Percorrer por autor "Moreira, P. R."
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- Attempts in enzymatic degradation of the pigmentation produced by fungi isolated from Portuguese wall paintingsPublication . Marco, A.; Moreira, P. R.; Pintado, M.; Vieira, E.Wall paintings are prone to different types of deterioration, including of biological origin. Our study focuses on the chromatic alterations of the paintings’ surfaces related to the presence and growth of microorganisms. The removal of the dark coloured stains from wall paintings is extremely difficult. Although treatment with biocides can eliminate microorganisms, these compounds are ineffective in cleaning the black pigmentation resulting of their growth. Therefore, it is necessary to understand which organisms are present, the characteristics of the compounds they generate, and in which conditions they produce it. The aim of this study was to isolate the pigment that is the source of the black stains in the studied wall paintings in order to, in a broader scope, eliminate or attenuate their visual impact. Wall paintings presenting black stains from three case studies – Igreja de Santa Eulália/Igreja de São Salvador de Arnoso (V.N. Famalicão), Igreja Paroquial de Valadares (Baião) and Igreja de Santa Cristina de Serzedelo (Guimarães) were dully studied from the conservation point of view. Fungi were isolated from selected areas that displayed dark pigmentation of the pictorial layer. Samples were collected with wet swabs and grown on solid culture medium, e.g. Potato Dextrose Agar (PDA). Isolates were further identified by classical and molecular biology methodologies. Three fungal isolates were selected for further studies due to their pigmentation and growth characteristics, mainly: blackening of solid culture media, dark or black hyphae growth, or a presence of black exudates produced by colourless hyphae. Enzymatic degradation of pigmentation resulting from a selected fungal isolates was attempted both in solution and on solid support and tested with fungal versatile peroxidase from Bjerkandera adusta. Changes in colour were detected by UV-Vis spectrophotometry and with a CIE L*a*b system colorimeter.
- Development of a workflow for generic protein sequence analysis using Taverna Workbench softwarePublication . Monteiro, M. B.; Pintado, M. E.; Shadforth, I.; Malcata, F. Xavier; Moreira, P. R.
- Enzymatic degradation of fungal pigmentation from Wall painting’s isolatesPublication . Marco, A.; Moreira, P. R.; Pintado, M. E.; Vieira, EduardaEnzymatic discolouration of extracellular pigments produced in liquid media by a selected fungal isolate from Portuguese mural paintings was attempted both in solution and on solid support. A promising versatile peroxidase from Bjerkandera adusta was tested and presented interesting discolouration ability, although smaller than the values obtained with the use of hydrogen peroxide alone.
- Intron phase analysis for Bjerkandera sp. versatile peroxidase genePublication . Moreira, P. R.; Malcata, F. X.; Duarte, J. C.
- Isolation and characterisation of a new Bjerkandera sp. strain B33/3 peroxidasePublication . Moreira, P. R.; Almeida-Vara, E.; Malcata, F. X.; Duarte, J. C.
- Isolation and screening of yeast strains possessing synthetic dye decolorizing activityPublication . Silva, A. R. S.; Vaz, M. J. S.; Kwiatkowska, B.; Malcata, F. Xavier; Pintado, M. E.; Moreira, P. R.
- Isolation and screening of yeast strains possessing synthetic dye decolorizing activityPublication . Silva, A. R. S.; Vaz, M. J. S.; Kwiatkowska, B.; Malcata, F. Xavier; Pintado, M. E.; Moreira, P. R.Synthetic dyes are organic compounds that have been extensively used for textile dyeing and paper printing, as well as additives in petroleum, pharmaceutical and cosmetic products. However, owing to their aromatic and heterocyclic moieties, synthetic dyes are often highly recalcitrant and some are even toxic and mutagenic. Because of their resistance to microbial degradation, dyes can cause considerable environmental pollution, so their removal has received considerable attention. Many microorganisms have been found to be capable of degrading dyes; these include bacteria, filamentous fungi, yeasts, actinomycetes and algae. White rot fungi, in particular, are able to transform (and even mineralize) some dyes, based on their extracellular, non-specific and non-stereoselective enzyme systems. Involvement of ligninolytic peroxidases (viz. Versatile, MnP and LiP), besides laccases, has been demonstrated in the degradation pathways of some of those dyes. However, filamentous fungi are poorly adapted to a continuous wastewater treatment unit, due to their low rates of growth, coupled with a filamentous exuberant mycelium. Yeasts possess the advantage of growing faster than filamentous fungi, and can in addition resist to unfavorable environments. However, degradation of synthetic dyes by yeasts has not been extensively reported to date. Reporting this communication, the process of isolation of wild yeasts from wastewater treatment plants, and subsequent screening (along with other 81 cheese isolates), for the ability of decolorizing textile dyes is reported — covering solid media. Three isolates were further tested for dye decolorization in liquid cultures. In liquid culture the yeast isolate LIIIS36 exhibited a high efficiency of decolorization in the case of two of the dyes tested (Levafix Red CA and Levafix Yellow CA). The observation of colorless yeast cells might unfold the existence of an underlying biodegradation mechanism. The possibility to decolorize more than one dye simultaneously with the same strain (LIIIS36), and the fact that the maximum decolorization extent is reached in a mere 24—36 hours of incubation, are clues for its potential as part of future bioremediation strategies.
- Lignin transformation: role of a new versatile peroxidase from a Bjerkandera sp.Publication . Duarte, J. C.; Sena-Martins, G.; Almeida-Vara, E.; Malcata, F. Xavier; Moreira, P. R.
- Screening and identification of yeast strains possessing synthetic dye-decolorizing and ligninolytic activitiesPublication . Silva, A. R. S.; Soares, J.; Moreira, P. R.; Pintado, M. E.