963 research outputs found

    Technologically important properties of lactic acid bacteria isolated from raw milk of three breeds of Algerian dromedary (Camelus dromedarius)

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    A total of 9 samples of individual dromedary raw milks from N’ajjer (3), Targui (3) and Reguibi (3) breeds were collected from 3 camels nomad herd in south Algeria and were analysed for bacterial load. A totalof 23 strains of lactic acid bacteria were isolated, out of which 12 strains were cocci and 11 strains were facultatively heterofermentative lactobacilli. Lactic acid bacteria were identified on the basis ofphenotypic characters as Lactococcus lactis subsp. lactis, Enterococcus faecalis, Enterococcus faecium, Enterococcus durans, Lactobacillus paracasei subsp. paracasei, Lactobacillus plantarum andLactobacillus rhamnosus. Whole cells of lactococci, enterococci and lactobacilli showed proteolytic activity and were found to differed in terms of their acidifying activities. Proteolytic and autolyticactivity were generally higher for most lactobacilli compared to other isolates and none of the strains produced biogenic amines in the method applied. A wide variety of this 23 lactic acid bacteria strainsisolated from Algerian dromedary milks that showed potentially important properties suggest that they are good candidate for camels milk processing or other dairy fermentation process

    Lactic acid bacteria isolated from fermented green olives produced in Western Algeria

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    Vingt trois isolats de bactéries lactiques ont été isolés à partir de 10 échantillons d’olives vertes fermentées dans l’ouest algérien. Elles ont été caractérisées et identifiées sur la base de l’observation microscopique, des propriétés biochimiques et la capacité de fermentation des sucres. Onze souches étaient identifiées à l’espèce Lactobacillus plantarum, 7 à l’espèce Enterococcus faecium et 5 à l’espèce Lactococcus lactis ssp. lactis. Cette étude préliminaire a pour objectif l’élaborationd’une collection locale de culture bactériènnes starters

    Identification of lactic acid bacteria isolated from milk and fermented olive oil in western Algeria

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    Un total de 154 souches de Lactococcus, Lactobacillus, Enterococcus ou Streptococcus ont été isolées à partir d’échantillons d’huile d’olive ou d’échantillons de laits crus de vache, de chèvre et de brebis collectés dans l’ouest algérien. Les tests de caractérisation morphologiques et biochimiques ont permis d’identifier 50 souches de Lc. lactis subsp. lactis, 34 souches de Lc. lactis subsp. biovar. diacetylactis et 35 souches de Lc. lactis subsp. cremoris. Vingt et une souches ont été identifiées comme étant des Lactobacillus sp., 11 souches des Enterococcus faecium et 03 souches des Streptococcus bovis

    Optical properties of metal nanoparticles with no center of inversion symmetry: observation of volume plasmons

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    We present theoretical and experimental studies of the optical response of L-shaped silver nanoparticles. The scattering spectrum exhibits several plasmon resonances that depend sensitively on the polarization of the incident electromagnetic field. The physical origin of the resonances is traced to different plasmon phenomena. In particular, a high energy band with unusual properties is interpreted in terms of volume plasmon oscillations arising from the asymmetry of a nanoparticle.Comment: 14 pages, 5 figures. Physical Review B, 2007, accepte

    Mejora de la producción de lípidos de un prometedor hongo oleaginoso Aspergillus sp. cepa EM2018 para la formación de biodiesel: optimización de las condiciones de cultivo e identificación

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    Oleaginous fungi have recently gained increasing attention among different microorganisms due to their ability for lipid production for the preparation of biofuel. In the present study, a locally isolated fungus E45, identified genetically as Aspergillus sp. strain EM2018, was found to produce 25.2% of the total lipids content of its dry cell weight (DCW). Optimization of culture conditions was performed and lipid accumula­tion increased by about 2.4 fold (from 25.2% to 60.1% of DCW) when the fungus was grown for seven days in the potato dextrose (50 g/L) liquid medium at pH 5.0, incubation temperature at 30 ºC and inoculum size of 2 × 106 spore/mL. Supplementation of the medium with yeast extract and NaNO3 at a concentration of 0.05% as organic and inorganic nitrogen sources, respectively, increased lipid production (53.3% lipid/dry biomass). Gas chromatography analysis of fungal lipids revealed the presence of saturated (mainly palmitic acid C16:0 (33%) and lignoceric acid C24:0 (15%)) and unsaturated fatty acids in different proportions (mainly linoleic acid C18:2 (24.4%), oleica cid C18:1 (14%) and arachidonic C20:4 (7.4%). These findings suggest this new oleaginous fungus as a promising feedstock for various industrial applications and for the preparation of biodiesel.Los hongos oleagino­sos recientemente están ganando una creciente atención entre diferentes microorganismos debido a sus capaci­dades de producción de lípidos para la preparación de biocombustibles. En el presente estudio, se descubrió que un hongo E45 aislado localmente, identificado genéticamente como la cepa Aspergillus sp. EM2018, produce un 25,2% de lípidos totales de su peso de células secas (DCW). Se realizó la optimización de las condiciones de cultivo y la acumulación de lípidos se incrementó aproximadamente 2,4 veces (del 25,2% al 60,1% de DCW) cuando el hongo creció durante siete días en un medio líquido de dextrosa de papa (50 g/L) a pH 5.0, 30 °C de temperatura de incubación y 2 × 106 esporas/ml de tamaño de inóculo. La suplementación del medio con extracto de leva­dura y NaNO3 a una concentración de 0,05% como fuentes de nitrógeno orgánico e inorgánico, respectivamente, aumentó aún más la producción de lípidos (53,3% de lípidos/biomasa seca). El análisis mediante cromatografía de gases de los lípidos fúngicos reveló la presencia de ácidos grasos saturados (principalmente palmítico C16:0 (33%) y lignocérico C24:0 (15%)) y ácidos grasos insaturados en diferentes proporciones (principalmente linoleico C18:2 (24.4%), oleico C18:1 (14%) y araquidónico C20:4 (7,4%). Estos hallazgos sugieren que este nuevo hongo oleaginoso es una materia prima prometedora para diversas aplicaciones industriales y preparación de biodiésel

    Impact of Long-Term Forest Enrichment Planting on the Biological Status of Soil in a Deforested Dipterocarp Forest in Perak, Malaysia

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    Deforestation leads to the deterioration of soil fertility which occurs rapidly under tropical climates. Forest rehabilitation is one of the approaches to restore soil fertility and increase the productivity of degraded areas. The objective of this study was to evaluate and compare soil biological properties under enrichment planting and secondary forests at Tapah Hill Forest Reserve, Perak after 42 years of planting. Both areas were excessively logged in the 1950s and left idle without any appropriate forest management until 1968 when rehabilitation program was initiated. Six subplots (20 m × 20 m) were established within each enrichment planting (F1) and secondary forest (F2) plots, after which soil was sampled at depths of 0–15 cm (topsoil) and 15–30 cm (subsoil). Results showed that total mean microbial enzymatic activity, as well as biomass C and N content, was significantly higher in F1 compared to F2. The results, despite sample variability, suggest that the rehabilitation program improves the soil biological activities where high rate of soil organic matter, organic C, N, suitable soil acidity range, and abundance of forest litter is believed to be the predisposing factor promoting higher population of microbial in F1 as compared to F2. In conclusion total microbial enzymatic activity, biomass C and biomass N evaluation were higher in enrichment planting plot compared to secondary forest. After 42 years of planting, rehabilitation or enrichment planting helps to restore the productivity of planted forest in terms of biological parameters

    Deep phenotyping of cardiac function in heart transplant patients using cardiovascular system models

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    Heart transplant patients are followed with periodic right heart catheterizations (RHCs) to identify post‐transplant complications and guide treatment. Post‐transplant positive outcomes are associated with a steady reduction of right ventricular and pulmonary arterial pressures, toward normal levels of right‐side pressure (about 20 mmHg) measured by RHC. This study shows that more information about patient progression is obtained by combining standard RHC measures with mechanistic computational cardiovascular system models. The purpose of this study is twofold: to understand how cardiovascular system models can be used to represent a patient’s cardiovascular state, and to use these models to track post‐transplant recovery and outcome. To obtain reliable parameter estimates comparable within and across datasets, we use sensitivity analysis, parameter subset selection, and optimization to determine patient‐specific mechanistic parameters that can be reliably extracted from the RHC data. Patient‐specific models are identified for 10 patients from their first post‐transplant RHC, and longitudinal analysis is carried out for five patients. Results of the sensitivity analysis and subset selection show that we can reliably estimate seven non‐measurable quantities; namely, ventricular diastolic relaxation, systemic resistance, pulmonary venous elastance, pulmonary resistance, pulmonary arterial elastance, pulmonary valve resistance and systemic arterial elastance. Changes in parameters and predicted cardiovascular function post‐transplant are used to evaluate the cardiovascular state during recovery of five patients. Of these five patients, only one showed inconsistent trends during recovery in ventricular pressure–volume relationships and power output. At the four‐year post‐transplant time point this patient exhibited biventricular failure along with graft dysfunction while the remaining four exhibited no cardiovascular complications.Key pointsRight heart catheterization data from clinical records of heart transplant patients are used to identify patient‐specific models of the cardiovascular system.These patient‐specific cardiovascular models represent a snapshot of cardiovascular function at a given post‐transplant recovery time point.This approach is used to describe cardiac function in 10 heart transplant patients, five of which had multiple right heart catheterizations allowing an assessment of cardiac function over time.These patient‐specific models are used to predict cardiovascular function in the form of right and left ventricular pressure‐volume loops and ventricular power, an important metric in the clinical assessment of cardiac function.Outcomes for the longitudinally tracked patients show that our approach was able to identify the one patient from the group of five that exhibited post‐transplant cardiovascular complications.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156242/2/tjp14120.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156242/1/tjp14120_am.pd
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