101 research outputs found

    Statistical optimization of a culture medium for biomass and poly(3-hydroxybutyrate) production by a recombinant Escherichia coli strain using agroindustrial byproducts

    Get PDF
    A statistically based Plackett-Burman screening design identified milk whey and corn steep liquor concentrations as well as ionic strength (based on phosphate buffer concentration) as the three main independent components of the culture medium that significantly (p < 0.05) influenced biomass and poly(3-hydroxybutyrate) (PHB) production in recombinant cells of Escherichia coli. This strain carries a plasmid encoding phb genes from a natural isolate of Azotobacte sp. Response surface methodology, using a central composite rotatable design, demonstrated that the optimal concentrations of the three components, defined as those yielding maximal biomass and PHB production in shaken flasks, were 37.96 g deproteinated milk whey powder/l, 29.39 g corn steep liquor/l, and 23.76 g phosphates/l (r2 = 0.957). The model was validated by culturing the recombinant cells in medium containing these optimal concentrations, which yielded 9.41 g biomass/l and 6.12 g PHB/l in the culture broth. Similar amounts of PHB were obtained following batch fermentations in a bioreactor. These results show that PHB can be produced efficiently by culturing the recombinant strain in medium containing cheap carbon and nitrogen sources. [Int Microbiol 2005; 8(4):243-250

    The quality assessment of different geolocalisation methods for a sensor system to monitor structural health of monumental objects

    Get PDF
    Cultural heritage objects are affected by a wide range of factors causing their deterioration and decay over time such as ground deformations, changes in hydrographic conditions, vibrations or excess of moisture, which can cause scratches and cracks formation in case of historic buildings. The electromagnetic spectroscopy has been widely used for non-destructive structural health monitoring of concrete structures. However, the limitation of this technology is a lack of geolocalisation in the space for multispectral architectural documentation. The aim of this study is to examine different geolocalisation methods in order to determine the position of the sensor system, which will then allow to georeference the results of measurements performed by this device and apply corrections to the sensor response, which is a crucial element required for further data processing related to the object structure and its features. The classical surveying, terrestrial laser scanning and SfM photogrammetry methods were used in this investigation at three test sites. The methods were reviewed and investigated. The results indicated that TLS technique should be applied for simple structures and plain textures, while the SfM technique should be used for marble-based and other translucent or semi-translucent structures in order to achieve the highest accuracy for geolocalisation of proposed sensor system

    Promoção de uma oferta equitativa no setor dos cuidados continuados integrados: desenvolvimento de uma abordagem multi-período e multiobjetivo para apoio ao planeamento da oferta de cuidados

    Get PDF
    Este estudo propõe um modelo de programação matemática multi‑objetivo e multi‑período para apoiar as decisões de planeamento no setor dos cuida‑ dos continuados integrados (CCI). O modelo proposto permite apoiar o pla‑ neamento da oferta de CCI em regime de internamento, tanto em termos de seleção das melhores localizações para esses serviços, como também da capa‑ cidade a instalar, e isto com o propósito de construir uma rede de cuidados mais equitativa. Serão, assim, considerados três objetivos de equidade – equi‑ dade de acesso, equidade geográfica e equidade socioeconómica. Serão tam‑ bém contabilizados os custos, mas na forma de restrições do modelo. A funçãoobjetivo do modelo incorpora estes múltiplos objetivos de equidade através da atribuição de pesos que são obtidos com recurso à metodologia Measuring Attractiveness by a Category‑Based Evaluation TecHnique (MACBETH). A uti‑ lidade do modelo é ilustrada através da sua aplicação a um caso de estudo na região da Grande Lisboa em Portugal.info:eu-repo/semantics/publishedVersio

    Escherichia coli redox mutants as microbial cell factories for the synthesis of reduced biochemicals

    Get PDF
    Bioprocesses conducted under conditions with restricted O2 supply are increasingly exploited for the synthesis of reduced biochemicals using different biocatalysts. The model facultative aerobe Escherichia coli, the microbial cell factory par excellence, has elaborate sensing and signal transduction mechanisms that respond to the availability of electron acceptors and alternative carbon sources in the surrounding environment. In particular, the ArcBA and CreBC two-component signal transduction systems are largely responsible for the metabolic regulation of redox control in response to O2 availability and carbon source utilization, respectively. Significant advances in the understanding of the biochemical, genetic, and physiological duties of these regulatory systems have been achieved in recent years. This situation allowed to rationally-design novel engineering approaches that ensure optimal carbon and energy flows within central metabolism, as well as to manipulate redox homeostasis, in order to optimize the production of industrially-relevant metabolites. In particular, metabolic flux analysis provided new clues to understand the metabolic regulation mediated by the ArcBA and CreBC systems. Genetic manipulation of these regulators proved useful for designing microbial cells factories tailored for the synthesis of reduced biochemicals with added value, such as poly(3-hydroxybutyrate), under conditions with restricted O2 supply. This network-wide strategy is in contrast with traditional metabolic engineering approaches, that entail direct modification of the pathway(s) at stake, and opens new avenues for the targeted modulation of central catabolic pathways at the transcriptional level

    The review of methods for documentation, management and sustainability of cultural heritage. Case study: Museum of King Jan III’s Palace at Wilanów

    Get PDF
    All countries around the world are blessed with particularly rich cultural heritage. Nowadays, many researchers are exploring different methods for documentation, management and sustainability of cultural heritage. The aim of this article is to review the state of the art documentation, management and sustainability techniques in the field of cultural heritage based on the case study in the Museum of King Jan III’s Palace at Wilanów. Various 2D/3D image- and range-based methods are discussed demonstrating their applications and drawbacks. The geographical information system (GIS) is presented as a method for management, storage and maintenance of cultural heritage documentation

    Optimization of growth media components for polyhydroxyalkanoate (PHA) production from organic acids by Ralstonia eutropha

    Get PDF
    We employed systematic mixture analysis to determine optimal levels of acetate, propionate, and butyrate for cell growth and polyhydroxyalkanoate (PHA) production by Ralstonia eutropha H16. Butyrate was the preferred acid for robust cell growth and high PHA production. The 3-hydroxyvalerate content in the resulting PHA depended on the proportion of propionate initially present in the growth medium. The proportion of acetate dramatically affected the final pH of the growth medium. A model was constructed using our data that predicts the effects of these acids, individually and in combination, on cell dry weight (CDW), PHA content (%CDW), PHA production, 3HV in the polymer, and final culture pH. Cell growth and PHA production improved approximately 1.5-fold over initial conditions when the proportion of butyrate was increased. Optimization of the phosphate buffer content in medium containing higher amounts of butyrate improved cell growth and PHA production more than 4-fold. The validated organic acid mixture analysis model can be used to optimize R. eutropha culture conditions, in order to meet targets for PHA production and/or polymer HV content. By modifying the growth medium made from treated industrial waste, such as palm oil mill effluent, more PHA can be produced.Malaysia. Ministry of Science, Technology and Innovation (MOSTI

    Carbon Metabolism of Enterobacterial Human Pathogens Growing in Epithelial Colorectal Adenocarcinoma (Caco-2) Cells

    Get PDF
    Analysis of the genome sequences of the major human bacterial pathogens has provided a large amount of information concerning their metabolic potential. However, our knowledge of the actual metabolic pathways and metabolite fluxes occurring in these pathogens under infection conditions is still limited. In this study, we analysed the intracellular carbon metabolism of enteroinvasive Escherichia coli (EIEC HN280 and EIEC 4608-58) and Salmonella enterica Serovar Typhimurium (Stm 14028) replicating in epithelial colorectal adenocarcinoma cells (Caco-2). To this aim, we supplied [U-13C6]glucose to Caco-2 cells infected with the bacterial strains or mutants thereof impaired in the uptake of glucose, mannose and/or glucose 6-phosphate. The 13C-isotopologue patterns of protein-derived amino acids from the bacteria and the host cells were then determined by mass spectrometry. The data showed that EIEC HN280 growing in the cytosol of the host cells, as well as Stm 14028 replicating in the Salmonella-containing vacuole (SCV) utilised glucose, but not glucose 6-phosphate, other phosphorylated carbohydrates, gluconate or fatty acids as major carbon substrates. EIEC 4608-58 used C3-compound(s) in addition to glucose as carbon source. The labelling patterns reflected strain-dependent carbon flux via glycolysis and/or the Entner-Doudoroff pathway, the pentose phosphate pathway, the TCA cycle and anapleurotic reactions between PEP and oxaloacetate. Mutants of all three strains impaired in the uptake of glucose switched to C3-substrate(s) accompanied by an increased uptake of amino acids (and possibly also other anabolic monomers) from the host cell. Surprisingly, the metabolism of the host cells, as judged by the efficiency of 13C-incorporation into host cell amino acids, was not significantly affected by the infection with either of these intracellular pathogens

    A Millennium Learning Goal for education post‐2015: a question of outcomes or processes

    Full text link
    As the target year for the current Millennium Development Goal of universal completion of primary education approaches, three World Bank economists have proposed its replacement with a Millennium Learning Goal. This is part of a trend of increased privileging of learning outcomes. The proposal is assessed from the perspective of human rights-based and social justice conceptualisations of education quality. A Millennium Learning Goal may enhance information on inclusion, conceived as equal opportunity to achieve learning outcomes. However, there is a danger that it would be misused to generate high stakes tests that can be detrimental to the achievement of goals that are not readily measurable and hence to the relevance of education. It is argued that a process goal with qualitative targets for the assessment of learning, for the monitoring of educational processes and for the processes by which learning goals are determined would be more appropriate for the international level.As the target year for the current Millennium Development Goal of universal completion of primary education approaches, three World Bank economists have proposed its replacement with a Millennium Learning Goal. This is part of a trend of increased privileging of learning outcomes. The proposal is assessed from the perspective of human rights-based and social justice conceptualisations of education quality. A Millennium Learning Goal may enhance information on inclusion, conceived as equal opportunity to achieve learning outcomes. However, there is a danger that it would be misused to generate high stakes tests that can be detrimental to the achievement of goals that are not readily measurable and hence to the relevance of education. It is argued that a process goal with qualitative targets for the assessment of learning, for the monitoring of educational processes and for the processes by which learning goals are determined would be more appropriate for the international level
    corecore