44,783 research outputs found

    Desarrollo de papeles biocativos por injerto de mol茅culas espec铆ficas en celulosa

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    Tesis (DCI)--FCEFN-UNC, 2019En la presente tesis se presenta el desarrollo de papeles bioactivos con potencial aplicaci贸n en el envasado activo de alimentos. Para tal fin, se propuso el injerto de eugenol, un compuesto de origen natural con propiedades antimicrobiana, antioxidante y repelente de insectos, en celulosa, utilizando 谩cido policarbox铆lico como agente ligante. Con el objetivo de evaluar la escalabilidad del proceso propuesto, se estudiaron distintas tecnolog铆as de curado, tales como calentamiento por convecci贸n, infrarrojo, microondas y conducci贸n. En todos los casos, se analizaron la influencia de las variables operativas sobre el avance de la reacci贸n y propiedades finales del papel preparado, utilizando un dise帽o de experimentos Doehlert para elegir las experiencias a realizar, y analizando los resultados mediante metodolog铆a de superficie de respuesta y an谩lisis estad铆stico ANOVA. Se pudo comprobar que la reacci贸n de injerto de eugenol en papel comercial se produjo con 茅xito en todas las tecnolog铆as estudiadas. Asimismo, se encontraron las condiciones 贸ptimas de reacci贸n para cada una de las tecnolog铆as, para lo cual se busc贸 un compromiso entre el avance de la reacci贸n y las propiedades finales del material (mec谩nicas y color). A partir de estas condiciones, se prepararon papeles y se realiz贸 una caracterizaci贸n m谩s espec铆fica para su aplicaci贸n como envase de alimentos comparando los papeles modificados con el papel virgen. Se analizaron las propiedades mec谩nicas por ensayo de tracci贸n, rasgado y punzonado y se midi贸 la absorci贸n de agua y la capacidad de degradaci贸n. Por otro lado, las propiedades bioactivas analizadas fueron la actividad antioxidante, antimicrobiana, repelente e insecticida de gorgojos (T. castaneum y R. dominica). Una vez probado que el papel modificado presenta buenas caracter铆sticas f铆sicas y bioactivas para su posible aplicaci贸n en el envasado de alimentos, se realizaron prototipos de envasado para harina, como alimento representativo de alimentos derivados de cereales, susceptibles al ataque de plagas. En este estudio se analiz贸 la migraci贸n de reactivos, propiedades organol茅pticas y conservaci贸n del alimento, arrojando resultados promisorios para la industria de envases de alimentos. Finalmente, se realiz贸 una comparaci贸n de las tecnolog铆as de curado ensayadas, analizando diferentes aspectos como avance de reacci贸n, propiedades finales, apariencia, tiempo de reacci贸n, consumo de energ铆a, entre otros, como as铆 tambi茅n disponibilidad y uso de estas tecnolog铆as a escala industrial, seleccionando la tecnolog铆a de conducci贸n como la m谩s adecuada para una propuesta de escalado industrial.Fil: Muratore, Florencia. Universidad Nacional de C贸rdoba. Facultad de Ciencias Exactas, F铆sicas y Naturales; Argentina.Fil: Muratore, Florencia. Consejo Nacional de Investigaciones Cient铆ficas y T茅cnicas. Instituto de Investigaci贸n y Desarrollo en Ingenier铆a de Procesos y Qu铆mica Aplicada; Argentina

    Desarrollo de materiales bioactivos con potencial aplicaci贸n odontol贸gica mediante impregnaci贸n asistida por CO2 supercr铆tico

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    Tesis (DCI)--FCEFN-UNC, 2021En esta tesis se estudi贸 el proceso de incorporaci贸n de eugenol en fibras de poliamida 6 (PA6) mediante la impregnaci贸n asistida por CO2 supercr铆tico para desarrollar un material con propiedades antimicrobianas con una potencial aplicaci贸n odontol贸gica. Para este prop贸sito, se construy贸 un equipo de alta presi贸n en el que se llevaron a cabo m煤ltiples ensayos de impregnaci贸n de eugenol y de sorci贸n de CO2 en un hilo dental comercial de PA6 en distintas condiciones de presi贸n y temperatura (40 鈥 60 掳C y 8 鈥 12 MPa). Con el fin de encontrar las mejores condiciones del proceso de impregnaci贸n, se evalu贸 la influencia de diferentes variables operativas (presi贸n, temperatura, tiempo de contacto y velocidad de despresurizaci贸n) sobre la cantidad de eugenol impregnada en el material. Adem谩s, se estudiaron los principales fen贸menos difusivos que ocurren en el proceso de impregnaci贸n del eugenol en condiciones supercr铆ticas. Para ello, se hicieron ensayos de cin茅tica de sorci贸n del CO2 y del eugenol en PA6 a diferentes condiciones de presi贸n y temperatura y se determin贸 el coeficiente de difusi贸n aparente para ambas especies en este pol铆mero. Por otra parte, se evaluaron las propiedades finales del material impregnado, analizando las propiedades mec谩nicas, t茅rmicas y morfol贸gicas del material original, presurizado con CO2 e impregnado con eugenol. Adicionalmente se evalu贸 la actividad antimicrobiana del material impregnado frente a dos bacterias comunes (Escherichia coli y Staphylococcus aureus). Asimismo, se estudi贸 la migraci贸n del compuesto activo impregnado en aire y en saliva artificial, obteniendo datos importantes para el potencial desarrollo de un producto comercial, como la estimaci贸n de la vida 煤til, el tipo de envase, y tipo de aplicaci贸n del producto. Finalmente, se hizo un dise帽o y dimensionamiento de un proceso industrial para la impregnaci贸n de eugenol en bobinas de fibras de PA6 en CO2 supercr铆tico, a partir de los datos de eficiencia de impregnaci贸n y par谩metros difusivos del hilo impregnado con eugenol previamente obtenidos, realizando el dise帽o de la bobina, el equipo impregnador y los c谩lculos de sus principales requerimientos de masa y energ铆a.Fil: Mosquera Ruiz, Jos茅 Euliser. Universidad Nacional de C贸rdoba. Facultad de Ciencias Exactas, F铆sicas y Naturales; Argentina.Fil: Mosquera Ruiz, Jos茅 Euliser. Consejo Nacional de Investigaciones Cient铆ficas y T茅cnicas. Instituto de Investigaci贸n y Desarrollo en Ingenier铆a de Procesos y Qu铆mica Aplicada; Argentina

    A new index of resilience applicable to external pulse-disturbances that considers the recovery of communities in the short term

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    .Resilience is a key concept in the study of the recovery of ecosystems affected by disturbances. Currently, there are numerous indices to measure resilience, but many of them do not show the accuracy of the resilience value or the behaviour of ecological parameters in the face of disturbances. New approaches and technologies enable large amounts of information to be obtained, facilitating the proposal of new resilience indices that work consistently and intuitively for a wide variety of ecological response variables under different scenarios after pulse-disturbances. In this study, we propose and verify a new resilience index, comparing its performance with others previously published. We validated the performance of the new index using real data based on field measurements of changes in soil bacterial OTUs diversity and abundance after a wildfire. The new resilience index provided an automatic and robust functional classification of the behaviour of ecosystems after disturbances, supported by a bootstrap analysis. We identified 5 scenarios of ecosystem resilience performance according to their behaviour after a pulse-disturbance: resilient, non-resilient, recovering, rebound, and continuing.S

    Effect of salinity stress on antioxidant activity and grain yield of different wheat genotypes

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    In order to evaluate the antioxidant activity of wheat in salinity stress conditions, an experiment with 27 wheat genotypes grown on two types of soil was conducted: solonetz (increased salinity) and chernozem (control), during two vegetation seasons (2015/2016 and 2016/2017). Analysis of DPPH radical scavenging activity and phenolic content (PC) were performed in different phenophases of wheat (tillering, stem elongation and heading). Genotypes showed significantly higher DPPH radical scavenging activity (9.82 mg trolox equivalents (TE) per mg of dry matter (d.m.)) and PC (8.15 mg gallic acid equivalents (GAE) per mg d.m.) under salinity stress conditions compared to values obtained on control (8.52 mg TE mg-1 d.m. and 7.13 mg GAE mg-1 d.m., respectively). All analyzed factors (genotype, soil type and year) had the highly significant influence on phenotypic variation of grain yield. Salinity stress reduced grain yield by 30%, whereas drought stress in 2016/2017 vegetation season reduced grain yield by 20%. Highly significant and positive correlations are present between grain yield and parameters of antioxidant activity in all growth stages of wheat and both soil conditions. Therefore, it could be possible to select salinity tolerant genotypes in early growth stages. DPPH scavenging activity and total phenolic content are in highly significant and positive correlation in all growth stages, which indicates that antioxidant activity is highly derived by phenolics

    Folates: An Introduction

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    Folate is a naturally occurring essential nutrient which is vital for DNA replication and a necessary substrate in various enzymatic reactions which are involved in synthesis of amino acids and vitamin metabolism. The synthetic and oxidized form of folate is folic acid, it is mainly incorporated into fortified foods and dietary supplements for preventive measures against folate deficiency. Folate deficiency has been linked with several abnormalities in both mother (anemia, peripheral neuropathy) and fetus (congenital abnormalities). Folic acid supplementation taken around the time of conception has been known to alleviate the risk of neural tube defects in the off springs. Optimal intake and absorption of folates is required for the maintenance of the human body鈥檚 normal functioning and keeping the genomic integrity intact

    Infarct Stroke and Blood Glucose Associated with Food Consumption in Indonesia

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    Stroke is the primary cause of death in adults. It is predicted that the death caused by stroke will increase twice in the next 30聽years. In Indonesia, stroke is one of the diseases of the circulatory system, which has been taking the first place of causing death since 2007. Indonesia has rice as the main type of daily food consumed, which has higher glycemic index than other sources. This study aims to find the risk of blood glucose level that determines the incidence of infarct stroke. There were 164 patients enrolled in this study, 82 patients in each stroke and not stroke group. The blood examination is using the enzymatic method, which is the hexokinase method. The results of research revealed that indicators of high blood glucose level were found in infract stroke incidence, including casual blood glucose, fasting blood glucose, 2-h postprandial blood glucose, and glycated hemoglobin. These four indicators were found in a higher level in the infarct stroke than the non-stroke group. Other epidemiological studies have shown that diabetes is a risk factor for stroke. Therefore, education about food selection should be a priority in the effort to prevent infarct stroke and diabetes mellitus in Indonesia

    Valorization of lignocellulosic wastes for extracellular enzyme production by novel Basidiomycetes: screening, hydrolysis, and bioethanol production

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    This study aimed at the exploitation of lignocellulosic wastes for the evaluation of the newly isolated white-rot fungal strains enzymatic potential for bioethanol production. The isolates belonging to Basidiomycetes, Fomes fomentarius TMF2, Schizophyllum commune TMF3, and Bjerkandera adusta TMF1, could synthesize extracellular laccase and various hydrolase while growing on lignocellulosic waste materials. More specifically, for the first time, F. fomentarius TMF2 synthesized laccase using sunflower meal as a substrate. This substrate could stimulate B. adusta TMF1 for carboxymethyl cellulase and Avicelase production. The isolate B. adusta TMF1 was able to produce amylase during its growth on brewer's spent grain, which is up to now the best result reported for this activity of any B. adusta strain. Soybean meal was the most potent substrate for stimulating pectinase production by B. adusta TMF1 and S. commune TMF3. While growing on brewer 's spent grain, B. adusta TMF1 and S. commune TMF3 produced high levels of xylanase. Spent coffee residues were for the first time tested as a substrate for hydrolase production by selected fungal species. Also, this is the first attempt where the produced enzymes by isolate B. adusta TMF1 were used for lignocellulose hydrolysis of brewer's spent grain and corn stover for bioethanol production, where under non-optimized conditions 0.94 g/L and 0.86 g/L of bioethanol could be produced, respectively. This study showed that novel white-rot fungal isolates, especially B. adusta TMF1, could grow on unexploited, low-cost lignocellulosic substrates and to produce biotechnological value-added products within environmental and economical accepted processes

    Diversidade e potencial biotecnol贸gico de fungos marinhos da Ria de Aveiro

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    Although knowledge about the ecological group of lignicolous marine fungi is still scarce, especially in Portugal, it is known that they play an essential ecological role in marine and estuarine ecosystems, namely in the degradation of organic matter present in wood and consequent contributing to the functioning of the aquatic 鈥渕icrobial ring鈥 that drives the biogeochemical cycles and the maintenance of trophic relationships. In addition to their environmental contribution, they are also a source of compounds with biotechnological potential, with applications in various industrial and pharmaceutical areas. In this study, in order to investigate the occurrence of lignicolous marine fungi in the estuary of Ria de Aveiro, blocks of wood (Pinus pinaster) were submerged in a marina, for one year. Seventeen different fungal species were successfully identified, with a high prevalence of species belonging to the family Lulwortiaceae. Through phylogenetic analyses based on the ribosomal ITS (internal transcribed spacer), LSU (large ribosomal subunit) and SSU (small ribosomal subunit) regions combined with morphological and physiological studies, two genera (Lulworthiopsis and Marinomyces) were introduced to accommodate Lulworthia cf. purpurea and Papulaspora halima, respectively. In the same way, Lulworthiopsis maritima sp. nov., Halosphaeria submersa sp. nov. and Zalerion pseudomaritima sp. nov. were proposed as novel species. To assess their biotechnological potential, isolates of interest were selected and enzymatic and antibacterial tests were carried out. As expected from lignicolous species, most isolates tested positive for cellulolytic and pectinolytic activities. Halosphaeria submersa, M. halima and Z. maritima revealed an interesting potential in several extracellular enzymatic activities. Differences were also detected in enzyme production in the presence and absence of salt, thus proposing that these activities can be stimulated or inhibited depending on the salinity. Regarding the results of antibacterial activity, the selected isolates showed more effective against Gram-positive bacteria. Lulworthiopsis purpurea and M. halima showed antibacterial activity against the multiresistant Gram-negative bacteria of Pseudomonas aeruginosa and Klebsiella pneumoniae, respectively, representing an anti-bacterial potential effective in combating these pathogenic strains. Future taxonomic and biotechnological studies focused on lignicolous marine fungi may bring benefits to several areas of research.Apesar de o conhecimento relativo ao grupo ecol贸gico dos fungos marinhos lenh铆colas ser ainda escasso, especialmente em Portugal, 茅 sabido que possuem um papel ecol贸gico essencial nos ecossistemas marinhos e estuarinos, nomeadamente na degrada莽茫o da mat茅ria org芒nica presente na madeira e consequente contribui莽茫o para o funcionamento do 鈥渁nel microbiano鈥 aqu谩tico que impulsiona os ciclos biogeoqu铆micos e a manuten莽茫o das rela莽玫es tr贸ficas. Para al茅m do seu contributo ambiental s茫o tamb茅m uma fonte de compostos com potencial biotecnol贸gico, com aplica莽玫es em v谩rias 谩reas industriais e farmac锚uticas. Neste trabalho, de modo a investigar a ocorr锚ncia de fungos marinhos lenh铆colas no estu谩rio da Ria de Aveiro, blocos de madeira (Pinus pinaster) foram submersos numa marina, durante um ano. Dezassete esp茅cies de fungos diferentes foram identificadas com sucesso, observando-se uma predomin芒ncia de esp茅cies pertencentes 脿 fam铆lia Lulwortiaceae. Atrav茅s de an谩lises filogen茅ticas baseadas nas regi玫es do DNA ribossomal ITS (internal transcribed spacer), LSU (large subunit ribossomal) e SSU (small subunit ribosomal) conjugadas com estudos morfol贸gicos e fisiol贸gicos foram introduzidos dois g茅neros (Lulworthiopsis e Marinomyces) para acomodar Lulworthia cf. purpurea e Papulaspora halima, respetivamente. De igual modo, Lulworthiopsis maritima sp. nov., Halosphaeria submersa sp. nov. e Zalerion pseudomaritima sp. nov. s茫o propostas como esp茅cies novas. Para avaliar as suas potencialidades biotecnol贸gicas, isolados de interesse foram selecionados e realizaram-se testes enzim谩ticos e antibacterianos. Como era esperado de esp茅cies lenh铆colas, a maioria dos isolados testaram positivo para as atividades celulol铆ticas e pectinol铆ticas. Halosphaeria submersa, M. halima e Z. maritima revelaram um interessante potencial em v谩rias atividades enzim谩ticas extracelulares. Foram ainda detetadas diferen莽as na produ莽茫o enzim谩tica na presen莽a e aus锚ncia de sal, sugerindo assim que estas atividades possam ser estimuladas ou inibidas consoante a salinidade. Em rela莽茫o aos resultados da atividade antibacteriana, os isolados selecionados apresentaram uma maior efic谩cia contra bact茅rias Gram-positivo. Lulworthiopsis purpurea e M. halima mostraram atividade antibacteriana contra as bact茅rias Gram-negativo multirresistentes Pseudomonas aeruginosa e Klebsiella pneumoniae, respetivamente, representando um potencial antibacteriano eficaz no combate a estas esp茅cies patog茅nicas. Futuros estudos taxon贸micos e biotecnol贸gicos focados em fungos marinhos lenh铆colas podem vir a trazer benef铆cios para diversas 谩reas de investiga莽茫o.Mestrado em Microbiologi

    Bioinformatic characterization of a triacylglycerol lipase produced by Aspergillus flavus isolated from the decaying seed of Cucumeropsis mannii

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    Lipases are enzymes of industrial importance responsible for the hydrolysis of ester bonds of triglycerides. A lipolytic fungus was isolated and subsequently identified based on the ITS sequence analysis as putative Aspergillus flavus with accession number LC424503. The gene coding for extracellular triacylglycerol lipase was isolated from Aspergillus flavus species, sequenced, and characterised using bioinformatics tools. An open reading frame of 420 amino acid sequence was obtained and designated as Aspergillus flavus lipase (AFL) sequence. Alignment of the amino acid sequence with other lipases revealed the presence GHSLG sequence which is the lipase consensus sequence Gly-X1-Ser-X2-Gly indicating that it a classical lipase. A catalytic active site lid domain composed of TYITDTIIDLS amino acids sequence was also revealed. This lid protects the active site, control the catalytic activity and substrate selectivity in lipases. The 3-Dimensional structural model shared 34.08% sequence identity with a lipase from Yarrowia lipolytica covering 272 amino acid residues of the template model. A search of the lipase engineering database using AFL sequence revealed that it belongs to the class GX-lipase, superfamily abH23 and homologous family abH23.02, molecular weight and isoelectric point values of 46.95鈥塊Da and 5.7, respectively. N-glycosylation sites were predicted at residues 164, 236 and 333, with potentials of 0.7250, 0.7037 and 0.7048, respectively. O-glycosylation sites were predicted at residues 355, 358, 360 and 366. A signal sequence of 37 amino acids was revealed at the N-terminal of the polypeptide. This is a short peptide sequence that marks a protein for transport across the cell membrane and indicates that AFL is an extracellular lipase. The findings on the structural and molecular properties of Aspergillus flavus lipase in this work will be crucial in future studies aiming at engineering the enzyme for biotechnology applications
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