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- Response surface evaluation of microwave-assisted extraction conditions for Lycium barbarum bioactive compoundsPublication . Mendes, Marta; Carvalho, Ana P.; Magalhães, Júlia M. C. S.; Moreira, Manuela; Guido, Luís; Gomes, Ana M. P.; Delerue-Matos, CristinaThe effects of microwave-assisted extraction (MAE) on the qualitative and quantitative composition of extracted bioactive phytochemicals are strongly dependent on specific operational conditions. The impact of temperature, extraction time, and solvent dielectric properties on theMAE of antioxidant compounds fromgoji berry is hereby reported and discussed. Results were evaluated in terms of antioxidant capacity (ascertained by ABTS and ORAC assays), complemented with quantification of total phenolics content (TPC), and characterization of extracts through HPLC. Furthermore, the effect of storage temperature was also studied. Results revealed that temperature and solvent properties exert a significant effect on TPC and ORAC assays, whereas irradiation time plays a key role in the preparation of extracts to be evaluated through ABTS. The effect of solvent properties is tentatively explained considering the dielectric properties ofmethanol andwater,whereas the observed effect of temperature could be explained by its influence on the solubility of phenolic compounds. Industrial Relevance: A careful selection of operational conditions duringMAE, designed for a specific antioxidant assay, allows an increase in the bioactivity of the resultant extracts,which may become important in terms of industrial applications.
- Decolorization of textile dyes and effluents by a selected yeast and preliminary characterization of the product metabolitesPublication . Cassoni, Carolina; Mendes, Marta; Moreira, Patrícia; Castro, Paula; Pintado, Manuela
- Antimicrobial, antiadhesive and antibiofilm activity of an ethanolic, anthocyanin-rich blueberry extract purified by solid phase extractionPublication . Silva, Sara; Costa, Eduardo M.; Mendes, M.; Morais, R. M. S. C.; Calhau, Conceição; Pintado, M. E.Aims: The present work aimed to characterize the impact of an anthocyaninrich blueberry extract upon the growth, adhesion and biofilm formation of several pathogens including some multiresistant bacteria. Methods and Results: A group comprised of reference strains and clinical multiresistant isolates of Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, Acinetobacter baumannii and Staphylococcus aureus, were used to screen for antimicrobial activity. Microbial growth was determined through the measurement of the optical density while adhesion and biofilm formation was determined using the standard crystal violet staining procedure. The results showed that, while blueberry extract was only effective in hindering the growth of Staph. aureus and E. coli, it was capable of significantly inhibiting biofilm formation and bacterial adhesion for all micro-organisms tested. Conclusions: The extract demonstrated a considerable potential as a natural, alternative antimicrobial capable of either interfering with microbial growth or hamper the adhesion to surfaces, with Staph. aureus proving to be the most susceptible micro-organism. Significance and Impact of the Study: The overall study demonstrates the potential of anthocyanin extracts as natural effective alternative antimicrobial agents. Additionally, the extract’s capacity to reduce adhesion without reducing bacterial growth reduces the likeliness of resistance development while reducing the probability of infection.
- Microwave-assisted extraction in goji berries: effect on composition and bioactivity, evaluated through conventional and nonconventional methodologiesPublication . Carvalho, Ana P.; Mendes, Marta; Moreira, Manuela M.; Cruz, Diana; Magalhães, Júlia M. C. S.; Barroso, M. Fátima; Ramalhosa, M. J.; Duarte, Abel; Guido, Luís; Gomes, Ana M. P.; Matos, Cristina DelerueThis study aimed to evaluate the effect of microwave-assisted extraction (MAE) parameters on the composition and bioactivity of goji (Lycium barbarum) extracts. Extracts were obtained under a central composite design combination of experimental conditions, and characterised through HPLC-DAD; their bioactive capacity was ascertained for antimicrobial and antioxidant capacity, the later by spectrophotometric [2,2-azinobis (3- ethylbenzothiazoline-6-sulfonic acid) diammonium salt-radical scavenging activity assay – 413–748 mg ascorbic acid equivalents/100 g DW and oxygen radical absorbance capacity – 1901–2292 mg trolox equivalents/ 100 g DW] and electrochemical (DNA-based sensor – 3571–6602 mg ascorbic acid/100 g DW) methods. The quantitative profile of phenolic compounds was strongly dependent on MAE conditions. Significant correlations were found between the presence of several flavonoids and solvent composition, as well as between phenolic acids with methoxy group and the response to DNA-based sensor. Results may improve targeted extractions for specific compounds, leading to the achievement of extracts richer in antioxidant capacity, as well as in the tailoring of the biosensor response sensitivity to the composition of the extracts under analysis.
- Assessment of drying conditions of a yeast-based solution for application on textile industrial wastewater treatment plantsPublication . Mendes, Marta; Cassoni, Ana C.; Moreira, Patrícia R.; Pintado, Manuela E.; Castro, Paula M. L.
- Evaluation of decolourisation of reactive dyes by selected yeasts and related enzymatic activityPublication . Mendes, Marta; Cassoni, Carolina; Moreira, Patrícia; Castro, Paula; Pintado, Manuela
- Toxicity of decolourisation products of synthetic textile effluents by a selected yeastPublication . Mendes, Marta; Cassoni, Carolina; Moreira, Patrícia; Pintado, Manuela; Castro, Paula
- Dye decolorization by yeasts : insights on pathways towards an innovative solution for textile effluentsPublication . Mendes, Marta Sofia de Almeida; Castro, Paula Maria Lima e; Pintado, Maria Manuela Estevez; Costa, Patricia Raquel Fernandes de Melo Moreira daThe textile industry produces high amounts of effluents containing synthetic dyes that are recalcitrant, toxic, potentially hazardous to the environment, and difficult to treat by conventional methods. Biotechnological approaches are generally considered more environmentally friendly and biological methods for dye degradation need to be further investigated. The work described in this PhD thesis aimed to develop a yeast-based solution to decolorize textile dyed effluents that can be safely discharged into the environment. Yeast strains Candida parapsilosis (HOMOGS20B), Yarrowia lipolytica (HOMOGST27AB) and Candida pseudoglaebosa (LIIIS36B), isolated from wastewater treatment plants, were tested for their ability to decolorize textile dyes. A total of 32 commercial textile synthetic dyes and simulated textile effluents were tested with the target yeasts (single strains and consortia) and the decolorization was evaluated spectrophotometrically for 48-72 hours. Yeasts were able to perform decolorization through adsorption and biodegradation for 28 of the dyes and simulated effluents to extents higher than 50%. Y. lipolytica (HOMOGST27AB) and C. pseudoglaebosa (LIIIS36B) presented true decolorization of reactive dyes, above 90% at 100 mg/L, and of simulated effluents at 5 g/L of concentration. Enzyme production was evaluated: oxidoreductase was found in the three yeasts, whereas tyrosinase was only found in Y. lipolytica (HOMOGST27AB) and C. pseudoglaebosa (LIIIS36B). The potential toxicity of the dyed simulated effluents, before and after treatment, was investigated. The toxicity of the yeast-treated effluents was assessed using three different assays to represent different trophic levels. Mutagenicity was also evaluated. C. pseudoglaebosa (LIIIS36B) was the most effective strain, completely decolorizing four of the five simulated effluents. Degradation products, possibly aromatic amines, were detected in the supernatant. Although the toxicity of the original simulated effluents was considered high, treated effluents demonstrated a decrease in toxicity and none exhibited mutagenicity. A yeast-based solution for decolorization of textile industrial wastewater was assessed. The three yeast strains previously selected for their dye decolorization capacity were freeze-dried. Additionally, Y. lipolytica (HOMOGST27AB) was also spray-dried. Skim milk powder and maltodextrin were used as cell protectors, and the freeze-dried products were stored at cold (4 °C) and room temperature for 210 days. The viability of the yeast cells and their decolorization capacity over time were assessed. Dried yeast cells maintained their viability and decolorization capacity for at least 90 days of storage after spray- and freeze-drying with both cell-protecting agents. The dried yeast-based solution for decolorizing textile industrial wastewater combines stability, efficiency, and convenience of production for application in real industrial facilities. A sequencing batch reactor (SBR) inoculated with activated sludge and successfully bioaugmented with the dye-decolorizing yeast strain – Y. lipolytica (HOMOGST27AB) was assembled. The bioaugmented AGS-SBR was operated for the treatment of a synthetic saline wastewater (12 g/L) intermittently fed with the reactive textile dye (Navy Everzol ED) at 25, 15, and 7.5 mg/L. Dye degradation did not occur although some dye adsorbed to the granules. AGS-SBR performance in removing carbon and nitrogen was effective and was not affected by the dye addition. The AGS core microbiome gathered essentially microorganisms from the Proteobacteria and Bacteroidetes phyla. The microbial profile showed a dynamic microbiome established at Phase I of the operation, with a high decrease in abundance of Ignavibacterium from the initial biomass to the granules formed and an increase of Actinobacteria, Cytophagia, Flavobacteria, and Alphaproteobacteria in the remaining phases of the bioreactor operation. The bioaugmented yeast remained present throughout the entire reactor process. Y. lipolytica (HOMOGST27AB) and C. pseudoglaebosa (LIIIS36B) are a potential biotechnological tool for dye degradation in textile wastewaters, especially those containing reactive dyes and a promising tool to integrate in bioremediation solutions, contributing to eco sustainability in the water sector, but further operational scenarios need to be researched.
- Preliminary evaluation of decolourisation of procion and everdirect dyes by yeastsPublication . Mendes, Marta; Moreira, Patrícia; Castro, Paula; Pintado, Manuela