Browsing by Author "Oliveira, Ana Sofia"
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- An eco-friendly and up-scalable approach to extract canthaxanthin from yeast cellsPublication . Pereira, Ana M.; Durão, Joana; Pereira, Joana Odila; Ferreira, Carlos; Faustino, Margarida; Oliveira, Ana Sofia; Pereira, Carla F.; Pintado, Manuela E.; Carvalho, Ana P.Canthaxanthin is a naturally occurring ketocarotenoid pigment present in plants, algae, bacteria and some fungi. In addition to its coloring role, canthaxanthin has an excellent antioxidant activity, thus having additional market demands in the feed, food, cosmetic and pharmaceutical industries. Canthaxanthin can be directly isolated from its natural source or produced by chemical synthesis, but these strategies either result in low yields, or use hazardous solvents, respectively. Therefore, the biosynthesis of canthaxanthin using microbial cell factories is becoming an advantageous alternative. Furthermore, microbial synthesis represents an economic and sustainable approach as it enables the use of agriculture and industrial wastes as substrates. In this work, the extraction, recovery and purification of canthaxanthin from modified yeasts using food grade solvents and up-scalable methodologies was studied. The resulting canthaxanthin-enriched extract was characterized (UV-Vis, PXRD and SEM) and quantified (HPLC), resulting in a canthaxanthin purity of 43.7 % (w/w).
- Comparative analysis of mannans extraction processes from spent yeast saccharomyces cerevisiaePublication . Faustino, Margarida; Durão, Joana; Pereira, Carla F.; Oliveira, Ana Sofia; Pereira, Joana Odila; Pereira, Ana M.; Ferreira, Carlos; Pintado, Manuela E.; Carvalho, Ana P.Mannans are outstanding polysaccharides that have gained exponential interest over the years. These polysaccharides may be extracted from the cell wall of Saccharomyces cerevisiae, and recovered from the brewing or synthetic biology industries, among others. In this work, several extraction processes—physical, chemical and enzymatic—were studied, all aiming to obtain mannans from spent yeast S. cerevisiae. Their performance was evaluated in terms of yield, mannose content and cost. The resultant extracts were characterized in terms of their structure (FT-IR, PXRD and SEM), physicochemical properties (color, molecular weight distribution, sugars, protein, ash and water content) and thermal stability (DSC). The biological properties were assessed through the screening of prebiotic activity in Lactobacillus plantarum and Bifidobacterium animalis. The highest yield (58.82%) was achieved by using an alkaline thermal process, though the correspondent mannose content was low. The extract obtained by autolysis followed by a hydrothermal step resulted in the highest mannose content (59.19%). On the other hand, the extract obtained through the enzymatic hydrolysis displayed the highest prebiotic activity. This comparative study is expected to lay the scientific foundation for the obtention of well-characterized mannans from yeast, which will pave the way for their application in various fields.
- Effect of drying technology in Saccharomyces cerevisiae mannans: structural, physicochemical, and functional propertiesPublication . Faustino, Margarida; Pereira, Carla F.; Durão, Joana; Oliveira, Ana Sofia; Pereira, Joana Odila; Ferreira, Carlos; Pintado, Manuela E.; Carvalho, Ana P.Mannans are polysaccharides whose physicochemical and biological properties render them commercialization in several products. Since these properties are strongly dependent on production conditions, the present study aims to assess the impact of different drying technologies – freeze (FDM) and spray drying (SDM) – on the structural, physicochemical, and biological properties of mannans from Saccharomyces cerevisiae. Structural analysis was assessed by FT-IR, PXRD and SEM, whereas physicochemical properties were evaluated based on sugars, protein, ash and water contents, solubility, and molecular weight distribution. Thermal behaviour was analysed by DSC, and antioxidant activity by DPPH and ABTS assays. The parameters which revealed major differences, in terms of structural and physicochemical properties regarded morphology (SEM), physical appearance (colour), moisture (3.6 ± 0.1 % and 11.9 ± 0.6% for FDM and SDM, respectively) and solubility (1 mg/mL for FDM and 25 mg/mL for SDM). Nevertheless, these differences were not translated into the antioxidant capacity.
- Effect of mannan oligosaccharides extracts in uropathogenic escherichia coli adhesion in human bladder cellsPublication . Faustino, Margarida; Silva, Sara; Costa, Eduardo M.; Pereira, Ana Margarida; Pereira, Joana Odila; Oliveira, Ana Sofia; Ferreira, Carlos M. H.; Pereira, Carla F.; Durão, Joana; Pintado, Manuela E.; Carvalho, Ana P.Urinary tract infections (UTIs) are a common public health problem, mainly caused by uropathogenic Escherichia coli (UPEC). Patients with chronic UTIs are usually treated with long-acting prophylactic antibiotics, which promotes the development of antibiotic-resistant UPEC strains and may complicate their long-term management. D-mannose and extracts rich in D-mannose such as mannan oligosaccharides (MOS; D-mannose oligomers) are promising alternatives to antibiotic prophylaxis due to their ability to inhibit bacterial adhesion to urothelial cells and, therefore, infection. This highlights the therapeutic potential and commercial value of using them as health supplements. Studies on the effect of MOS in UTIs are, however, scarce. Aiming to evaluate the potential benefits of using MOS extracts in UTIs prophylaxis, their ability to inhibit the adhesion of UPEC to urothelial cells and its mechanism of action were assessed. Additionally, the expression levels of the pro-inflammatory marker interleukin 6 (IL-6) were also evaluated. After characterizing their cytotoxic profiles, the preliminary results indicated that MOS extracts have potential to be used for the handling of UTIs and demonstrated that the mechanism through which they inhibit bacterial adhesion is through the competitive inhibition of FimH adhesins through the action of mannose, validated by a bacterial growth impact assessment.
- Efficient ammonium removal from marine aquaculture wastewater with microalgal-bacterial granular sludge technologyPublication . Alves, Marta; Oliveira, Ana Sofia; Castro, Paula Maria Lima; Amorim, Catarina LeiteWater recirculation in marine aquaculture is fundamental for the protection of water resources and for the sector sustainability as it enables to reduce water usage 1. Microalgal-bacterial granular sludge (MBGS) has the potential to increase the removal efficiency of pollutants from wastewaters benefiting from the diverse metabolism allowing water recirculation. Moreover, MBGS would allow costs reduction both in biomass separation from the treated water given the rapid settling properties and in aeration due to microalgae oxygen production 2.This study aimed to develop MBGS able to treat marine aquaculture effluents. For that, a lab-scale photo sequencing batch reactor was inoculated with activated sludge, previously adapted to salty wastewater, and a microalgae consortium enriched from water collected at a marine aquaculture. Feeding composition was established to simulate marine aquaculture streams. The aggregation of microalgal and bacterial biomass to form granular structures occurred rapidly. Throughout the operation, dark green granules with a dense and compact structure became predominant together with an increase in chlorophyll and carotenoids content in biomass. Ammonia was absent from the reactor effluent, but the nitrite levels were often above the toxicity levels for fish. Nevertheless, the dissolved oxygen concentration in the treated water was high (> 8.63 mg/L). The microalgal-bacterial granules proved to be efficient in producing streams with high dissolved oxygen levels, lowering the needed of water oxygenation before reuse and without ammonium ions. However, for water recirculation, improvement of the nitrite removal is needed to maintain the levels below the fish toxicity levels.
- Iron-peptide complexes from spent yeast: evaluation of iron absorption using a Caco-2 monolayerPublication . Oliveira, Ana Sofia; Ferreira, Carlos M. H.; Pereira, Joana Odila; Silva, Sara; Costa, Eduardo M.; Pereira, Ana Margarida; Faustino, Margarida; Durão, Joana; Pintado, Manuela E.; Carvalho, Ana P.Anaemia is one of the most prevalent nutritional diseases worldwide with Fe deficiency being its major cause. In fact, the limited bioavailability of dietary iron and its interaction with food compounds contribute to its poor absorption in the human body and dietary Fe supplementation has been widely used to address this issue. By incorporating a circular economy framework, this study takes a novel approach of production of iron-peptide complexes from spent yeast peptide-rich extracts as a more effective substitute to conventional salt-based iron supplements, which are related with adverse consequences. Considering the regulation of iron absorption on duodenal enterocytes, iron-peptides complexes absorption was assessed using a Caco-2 monolayer, evaluating both iron uptake and the capacity to stimulate ferritin synthesis, after their in vitro simulated gastrointestinal digestion following INFOGEST protocol. An iron salt and a commercially available benchmark (iron bisglycinate) were also included in this study to compare the absorption performance. Results showed that iron-peptide complexes exhibited a similar behaviour (no statistically significant alterations (p > 0.05)) concerning the other tested samples, thus being a promising alternative for iron dietary supplementation. The remaining digested peptides from the complexes also showed potential antioxidant activity, suggesting protection of iron from oxidation within human body.
- Peptide extract from spent yeast improves resistance of Saccharomyces cerevisiae to oxidative stressPublication . Lopes, Ana; Azevedo-Silva, João; Carsanba, Erdem; Pintado, Manuela; Oliveira, Ana Sofia; Ferreira, Carlos; Pereira, Joana Odila; Carvalho, Ana P.; Oliveira, CarlaYeast cells face various stress factors during industrial fermentations, since they are exposed to harsh environmental conditions, which may impair biomolecules productivity and yield. In this work, the use of an antioxidant peptide extract obtained from industrial spent yeast was explored as supplement for Saccharomyces cerevisiae fermentation to prevent a common bottleneck: oxidative stress. For that, a recombinant yeast strain, producer of β-farnesene, was firstly incubated with 0.5 and 0.7 g/L peptide extract, in the presence and absence of hydrogen peroxide (an oxidative stress inducer), for 1–5 h, and then assayed for intracellular reactive oxygen species, and growth ability in agar spot assays. Results showed that under 2 mM H2O2, the peptide extract could improve cells growth and reduce reactive oxygen species production. Therefore, this antioxidant effect was further evaluated in shake-flasks and 2-L bioreactor batch fermentations. Peptide extract (0.7 g/L) was able to increase yeast resistance to the oxidative stress promoted by 2 mM H2O2, by reducing reactive oxygen species levels between 1.2- and 1.7-fold in bioreactor and between 1.2- and 3-fold in shake-flask fermentations. Moreover, improvements on yeast cell density of up to 1.5-fold and 2-fold, and on biomolecule concentration of up to 1.6-fold and 2.8-fold, in bioreactor and shake-flasks, respectively, were obtained. Thus, culture medium supplementation with antioxidant peptide extracted from industrial spent yeast is a promising strategy to improve fermentation performance while valuing biomass waste. This valorization can promote a sustainable and eco-friendly solution for the biotechnology industry by the implementation of a circular economy model.
- Peptide-rich extracts from spent yeast as potential microbiota modulatorsPublication . Oliveira, Ana Sofia; Carvalho, Nelson Mota de; Ferreira, Carlos; Pereira, Joana Odila; Pintado, Manuela; Madureira, Ana Raquel; Carvalho, Ana P.
- Production of iron-peptide complexes from spent yeast for nutraceutical industryPublication . Oliveira, Ana Sofia; Ferreira, Carlos M. H.; Pereira, Joana Odila; Sousa, Sérgio; Faustino, Margarida; Durão, Joana; Pereira, Ana Margarida; Pintado, Manuela E.; Carvalho, Ana P.Iron (Fe) deficiencies are a major health condition concern and over the years many solutions in the form of Fe supplementation have been investigated. Organic Fe-complexes are the most promising for Fe deficiencies remediation. The aim of present study was to value peptide rich waste streams from β-glucan and mannan production from spent yeast (Gpep and Mpep, respectively) as Fe-peptide complexes for Fe supplementation. These waste streams were first subjected to ultrafiltration treatment before assessing the capacity of these fractions to complex Fe was evaluated, without, and with nitrogen. Results have shown that Gpep> 1 kDa was the best fraction with a optimal pH of 6.0 and a time of 30 min. The resulting Fe-peptide complex was characterized using powder XDR, fluorescence, FTIR, SEM and Mastersizer Laser Diffraction. Results have shown that Gpep and Mpep waste streams have potential application as Fe supplementation in the form of Fe peptide complexes.
- Purification of bioactive peptides from spent yeast autolysatesPublication . Oliveira, Ana Sofia; Pereira, Ana Margarida; Ferreira, Carlos M.H.; Pereira, Joana Odila; Amorim, Manuela; Faustino, Margarida; Durão, Joana; Pintado, Manuela E.; Carvalho, Ana P.Spent brewer’s yeast have been described as an important source for bioactive peptides, with their properties well proven over the years. Besides the brewing sector, growing of large-scale processes on synthetic biology industry has generated a substantial amount of spent engineered yeast with further potential to be valued in a circular economy approach. In line with this perception, in this work, peptide-rich fractions were obtained from spent yeast peptide-rich extract autolysate (“ESY1”), using two different techniques, namely protein ultrafiltration and size-exclusion chromatography (SEC). Both methods allowed the production of different peptide fractions with diverse protein content, molecular weight distribution and peptides sequences. Overall, fractions with higher protein content and more purified reveal higher bioactivities, namely antihypertensive and anticholesterolemic, emphasizing that the purification process is an important step to include in production process of a dietary supplement with these specific features. In addition, significant antioxidant capacity values for peptide fractions purified by SEC were obtained, highlighting their potential use in economic sectors where antioxidant capacity has a massive impact, such as cosmetics.