. All rights reserved.

Abstract  Lipopolysaccharide (LPS), which can cause acute airway inflammatory reactions, constitutes one of the most common substances to establish acute lung injury (ALI) models in mice. Studies suggest that calcium gluconate offers the possibility of suppressing the immune response, and this study was intended to explore the effects of calcium gluconate on LPS-induced ALI in mice. Mice inhaled with LPS were intraperitoneally injected with calcium gluconate (12.5, 25, 50 mg/kg). IL-1β, IL-6 and TNF-α levels in bronchoalveolar lavage fluid (BALF) were determined by ELISA. The expression of signaling proteins, phosphorylation extracellular regulated protein kinases (p-ERK), was detected using Western Blot in lung tissues. In our study, the release of inflammatory cytokines IL-1β, IL-6 and TNF-α in BALF increased after inhalation of LPS. Post-treatment with calcium gluconate inhibited LPS-induced airway inflammatory injury and the release of inflammatory cytokines. In addition, LPS promoted the expression of signaling protein p-ERK while calcium gluconate was capable of reversing this change. Overall, calcium gluconate inhibits LPS-induced ALI in mice, which may take effects through the inhibition of ERK phosphorylation.

Abstract  INTRODUCTION: Micronutrient deficiencies are one of the most important public health issues worldwide and iron (Fe) deficiency anemia is the most prevalent micronutrient deficiency. Iron deficiency often coexists with calcium deficiency and iron and calcium supplementation often overlap. This has led to investigations into the interaction between these two minerals, and whether calcium may inhibit iron absorption in the gut.

OBJECTIVE: To determine the effect of various calcium salts on non-heme iron bioavailability in fasted women of childbearing age.

METHODS: A randomized and single blinded trial was conducted on 27 women of childbearing age (35-45 years old) divided into 2 groups (n1 = 13 and n2 = 14, respectively). On four different days, after an overnight fast, they received 5 mg of Fe as FeSO4 (labeled with 55Fe or 59Fe) with 800 mg of elemental calcium in the form of either calcium chloride, calcium gluconate, calcium citrate, calcium carbonate, calcium lactate, calcium sulfate or calcium phosphate. Calcium chloride was used as the control salt in both groups. Iron was labeled with the radioisotopes 59Fe or 55Fe, and the absorption of iron was measured by erythrocyte incorporation of radioactive Fe RESULTS: 800 mg of elemental calcium as calcium citrate produced a significant decrease in non-heme iron bioavailability (repeated measures ANOVA, F = 3.79, p = 0.018).

CONCLUSION: Of the various calcium salts tested, calcium citrate was the only salt that decreased non-heme iron bioavailability relative to the calcium chloride control when taken on an empty stomach. These results suggest that inhibition of non-heme iron absorption in fasted individuals is dependent upon the calcium salt in question and not solely dependent on the presence of calcium.

Abstract  Floral nectar plays important roles in the interaction between animal-pollinated plants and pollinators. Its components include water, sugars, amino acids, vitamins, and proteins. Growing empirical evidence shows that most of the proteins secreted in nectar (nectarines) are enzymes that can tailor nectar chemistry for their animal mutualists or reduce the growth of microorganisms in nectar. However, to date, the function of many nectarines remains unknown, and very few plant species have had their nectar proteome thoroughly investigated. Mucuna sempervirens (Fabaceae) is a perennial woody vine native to China. Nectarines from this species were separated using two-dimensional gel electrophoresis, and analyzed using mass spectrometry. A L-gulonolactone oxidase like protein (MsGulLO) was detected, and the full length cDNA was cloned: it codes for a protein of 573 amino acids with a predicted signal peptide. MsGulLO has high similarity to L-gulonolactone oxidase 5 (AtGulLO5) in Arabidopsis thaliana, which was suggested to be involved in the pathway of ascorbate biosynthesis; however, both MsGulLO and AtGulLO5 are divergent from animal L-gulonolactone oxidases. MsGulLO was expressed mainly in flowers, and especially in nectary before blooming. However, cloning and gene expression analysis showed that L-galactonolactone dehydrogenase (MsGLDH), a vital enzyme in plant ascorbate biosynthesis, was expressed in all of flowers, roots, stems, and especially leaves. MsGulLO was purified to near homogeneity from raw MS nectar by gel filtration chromatography. The enzyme was determined to be a neutral monomeric protein with an apparent molecular mass of 70 kDa. MsGulLO is not a flavin-containing protein, and has neither L-galactonolactone dehydrogenase activity, nor the L-gulonolactone activity that is usual in animal GulLOs. However, it has weak oxidase activity with the following substrates: L-gulono-1,4-lactone, L -galactono-1,4-lactone, D-gluconic acid-δ-lactone, glucose, and fructose. MsGulLO is suggested to function in hydrogen peroxide generation in nectar but not in plant ascorbate biosynthesis.

Abstract  Bacterial response to environmental stimuli is essential for survival. In response to fluctuating environmental conditions, the physiological status of bacteria can change due to the actions of transcriptional regulatory machinery. The synthesis and accumulation of polyhydroxyalkanoates (PHAs) are one of the survival strategies in harsh environments. In this study, we used transcriptome analysis of Pseudomonas putida KT2440 to gain a genome-wide view of the mechanisms of environmental-friendly biopolymers accumulation under nitrogen-limiting conditions during conversion of metabolically different carbon sources (sodium gluconate and oleic acid). Transcriptomic data revealed that phaG expression is associated with medium-chain-length-PHAs' synthesis not only on sodium gluconate but also on oleic acid, suggesting that PhaG may play a role in this process, as well. Moreover, genes involved in the β-oxidation pathway were induced in the PHAs production phase when sodium gluconate was supplied as the only carbon and energy source. The transition from exponential growth to stationary phase caused a significant expression of genes involved in nitrogen metabolism, energy supply, and transport system. In this study, several molecular mechanisms, which drive mcl-PHAs synthesis, have been investigated. The identified genes may provide valuable information to improve the efficiency of this bioprocess and make it more economically feasible.

Abstract  The synthesis of a range of analogues of the migrastatin macrolide core has been achieved from tri-O-acetyl-D-glucal in order to facilitate structure-activity studies. Efficient macrolactone formation was achieved in the presence of a reactive olefin, by increasing steric hindrance in the olefin environment. Acyclic analogues of migrastatin, structurally related to dorrigocin A, have also been prepared from D-glucal. The dorrigocin A analogues were prepared using the combination of the cross metathesis of ethyl 6-heptenoate with a glycal derivative and a subsequent allylic rearrangement-alkene isomerisation reaction (Perlin reaction). A synthetic route is thus provided that will enable dorrigocin A analogues to be prepared in parallel to migrastatin analogues in the search for novel anti-cancer and anti-arthritic therapeutics. Biological evaluation of one migrastatin and one dorrigocin A sugar derived analogue show that they inhibit proliferation and serum-induced migration of tumour and synovial cells at higher concentrations than evodiamine. Dorrigocin A analogues displayed similar potency to analogues of the migrastatin core.

Abstract  An extracellular beta-glucosidase was purified 154-fold to electrophoretic homogeneity from the brown-rot basidiomycete Fomitopsis palustris grown on 2.0% microcrystalline cellulose. SDS-polyacrylamide gel electrophoresis gel gave a single protein band and the molecular mass of purified enzyme was estimated to be approximately 138 kDa. The amino acid sequences of the proteolytic fragments determined by nano-LC-MS/MS suggested that the protein has high homology with fungal beta-glucosidases that belong to glycosyl hydrolase family 3. The Kms for p-nitorophenyl-beta-D-glucoside (p-NPG) and cellobiose hydrolyses were 0.117 and 4.81 mM, and the Kcat values were 721 and 101.8 per sec, respectively. The enzyme was competitively inhibited by both glucose (Ki= 0.35 mM) and gluconolactone (Ki= 0.008 mM), when p-NPG was used as substrate. The optimal activity of the purified beta-glucosidase was observed at pH 4.5 and 70 degrees. The F. palustris protein exhibited half-lives of 97 h at 55 degrees and 15 h at 65 degrees, indicating some degree of thermostability. The enzyme has high activity against p-NPG and cellobiose but has very little or no activity against p-nitrophenyl-beta-lactoside, p-nitrophenyl-beta-xyloside, p-nitrophenyl-alpha-arabinofuranoside, xylan, and carboxymethyl cellulose. Thus, our results revealed that the beta-glucosidase from F. palustris can be classified as an aryl-beta-glucosidase with cellobiase activity.

Abstract  Red blood cell (RBC)-derived adenosine triphosphate (ATP) has been proposed as an integral component in the regulation of oxygen supply to skeletal muscle. In ex vivo settings RBCs have been shown to release ATP in response to a number of stimuli, including stimulation of adrenergic receptors. Further evidence suggested that ATP release from RBCs was dependent on activation of adenylate cyclase (AC)/cyclic adenosine monophosphate (cAMP)-dependent pathways and involved the pannexin 1 (Panx1) channel. Here we show that RBCs express Panx1 and confirm its absence in Panx1 knockout (-/-) RBCs. However, Panx1-/- mice lack any decrease in exercise performance, challenging the assumptions that Panx1 plays an essential role in increased blood perfusion to exercising skeletal muscle and therefore in ATP release from RBCs. We therefore tested the role of Panx1 in ATP release from RBCs ex vivo in RBC suspensions. We found that stimulation with hypotonic potassium gluconate buffer resulted in a significant increase in ATP in the supernatant, but this was highly correlated with RBC lysis. Next, we treated RBCs with a stable cAMP analog, which did not induce ATP release from wild-type or Panx1-/- mice. Similarly, multiple pharmacological treatments activating AC in RBCs increased intracellular cAMP levels (as measured via mass spectrometry) but did not induce ATP release. The data presented here question the importance of Panx1 for exercise performance and dispute the general assumption that ATP release from RBCs via Panx1 is regulated via cAMP.

Abstract  Penicillium expansum, the causal agent of blue mould rot, is a critical health concern because of the production of the mycotoxin patulin in colonized apple fruit tissue. Although patulin is produced by many Penicillium species, the factor(s) activating its biosynthesis are not clear. Sucrose, a key sugar component of apple fruit, was found to modulate patulin accumulation in a dose-responsive pattern. An increase in sucrose culture amendment from 15 to 175 mm decreased both patulin accumulation and expression of the global regulator laeA by 175- and five-fold, respectively, whilst increasing expression of the carbon catabolite repressor creA. LaeA was found to regulate several secondary metabolite genes, including the patulin gene cluster and concomitant patulin synthesis in vitro. Virulence studies of ΔlaeA mutants of two geographically distant P. expansum isolates (Pe-21 from Israel and Pe-T01 from China) showed differential reduction in disease severity in freshly harvested fruit, ranging from no reduction for Ch-Pe-T01 strains to 15%-25% reduction for both strains in mature fruit, with the ΔlaeA strains of Is-Pe-21 always showing a greater loss in virulence. The results suggest the importance of abiotic factors in LaeA regulation of patulin and other secondary metabolites that contribute to pathogenicity.

Abstract  Efficient optimization of microbial processes is a critical issue for achieving a number of sustainable development goals, considering the impact of microbial biotechnology in agrofood, environment, biopharmaceutical and chemical industries. Many of these applications require scale-up after proof of concept. However, the behaviour of microbial systems remains unpredictable (at least partially) when shifting from laboratory-scale to industrial conditions. The need for robust microbial systems is thus highly needed in this context, as well as a better understanding of the interactions between fluid mechanics and cell physiology. For that purpose, a full scale-up/down computational framework is already available. This framework links computational fluid dynamics (CFD), metabolic flux analysis and agent-based modelling (ABM) for a better understanding of the cell lifelines in a heterogeneous environment. Ultimately, this framework can be used for the design of scale-down simulators and/or metabolically engineered cells able to cope with environmental fluctuations typically found in large-scale bioreactors. However, this framework still needs some refinements, such as a better integration of gas-liquid flows in CFD, and taking into account intrinsic biological noise in ABM.

Abstract  The aim of this study was to compare the effect of fermentation pH on protein bioaccessibility of four soymilk curds enriched with tea polyphenols (TP). The curds were generated by fermentation with Weissella hellenica D1501 and the fermentation terminated at different pH values, namely at pH 5.7, 5.4, 5.1, and 4.8 (SMTP-5.7, SMTP-5.4, SMTP-5.1, SMTP-4.8). Particle-size distribution, soluble protein content, gel electrophoresis, and peptides content were monitored at oral, gastric, and intestinal levels. Results showed that SMTP-4.8 was the matrix most resistant to protein digestion in the gastric phase according to the soluble protein content. Similar particle size distribution and protein degradation patterns were observed for these curds in gastric and intestinal phase. However, there was a significant difference (P < 0.05) in the content of small peptides (<10 kDa) at the end of intestinal digestion among the four curds. Overall, terminating fermentation at pH 5.4-5.7 of soymilk curds enriched with TP is recommended.

Abstract  Currently, American Foulbrood (AFB) represents one of the most important problems for beekeepers, due to economic losses and to the absence of an effective therapeutic treatment. The aim of this work was to characterize fifteen Italian honeys in order to assess their inhibitory activity against Paenibacillus larvae ATCC 9545. Each honesy was analyzed for the activity of the following enzymes: glucose oxidase and catalase. Moreover, melissopalynological analysis and other biochemical parameters, namely gluconic acid, total phenolic and total flavonoid contents were determined. For each honey, the Minimum Inhibitory Concentration (M.I.C.) and the Minimum Bactericidal Concentration (M.B.C.) against P. larvae were determined.

All tested honey samples had an inhibitory activity on P. larvae. In particular, the lowest M.I.C. and M.B.C. values (53.8 mg/mL and 107.5 mg/mL, respectively) were recorded for an Arbutus honey sample. Arbutus honeys also had the highest gluconic acid and total phenolic contents (12.6 +/- 1.7 g/kg and 243.2 +/- 25.1 mg/kg, respectively) and the highest glucose oxidase activity (13.0 +/- 1.9 nM H2O2/min). Dark honeys, including Arbutus, seem to have a higher gluconic acid content and a higher antimicrobial activity. Thus, honey characterization, including colour and physico-chemical characteristics (e.g. gluconic acid concentration, total phenolic and total flavonoid contents, glucose oxidase activity), could be crucial for the assessment of its employment against P. larvae.

Abstract  Sweeteners improve the dietary properties of many foods. A candidate for a new natural sweetener is 5-ketofructose. In this study a fed-batch process for the production of 5-ketofructose was developed. A Gluconobacter oxydans strain overexpressing a fructose dehydrogenase from G. japonicus was used and the sensory properties of 5-ketofructose were analyzed. The compound showed an identical sweet taste quality as fructose and a similar intrinsic sweet threshold concentration of 16.4 mmol/L. The production of 5-ketofructose was characterized online by monitoring of the respiration activity in shake flasks. Pulsed and continuous fructose feeding was realized in 2 L stirred tank reactors and maximum fructose consumption rates were determined. 5-Ketofructose concentrations of up to 489 g/L, product yields up to 0.98 g5-KF/gfructose and space time yields up to 8.2 g/L/h were reached highlighting the potential of the presented process.