Browsing by Author "Areal-Hermida, Lara"
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- Antimicrobial activity of food-isolated fungi extractsPublication . Ferreira, Diogo; Areal-Hermida, Lara; Baylina, Pilar; Fernandes, Rúben; Sieiro, CarmenOne major source for drug discovery are microbial metabolites. Fungi, renowned for their ability to produce an array of broad and diverse secondary metabolites, due to their extensive dispersion and diversity, offer a rich resource for drug discovery. Antibiotic resistance is a major concern. Rapid increase of resistant bacteria worldwide, dampens antibiotic efficiency, burdens healthcare services and increase morbidity and mortality. Antibiotic misuse and lack of new drug development are the main responsible for this health crisis. So, the creation of fungal libraries to find and study new compounds is essential to tackle the rising of antimicrobial resistance and continue with industrial efforts of drug discovery and production. Isolation from chestnuts, chestnut flour and sunflower seeds allowed us to obtain a collection of 165 fungal isolates. Bioactivity of fungal extracts were screened against different antibiotic resistant bacteria. Bacteria grown overnight, adjusted to 1.5 x 108 CFU/mL was exposed to fungal extracts, at a concentration of 100 μg/mL for 24 hours and inhibition rates were calculated. Several extracts showed activity against antimicrobial resistant bacteria and further studies should be made in order to find if new molecules could be responsible for our fungi antimicrobial activity.
- Evaluation of the probiotic potential of a strain of Saccharomyces cerevisiaePublication . Areal-Hermida, Lara; Pichardo-Gallardo, Ángeles; Coelho, Pedro; Prudêncio, Cristina; Sieiro, CarmenAccording to the World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO), probiotics are living microorganisms that, when administered in appropriate quantities, can confer a beneficial effect on the health of the host. Probiotic potential has been demonstrated especially for many strains of different species of bacteria. However, there are fewer strains of yeast for which their probiotic properties have been studied, despite their advantages, which include the fact that they are not affected by antibacterial antibiotics or their inability to disperse antibiotic resistance genes. As a result, there is a growing interest in characterizing new yeasts as probiotics. The aim of this study was to evaluate in our laboratories the probiotic potential of a strain of Saccharomyces cerevisiae var. boulardii (the main species marketed as a probiotic so far), to compare it with that of other yeasts. Strain identification was carried out by analyzing the ITS and D1/D2 regions of the rDNA. Regarding the ability of the strain to survive at 37ºC and resist gastrointestinal conditions, the strain showed 100 % viability at 37ºC and between 95-100 % in synthetic gastric and duodenal juices (pH 2-7.5, 0.3-10 % bile salts, 0.3 % pepsin and 0.1 % pancreatin). In addition, the selfaggregation and hydrophobicity properties shown by the strain allowed inferring the ability to adhere to the intestine, which was confirmed in Caco-2 cells. Additionally, the strain presented other properties of interest for probiotics, including a high anti-oxidant capacity and pathogen coaggregation, as well as a variable cytotoxic activity against different tumor cell lines.
- Potential probiotic and functional properties of Brettanomyces strains isolated from kombucha teaPublication . Areal-Hermida, Lara; Coelho, Pedro; Pichardo-Gallardo, Ángeles; Prudêncio, Cristina; Sieiro, CarmenKombucha, a beverage traditionally obtained through the fermentation of tea, is believed to have beneficial health properties. Therefore, characterizing the microorganisms responsible for this fermentation is essential to demonstrate its potential health benefits and to identify candidates for new probiotics. In this study, four probiotic yeast strains isolated from kombucha tea were identified, by the PCR-RFLP analysis of the ribosomal ITS region and the sequence of the D1/D2 domain of the 26S rDNA, as Brettanomyces bruxellensis (UVI55 and UVI56) and B. anomalus (UVI57 and UVI58). Properties relevant to probiotics were also studied in these strains. All of them showed excellent survival in simulated gastric (99%–100%) and duodenal (95%–100%) juices. The ability to self-aggregate (38%–100%), adhesion to xylene (15%–50%) and, above all, adhesion to Caco-2 cells (4%–21%), revealed its potential capacity to adhere to the intestinal epithelium. In addition, the tested strains showed excellent antioxidant capacity (82%–94%), antimicrobial activity against different pathogens (Escherichia coli, Staphylococcus aureus, Salmonella enterica, Listeria monocytogenes, and Bacillus cereus), as well as remarkable cytotoxic activity against colon, melanoma and ovarian tumor cell lines. Finally, using Caenorhabditis elegans as a model, strain UVI56 exhibited ability to both extend the lifespan of the nematode and protect it against infection by S. enterica. These results support the probiotic and functional properties of the analyzed strains. In conclusion, the study revealed that kombucha tea could be a source of potential probiotics that contribute to its health-promoting properties and that the characterized Brettanomyces strains could be exploited directly as probiotics or for the development of new functional foods.