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1.
Nat Commun ; 14(1): 1653, 2023 Mar 24.
Article in English | MEDLINE | ID: mdl-36964152

ABSTRACT

Improving the performance of molecular qubits is a fundamental milestone towards unleashing the power of molecular magnetism in the second quantum revolution. Taming spin relaxation and decoherence due to vibrations is crucial to reach this milestone, but this is hindered by our lack of understanding on the nature of vibrations and their coupling to spins. Here we propose a synergistic approach to study a prototypical molecular qubit. It combines inelastic X-ray scattering to measure phonon dispersions along the main symmetry directions of the crystal and spin dynamics simulations based on DFT. We show that the canonical Debye picture of lattice dynamics breaks down and that intra-molecular vibrations with very-low energies of 1-2 meV are largely responsible for spin relaxation up to ambient temperature. We identify the origin of these modes, thus providing a rationale for improving spin coherence. The power and flexibility of our approach open new avenues for the investigation of magnetic molecules with the potential of removing roadblocks toward their use in quantum devices.

2.
Article in English | MEDLINE | ID: mdl-35270265

ABSTRACT

In this study, chestnut shells (CNS), a recalcitrant and low-value agro-industrial waste obtained during the peeling of Castanea sativa fruits, were subjected to solid-state fermentation by six white-rot fungal strains (Irpex lacteus, Ganoderma resinaceum, Phlebia rufa, Bjerkandera adusta and two Trametes isolates). After being fermented, CNS was subjected to hydrolysis by a commercial enzymatic mix to evaluate the effect of fermentation in saccharification yield. After 48 h hydrolysis with 10 CMCase U mL−1 enzymatic mix, CNS fermented with both Trametes strains was recorded with higher saccharification yield (around 253 mg g−1 fermented CNS), representing 25% w/w increase in reducing sugars as compared to non-fermented controls. To clarify the relationships and general mechanisms of fungal fermentation and its impacts on substrate saccharification, the effects of some independent or explanatory variables in the production of reducing sugars were estimated by general predictive saccharification models. The variables considered were lignocellulolytic activities in fungal fermentation, CNS hydrolysis time, and concentration of enzymatic hydrolysis mix. Multiple linear regression analysis revealed a very high significant effect (p < 0.0001) of fungal laccase and xylanase activities in the saccharification models, thus proving the key potential of these enzymes in CNS solid-state fermentation.


Subject(s)
Laccase , Trametes , Fermentation , Hydrolysis , Sugars
3.
Biodegradation ; 32(3): 287-298, 2021 06.
Article in English | MEDLINE | ID: mdl-33772685

ABSTRACT

Vinasse from the distillation of winemaking residues is a wastewater characterized by high levels of aromatic compounds. Batch cultures of Phlebia rufa showed a significant (p < 0.05) correlation between laccase activity and initial vinasse concentration. The pattern of biodegradation of hydroxybenzoic acids, hydroxycinnamic acids and flavonoids, assessed by HPLC-DAD, revealed that p-hydroxybenzoic acid is the most recalcitrant compound. Vinasse-induced laccase showed electrophoretic homogeneity and molecular weight of 62 kDa after being purified 21-fold. Optimum pH for oxidation of 2,6-dimethoxyphenol (2,6-DMP) was 3.5 and optimum temperature was 50 °C, with an activation energy of 42.8 kJ mol-1. Catalytic efficiency of 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) oxidation is about two orders of magnitude higher than 2,6-DMP oxidation, being their Km values 36.2 ± 2.6 µM and 303.0 ± 44.7 µM, respectively and kcat values 486.1 s-1 and 179.6 s-1, respectively. Akaike information criterion and Akaike weights were used to discriminate inhibition models that best fitted 2,6-DMP oxidation in the presence of inhibitors. Inhibition constants of mixed-type inhibitors azide and fluoride, and competitive-type inhibitor chloride, showed the following inhibitors potency: azide > fluoride > chloride. Taken together, this study is consistent with the assumption that P. rufa could be a useful tool for aerobic degradation of phenolic-rich wastewaters.


Subject(s)
Laccase , Biodegradation, Environmental , Hydrogen-Ion Concentration , Kinetics , Laccase/metabolism , Polyporales , Temperature
4.
Article in English | MEDLINE | ID: mdl-32823843

ABSTRACT

Grape stalks, an inedible lignocellulosic residue from winemaking and agro-industrial grape juice production, can be valorized as a source of bioactive compounds and as feedstock for the saccharification and bioconversion of soluble sugars. Solid-state fermentation (SSF) by six white-rot fungi was applied as pretreatment. Fiber composition, free radical scavenging activity, four ligninolytic, and three hydrolytic enzyme activities were determined. Saccharification kinetics, yield, and productivity were evaluated and complemented with scanning electron microscopy (SEM), high performance liquid chromatography (HPLC) quantification of monosaccharides, and principal component analysis (PCA). After SSF, the biomass exhibited a drastic free radical scavenging activity decrease and the main enzymes produced were manganese-dependent peroxidase and xylanase. Scanning electron microscopy revealed the erosion of cell walls, and PCA exhibited a negative correlation between saccharification, and neutral detergent fiber and acid detergent lignin. Phlebia rufa pretreated biomass gave the highest sugars yield and productivity, representing a nearly three-fold increase compared to untreated samples. Also, monosaccharides quantification revealed that the 1:1 ratio of glucose to the sum of xylose plus galactose changes to the value of 2:1 after pretreatment. In this work, and for the first time, P. rufa proved to be an effective pretreatment of grape stalks for the saccharification and further bioconversion into value-added chemicals. In addition, lignocellulolytic enzymes were also produced through SSF.


Subject(s)
Monosaccharides , Vitis/microbiology , Biomass , Carbohydrates , Fermentation , Kinetics , Lignin/metabolism , Vitis/metabolism
5.
Chemosphere ; 238: 124572, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31422312

ABSTRACT

The wastewaters from distilleries of winemaking by-products, a scarcely studied type of vinasse, were treated by white-rot fungal strains from species Irpex lacteus, Ganoderma resinaceum, Trametes versicolor, Phlebia rufa and Bjerkandera adusta. The main objectives of this study were to evaluate fungal performance during vinasse biodegradation, their enzyme patterns and ecotoxicity evolution throughout treatment. Despite all strains were able to promote strong (>80%) dephenolization and reduction of total organic carbon (TOC), P. rufa was less affected by vinasse toxicity and exhibit better decolorization. In batch cultures at 28 °C and pH 4.0, the first phase of P. rufa biodegradation kinetics was characterized by strong metabolic activity with simultaneous depletion of TOC, phenolics and sugars. The main events of second phase are the increase of peroxidases production after the peak of laccase activity, and strong color removal. At the end of treatment, it was observed highly significant (p < 0.001) abatement of pollution parameters (83-100% removal). Since water reclamation and reuse for e.g. crop irrigation is a priority issue, vinasse ecotoxicity was assessed with bioindicators representing three different phylogenetic and trophic levels: a marine bacterium (Aliivibrio fischeri), a freshwater microcrustacean (Daphnia magna) and a dicotyledonous macrophyte (Lepidium sativum). It was observed significant (p < 0.05) reduction of initial vinasse toxicity, as evaluated by these bioindicators, deserving special mention an almost complete phytotoxicity elimination.


Subject(s)
Aliivibrio fischeri/growth & development , Coriolaceae/metabolism , Daphnia/growth & development , Lepidium sativum/growth & development , Polyporales/metabolism , Trametes/metabolism , Wastewater/chemistry , Wastewater/toxicity , Aliivibrio fischeri/metabolism , Animals , Biodegradation, Environmental , Daphnia/metabolism , Distillation , Environmental Biomarkers/drug effects , Laccase/metabolism , Lepidium sativum/metabolism , Peroxidases/metabolism , Phenols/metabolism , Phylogeny
6.
Appl Biochem Biotechnol ; 191(2): 657-665, 2020 Jun.
Article in English | MEDLINE | ID: mdl-31845192

ABSTRACT

This study describes the development of a new methodology based on a new integrated equation which allows the determination of the kinetic parameters for two mutually non-exclusive inhibitors when one of which is produced during the time-course reaction. Alkaline phosphatase simultaneously inhibited by phosphate and urea is used to illustrate this methodology, including the evaluation of interaction effects between them. Data analyses were carried out using two integrated velocity equations: exclusive linear mixed inhibition (EMI) and non-exclusive linear mixed inhibition (NEMI). Kinetic parameters are estimated using non-linear regression and results show that (i) the interaction between enzyme and the inhibitors urea and phosphate exhibit a mutually non-exclusive behavior; (ii) more specifically, these inhibitors are non-exclusive only in free enzyme (E) species; (iii) the inhibitors also show an interaction with enzyme classified as facilitation; (iv) phosphate is a competitive inhibitor and urea a mixed inhibitor; (v) the inhibition constant for phosphate is much lower than that determined for urea. In addition, a functional Excel Spreadsheet which can be adapted to any kinetic study is also included as a supplement.


Subject(s)
Alkaline Phosphatase/drug effects , Enzyme Inhibitors/pharmacology , Binding, Competitive , Drug Interactions , Kinetics , Models, Chemical , Phosphates/antagonists & inhibitors , Urea/antagonists & inhibitors
7.
Ecotoxicol Environ Saf ; 183: 109493, 2019 Nov 15.
Article in English | MEDLINE | ID: mdl-31376802

ABSTRACT

Vinasses obtained from the distillation of winemaking by-products (WDV) are complex effluents with variable physicochemical properties. Frequently, WDVs are used to irrigate agricultural soil, and/or discharged into aquatic bodies, which may result in serious environmental pollution, due to the presence of organic acids and recalcitrant compounds (polyphenols, tannins and metals). The present study aimed to evaluate the toxicity impact of an untreated WDV on terrestrial and aquatic organisms, at different levels of biological organization. The effluent was collected at the distillation column exit and characterized according to several physicochemical properties. The WDV potential phytotoxicity was assessed by germination inhibition assays on six agricultural crops, and its acute toxicity was assessed on Aliivibrio fisheri (microtox assay), Daphnia magna neonates (freshwater crustacean), and zebrafish Danio rerio (fish embryo toxicity test, FET). The WDV presented a low pH (3.88), high levels of electrical conductivity, ECond (6.36 dS m-1) and salinity (3.3 ppt), besides high level of potassium (2.1 g L-1) and organic compounds (TOC = 17.7 g L-1), namely polyphenols (1.7 g L-1). The diluted WDV displayed variable inhibitory effects on the plant endpoints (percentage of inhibition of germination and radicle elongation and germination index). Overall, plants' susceptibility to increasing concentrations of WDV were differential (onion ≈ garden cress ≥ tomato > lettuce > maize > green beans) and the germination index EC50 varied from 10.9 to 64.4% v/v. Also, the acute negative effects toward aquatic organisms were determined, decreasing from the more complex organism to the simpler one: zebrafish embryos (96 h-LC50 = 0.34% v/v)>D. magna (48 h-LC50 = 4.8% v/v)>A. fisheri (30min-EC50 = 7.0% v/v). In conclusion, the findings suggest that WDVs might have a high toxicological impact on both terrestrial plants and aquatic organisms, even at high dilution levels, reinforcing the need for appropriate treatments before considering its discharge or reuse.


Subject(s)
Aquatic Organisms/drug effects , Industrial Waste , Plants/drug effects , Water Pollutants, Chemical/toxicity , Wine , Animals , Aquatic Organisms/growth & development , Germination/drug effects , Lethal Dose 50 , Organic Chemicals/chemistry , Plants/classification , Toxicity Tests , Water Pollutants, Chemical/chemistry
8.
Sci Rep ; 8(1): 15943, 2018 10 29.
Article in English | MEDLINE | ID: mdl-30374188

ABSTRACT

Forested wetlands are interfaces between terrestrial and aquatic environments. These ecosystems play an important role in the hydrology, chemistry and biodiversity maintenance. Despite their high microbial diversity, there has been a lack of attention to the potential of their yeast communities. The purpose of this study is to evaluate the potential of yeasts isolated from a Mediterranean forested wetlands in decolorizing azo dyes. Azo dyes are synthetic, and highly recalcitrant to degradation. Ninety-two out of 560 isolates were randomly chosen to assess their ability to decolorize five azo dyes. Hierarchical clustering based on medium color changes during incubations was used to evaluate the isolates' decolorization performance. All of the isolates that best degraded the 5 dyes tested were identified as Basidiomycota (Filobasidiales, Tremellales and Sporidiobolales). This work identifies new azo dye-degrading yeast species, and supports the hypothesis that forested wetlands are a niche for yeasts with bioremediation potential - namely azo dyes removal.


Subject(s)
Azo Compounds/metabolism , Basidiomycota/metabolism , Biodegradation, Environmental , Basidiomycota/classification , Basidiomycota/isolation & purification , Biomass , Cluster Analysis , Ecosystem , Phylogeny , Wetlands
9.
Comput Methods Programs Biomed ; 125: 2-7, 2016 Mar.
Article in English | MEDLINE | ID: mdl-26777432

ABSTRACT

To determine initial velocities of enzyme catalyzed reactions without theoretical errors it is necessary to consider the use of the integrated Michaelis-Menten equation. When the reaction product is an inhibitor, this approach is particularly important. Nevertheless, kinetic studies usually involved the evaluation of other inhibitors beyond the reaction product. The occurrence of these situations emphasizes the importance of extending the integrated Michaelis-Menten equation, assuming the simultaneous presence of more than one inhibitor because reaction product is always present. This methodology is illustrated with the reaction catalyzed by alkaline phosphatase inhibited by phosphate (reaction product, inhibitor 1) and urea (inhibitor 2). The approach is explained in a step by step manner using an Excel spreadsheet (available as a template in Appendix). Curve fitting by nonlinear regression was performed with the Solver add-in (Microsoft Office Excel). Discrimination of the kinetic models was carried out based on Akaike information criterion. This work presents a methodology that can be used to develop an automated process, to discriminate in real time the inhibition type and kinetic constants as data (product vs. time) are achieved by the spectrophotometer.


Subject(s)
Enzyme Inhibitors/chemistry , Catalysis , Kinetics
10.
Carbohydr Polym ; 111: 936-46, 2014 Oct 13.
Article in English | MEDLINE | ID: mdl-25037434

ABSTRACT

In this work the effect of carbon and nitrogen levels and initial pH of the wheat extract culture medium of submerged culture of Ganoderma lucidum on the amount, purity and structural features of exopolysaccharides (EPS) were studied. A low peptone level (1.65 g L(-1)) favored mycelium biomass, EPS purity, but a higher supply of peptone (4.80 g L(-1)) is needed for maximum EPS production. The carbohydrate composition of the EPS and structural features also changed significantly according to the different growing conditions, being observed significant differences in the (1 → 3)/(1 → 4)-Glcp ratio and also on the branching degree of EPS. As the biological activities of EPS are highly dependent on the polysaccharide structural features, this variability can have implications on the EPS biological activities, but can also be used advantageously to produce tailor made polysaccharides with specific applications.


Subject(s)
Culture Media/metabolism , Polysaccharides/chemistry , Reishi/chemistry , Reishi/growth & development , Biomass , Cell Culture Techniques/methods , Culture Media/chemistry , Hydrogen-Ion Concentration , Polysaccharides/metabolism , Reishi/metabolism
11.
Chemosphere ; 117: 53-8, 2014 Dec.
Article in English | MEDLINE | ID: mdl-24968162

ABSTRACT

Winery wastewaters (WW) have high levels of organic matter, resulting in high COD and BOD and suspended solids. This paper studies the combination of biological and chemical processes in WW treatment. Among 10 yeast isolates, Filobasidium sp. (AGG 577) and Cryptococcus laurentii (AGG 726) were selected due to their superior performance in COD removal. During WW degradation, COD and total polyphenols (TPP) content removal of 89-90% for Filobasidium sp. and 90-93% for C. laurentii were obtained. However, despite similar degradation efficiency for both yeasts, COD kinetics and pH evolution during treatment reveals that C. laurentii presents a faster response than Filobasidium sp. The toxicity (inhibition of Vibrio fischeri luminescence) of C. laurentii treated WW decreases to an inhibition value below 2.5%. However, treated WW exceeds the legal limits, making necessary an additional treatment. In this case, the selection of Fenton's reagent as a chemical final polish step process is a good compromise between efficiency and lower practical complexity. The best results for both COD and TPP removal were obtained with H2O2 initial concentration of 39.2mM and a H2O2:Fe(2+) molar ratio of 15:1. The combined C. laurentii - Fenton's reagent treatment of WW achieved a total reduction of 98% and 96%, for COD and TPP, respectively.


Subject(s)
Cryptococcus/growth & development , Hydrogen Peroxide/chemistry , Iron/chemistry , Vitis/growth & development , Wastewater/chemistry , Water Pollutants, Chemical/analysis , Water Purification/methods , Biological Oxygen Demand Analysis , Hydrogen-Ion Concentration , Kinetics , Wastewater/microbiology
12.
Appl Biochem Biotechnol ; 169(6): 1919-26, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23354498

ABSTRACT

Fungi have been used for medicinal purposes for long time by Asian countries, being a putative source of powerful new phytopharmaceuticals such as polysaccharides. The aim of this study was to extract endopolysaccharides (IPS) from Ganoderma resinaceum, Phlebia rufa, and Trametes versicolor, grown under submerged culture, to compare crude IPS production, total carbohydrate, and protein yield, and to study the effect of these IPS on HepG2 cells proliferation rate. Total biomass produced by G. resinaceum, P. rufa, and T. versicolor was (in gram per liter) 3.32 ± 0.80, 5.42 ± 0.58, and 4.2 ± 1.29 and the IPS yield (as the biomass percent) was 9.9 ± 0.05, 29.0 ± 6.3, and 9.1 ± 3.1 %, respectively. Characterization of IPS has shown different proportion between total sugar and protein being, on average 6.04, 10.74, and 22.62, for G. resinaceum, T. versicolor, and P. rufa, respectively. The IPS effect, at 50, 100, and 200 µg mL(-1) on HepG2 cell growth and viability was negligible for G. resinaceum and P. rufa but, in the case of T. versicolor, 200 µg mL(-1) of IPS evoked 40 % reduction on cell growth. The results suggest that the intracellular polysaccharides from T. versicolor are a potential source for bioactive molecules with anti-proliferative properties.


Subject(s)
Antineoplastic Agents/isolation & purification , Antineoplastic Agents/pharmacology , Fungal Polysaccharides/isolation & purification , Fungal Polysaccharides/pharmacology , Ganoderma/chemistry , Trametes/chemistry , Antineoplastic Agents/chemistry , Carbohydrates/analysis , Cell Proliferation/drug effects , Cell Survival/drug effects , Fungal Polysaccharides/chemistry , Fungal Proteins/analysis , Ganoderma/cytology , Hep G2 Cells , Humans , Intracellular Space/chemistry , Trametes/cytology
13.
Comput Methods Programs Biomed ; 109(1): 26-31, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23021091

ABSTRACT

Enzyme kinetic parameters are usually determined from initial rates nevertheless, laboratory instruments only measure substrate or product concentration versus reaction time (progress curves). To overcome this problem we present a methodology which uses integrated models based on Michaelis-Menten equation. The most severe practical limitation of progress curve analysis occurs when the enzyme shows a loss of activity under the chosen assay conditions. To avoid this problem it is possible to work with the same experimental points utilized for initial rates determination. This methodology is illustrated by the use of integrated kinetic equations with the well-known reaction catalyzed by alkaline phosphatase enzyme. In this work nonlinear regression was performed with the Solver supplement (Microsoft Office Excel). It is easy to work with and track graphically the convergence of SSE (sum of square errors). The diagnosis of enzyme inhibition was performed according to Akaike information criterion.


Subject(s)
Enzyme Inhibitors/chemistry , Enzymes/chemistry , Software , Alkaline Phosphatase/antagonists & inhibitors , Alkaline Phosphatase/chemistry , Catalysis , Enzymes/metabolism , Kinetics , Nitrophenols/chemistry , Organophosphorus Compounds/chemistry
14.
Ciudad Autónoma de Buenos Aires; Ministerio de Salud de la Nación; 2013. 1 p.
Non-conventional in Spanish | ARGMSAL, BINACIS | ID: biblio-1537729

ABSTRACT

INTRODUCCIÓN Organismos gubernamentales de Nación y Provincia de Buenos Aires (PBA) producen contenidos audiovisuales (CAV) de salud. OBJETIVOS Analizar CAV producidos en 2010-2014 por TV abierta e Internet, evaluando su adecuación a lo establecido en planes y programas de salud y la perspectiva de usuarios, efectores y gestores. MÉTODOS Diseño exploratorio-descriptivo cualicuantitativo, con triangulación de análisis de contenidos, revisión de programas, cuestionarios y auditorías. La muestra estuvo constituida por 144 CAV y 79 documentos (planes y programas) del Ministerio de Salud de la Nación y de la PBA, con 410 encuestados (51% usuarios, 40% efectores, 9% gestores) y 2 auditorías. RESULTADOS De los CAV analizados, sólo el 28% apela a la función poética del lenguaje. El 44,9% refiere enfermedades transmisibles; 22,9% salud sexual y reproductiva (SSR); 22% prevención/promoción; 18,6% vacunación; 16,1% derechos/equidad; 12,7% enfermedades no transmisibles, etc. El 45% se dirige a la población general. Los destinatarios particulares son madres 15,3%, mujeres en edad fértil 14,4%, embarazadas 11,9%, etc. Menos del 40% se dirigen a destinatarios contextuados; el 60%, a uno abstracto y universal; el 90%, a un sujeto de aprendizaje sin saberes previos; el 96% supone incorporación mecánica del contenido del mensaje. No se observan cuidadores, a excepción de bebés/niños acompañados. El propósito es de prevención (55,9%), promoción (32,2%) y asistencia (11,9%). No hay diversidad regional; un 4,2% menciona grupos minoritarios. Los contenidos identificados como prioritarios por los usuarios son prevención/promoción 53,9%, SSR 44,7%, adicciones 31,8%, alimentación 28,4%, etc. DISCUSIÓN Las concepciones de los CAV se sustentan en el modelo hegemónico. Los planes y programas priorizan contenidos de promoción de la salud. Las auditorías señalan las diferencias más importantes entre demanda y tratamiento en temas de enfermedades no transmisibles, alimentación e higiene, agua y medio ambiente.


Subject(s)
Public Policy , Health Education , Communications Media , Video-Audio Media , Health Promotion
15.
Bioresour Technol ; 111: 261-7, 2012 May.
Article in English | MEDLINE | ID: mdl-22406100

ABSTRACT

Solid state and submerged fermentations in the presence of white-rot basidiomycetes (Bjerkandera adusta, Fomes fomentarius, Ganoderma resinaceum, Irpex lacteus, Phanerochaete chrysosporium, Trametes versicolor and basidiomycete Euc-1) and the litter-decomposing basidiomycete Lepista nuda were evaluated as a pretreatment to increase enzymatic saccharification of wheat straw. Enzymatic hydrolysis of holocellulose after solid state pretreatment showed a significant (P<0.05) increase of saccharification process for T. versicolor, Euc-1, G. resinaceum and I. lacteus, being T. versicolor (strain Tv2) the best one with a sugar yield increase of 91% compared with untreated straw. In submerged medium the pretreatment with I. lacteus, Euc-1 and P. chrysosporium enhanced saccharification but at a lesser extent. Covariance analysis was used to evaluate the relationships between ligninolytic enzymes (lignin peroxidase, manganese-dependent peroxidase and laccase) and saccharification increase. Results showed that only the presence of lignin peroxidase during pretreatment can lead to a significant (P<0.05) increase in the saccharification yield.


Subject(s)
Basidiomycota/metabolism , Enzymes/metabolism , Lignin/metabolism , Hydrolysis
16.
Appl Biochem Biotechnol ; 165(1): 178-89, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21499786

ABSTRACT

In order to establish which are the contribution of linear (total), hyperbolic (partial) or parabolic inhibitions by cellobiose, and also a special case of substrate inhibition, the kinetics of cellobiohydrolase Cel7A obtained from Trichoderma reesei was investigated. Values of kinetic parameters were estimated employing integrated forms of Michaelis-Menten equations through the use of non-linear regression, and criteria for selecting inhibition models are discussed. With cellobiose added at the beginning of the reaction, it was found that cellulose hydrolysis follows a kinetic model, which takes into account a mixed hyperbolic inhibition, by cellobiose with the following parameter values: K (m) 5.0 mM, K (ic) 0.029 mM, K (iu) 1.1 mM, k (cat) 3.6 h(-1) and k (cat') 0.2 h(-1). Cellulose hydrolysis without initial cellobiose added also follows the same inhibition model with similar values (4.7, 0.029 and 1.5 mM and 3.2 and 0.2 h(-1), respectively). According to Akaike information criterion, more complex models that take into account substrate and parabolic inhibitions do not increase the modulation performance of cellulose hydrolysis.


Subject(s)
Cellulose 1,4-beta-Cellobiosidase/metabolism , Cellulose/metabolism , Cellulase/metabolism , Hydrolysis , Kinetics , Substrate Specificity
17.
Bioresour Technol ; 101(15): 6045-50, 2010 Aug.
Article in English | MEDLINE | ID: mdl-20307975

ABSTRACT

Wheat straw was submitted to a pre-treatment by the basidiomycetous fungi Euc-1 and Irpex lacteus, aiming to improve the accessibility of cellulose towards enzymatic hydrolysis via previous selective bio-delignification. This allowed the increase of substrate saccharification nearly four and three times while applying the basidiomycetes Euc-1 and I. lacteus, respectively. The cellulose/lignin ratio increased from 2.7 in the untreated wheat straw to 5.9 and 4.6 after the bio-treatment by the basidiomycetes Euc-1 and I. lacteus, respectively, thus evidencing the highly selective lignin biodegradation. The enzymatic profile of both fungi upon bio-treatment of wheat straw have been assessed including laccase, manganese-dependent peroxidase, lignin peroxidase, carboxymethylcellulase, xylanase, avicelase and feruloyl esterase activities. The difference in efficiency and selectivity of delignification within the two fungi treatments was interpreted in terms of specific lignolytic enzyme profiles and moderate xylanase and cellulolytic activities.


Subject(s)
Cellulose/metabolism , Endo-1,4-beta Xylanases/chemistry , Fungi/metabolism , Plant Components, Aerial/chemistry , Plant Components, Aerial/microbiology , Triticum/chemistry , Triticum/microbiology , Carbohydrate Metabolism/physiology , Lignin/metabolism
18.
J Laparoendosc Adv Surg Tech A ; 19(6): 731-4, 2009 Dec.
Article in English | MEDLINE | ID: mdl-19792865

ABSTRACT

OBJECTIVE: The aim of this work was to establish reliable parameters of the correct position of the Veress needle in the peritoneal cavity during creation of pneumoperitoneum. METHODS: The Veress needle was inserted into the peritoneal cavity of 100 selected patients, and a carbon-dioxide flow rate of 1.2 L/min and a maximum pressure of 12 mm Hg were established. Intraperitoneal pressure (IP) and the volume of gas injected (VG) were recorded at the beginning of insufflation and at every 20 seconds. Correlations were established for pressure and volume in function of time. Values of IP and VG were predicted at 1, 2, 3, and 4 minutes of insufflation, by applying the following formulas: IP = 2.3083 + 0.0266 x time +8.3 x 10(-5) x time(2) - 2.44 x 10(-7) x time(3); and VG = 0.813 + 0.0157 x time. RESULTS: A strong correlation was observed between IP and preestablished time points during creation of the pneumoperitoneum, as well as between VG and preestablished time points during creation of the pneumoperitoneum, with a coefficient of determination of 0.8011 for IP and of 0.9604 for VG. The predicted values were as follows: 1 minute = 4.15; 2 minutes = 6.27; 3 minutes = 8.36; and 4 minutes = 10.10 for IP (mm Hg); and 1 minute = 1.12; 2 minutes = 2.07; 3 minutes = 3.01; and 4 minutes = 3.95 for VG (L). CONCLUSIONS: Values of IP and VG at given time points during insufflation for creation of the pneumoperitoneum, using the Veress needle, can be effective parameters to determine whether the needle is correctly positioned in the peritoneal cavity.


Subject(s)
Carbon Dioxide/administration & dosage , Insufflation/instrumentation , Monitoring, Intraoperative/methods , Needles/adverse effects , Pneumoperitoneum, Artificial/instrumentation , Pressure , Adult , Aged , Dose-Response Relationship, Drug , Drug Administration Schedule , Female , Humans , Male , Middle Aged , Pneumoperitoneum, Artificial/adverse effects , Predictive Value of Tests , Reproducibility of Results
19.
Bioresour Technol ; 100(20): 4829-35, 2009 Oct.
Article in English | MEDLINE | ID: mdl-19450975

ABSTRACT

The potential of crude enzyme extracts, obtained from solid state cultivation of four white-rot fungi (Trametes versicolor, Bjerkandera adusta, Ganoderma applanatum and Phlebia rufa), was exploited to modify wheat straw cell wall. At different fermentation times, manganese-dependent peroxidase (MnP), lignin peroxidase (LiP), laccase, carboxymethylcellulase (CMCase), avicelase, xylanase and feruloyl esterase activities were screened and the content of lignin as well as hydroxycinnamic acids in fermented straw were determined. All fungi secreted feruloyl esterase while LiP was only detected in crude extracts from B. adusta. Since no significant differences (P>0.05) were observed in remaining lignin content of fermented straw, LiP activity was not a limiting factor of enzymatic lignin removal process. The levels of esterified hydroxycinnamic acids degradation were considerably higher than previous reports with lignocellulosic biomass. The data show that P. rufa, may be considered for more specific studies as higher ferulic and p-coumaric acids degradation was observed for earlier incubation times.


Subject(s)
Basidiomycota/metabolism , Fermentation , Lignin/metabolism , Triticum/metabolism , Basidiomycota/enzymology , Coumaric Acids/metabolism , Esterases/metabolism , Esterification , Hydrolysis , Phenols/analysis , Time Factors
20.
Article in English | MEDLINE | ID: mdl-18642152

ABSTRACT

Winery wastewaters (WW) are characterized by their high organic load and by the presence of non-biodegradable compounds such as phenolic compounds. This study was undertaken to evaluate the capacity of different Advanced Oxidation Processes (AOP) combined with several radiation sources to degrade the phenolic compound Gallic Acid (GA). A toxicological assessment was also carried out to evaluate the subproduct's harmful effect generated during the most efficient AOP in the GA photoxidation. Through the course of the study it was verified that the UV radiation lamp TNN 15/32 showed the capacity to degrade 34.7% of GA, the UV radiation lamp TQ 150 achieved a value of 20.2% and the solar radiation presented only a value of 2.3% in 60 minutes. The combination of different advanced oxidation processes (Fenton's reagent, ferrioxalate and heterogeneous photocatalysis) were evaluated with the previously studied sources of radiation. From the experiments conducted it was possible to suggest that the AOP in combination with Fe(2 +) + H(2)O(2) + UV TNN 15/32 (photo-Fenton process) was the most efficient process thereby achieving the GA degradation value of 95.6% in 7.5 minutes and resulting in a total elimination of toxicity.


Subject(s)
Food Industry , Gallic Acid/chemistry , Industrial Waste , Photochemistry , Wine , Aliivibrio fischeri/drug effects , Hydrogen Peroxide/chemistry , Oxidation-Reduction , Titanium/chemistry , Ultraviolet Rays , X-Ray Diffraction
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