3,718 research outputs found
Cultivos lácteos funcionales: origen y aplicaciones
No full textTrabajo presentado en el VI Congreso Nacional de Microbiología Industrial y Biotecnología Microbiana (CMIBM), celebrado en León (España) del 12 al 14 de septiembre de 2016Las bacterias ácido-lácticas (BAL) son los componentes más habituales de los cultivos iniciadores utilizados en la fermentación de la leche. Las más típicas se agrupan en los géneros Lactococcus, Lactobacillus, Leuconostoc y Pediococcus. Junto a las BAL ocasionalmente se agrupan también a especies de géneros como Propionibacterium y Bifidobacterium por encontrarse en los mismos hábitats o por utilizarse con los mismos propósitos.
Microbiología de quesos tradicionales y selección de fermentos
Las bacterias de estos tipos aparecen asociadas a la leche, la carne y materiales vegetales y son responsables de su fermentación. De forma ancestral, las fermentaciones se llevaban a cabo por microorganismos adventicios presentes en la materia prima o procedentes del entorno de elaboración. Por motivos de higiene y para homogenizar las características sensoriales, la contaminación accidental se ha ido sustituyendo por la utilización de cultivos iniciadores o fermentos. Estos se definen como ¿una o más cepas de una o más especies microbianas que se inoculan en una materia prima para iniciar su fermentación¿. Los fermentos promueven la acidificación de forma eficiente y participan en los cambios que tienen lugar durante la maduración modificando la textura, el aroma y el sabor. Dadas sus funciones, resulta esencial la identificación de las cepas más apropiadas para reproducir las fermentaciones tradicionales o para emprender otras nuevas. De manera aplicada, el término fermento engloba a todos los microorganismos que se añaden los alimentos con una intención tecnológica.
Microbiología intestinal humana y selección de probióticos
BAL y bifidobacterias forman parte también de la microbiota del tracto gastrointestinal de los animales y del hombre, donde parecen contribuir a mantener el equilibrio microbiano necesario en el estado de salud: antagonizan a los patógenos, mejoran la digestibilidad de compuestos de la dieta y actúan como coadyuvantes inmunológicos. Por estos motivos, varias cepas se utilizan como probióticos (¿microorganismos vivos que ingeridos en cantidades adecuadas mejoran la salud del consumidor¿). Aunque no hay un criterio único, existe un consenso sobre las características deseables que deben poseer los microorganismos probióticos, así como otras de las que deben carecer. Las cepas probióticas han de responder también a las necesidades de los procesos industriales. La identificación y selección de probióticos es un proceso largo y complejo en el que hay que ir descartando las cepas que no cumplan los criterios de probiosis, seguridad y tecnológicos establecidos a priori.Peer reviewe
¿Qué debemos hacer?. Desde la administración hasta el consumidor
No full textTrabajo presentado en el II Congreso de Quesos Ibéricos con DOP, celebrado en Cangas de Onís (Asturias) los días 15 y 16 de octubre de 2016Peer reviewe
Critical pedagogy in hard financial times
No full textPeter Mayo takes issue with education financing not from an economic or technical
viewpoint, but from a philosophical and systemic one, drawing on critical pedagogy.
There is no sense, this article argues, to talk of higher education or its funding without
reference to the capitalist system which the mainstream education discourse reaffirms. The author concludes with an alternative vision of lifelong learning as a social act for the creation and enhancing of democratic spaces, reflected in the ongoing global “Occupy” protests for social equality.peer-reviewe
Monitoring tetracycline resistance in cheese by functional metagenomics
No full textTrabajo presentado en el 7th Congress of European Microbiologists (FEMS 2017), celebrado en Valencia (España), del 9 al 13 de julio de 2017Antibiotic resistance (AR) in bacteria -a consequence of the use, misuse and overuse of antibiotics (Woolhouse et al., 2006)- is currently the major problem worldwide for human health. Overtime, the study of antibiotic resistance has grown from focusing on pathogenic and opportunistic microorganisms (Fair and Tor, 2014) and less attention has been paid to antibiotic resistance in commensal and beneficial bacteria (Broaders et al., 2013). The prevalence of antibiotic resistant bacteria in a broad range of foods has led to a growing concern
about the impact that food (and hence food-borne bacteria) may have as reservoirs of antibiotic resistance genes (Marshall and Levy, 2011). Therefore, the complex microbial interactions taking place during the manufacture of fermented foods, and the following contact of these microorganisms with the microbial populations of the human gut, provide ideal scenarios for horizontal gene transfer. Recent years have seen the characterization of resistance determinants in a number of antibiotic-resistant bacteria isolated from dairy
products (Flórez and Mayo, 2015; Devirgiliis et al., 2010), however, the dairy “resistome”, all the antibiotic resistance determinants present in dairy products, is far from fully known. Metagenomic techniques and massive sequencing have been successfully used to monitor antibiotic resistance genes in environmental, animal and human ecosystems. However, despite the claim that the food chain plays a key role in the spread of antibiotic resistance, metagenomic analysis has scarcely been used to investigate food systems. These techniques allow for the molecular characterization of the resistance genes and their associated genetic elements; this may further help to estimate the risk for their horizontal transference.Peer reviewe
Soy and soy products, isoflavones, equol, and health
No full textIn Asian countries, soybeans have been used as food and food ingredients for centuries and their consumption have been associated with beneficial health effects. In addition to their nutritive value, soybeans
have many active chemical compounds, among which isoflavones are the most important. Isoflavones
are plant-derived phytoestrogens, chemically comparable in their structure and properties to human
estrogens. For isoflavones to become bioavailable, their activation and/or conversion into more active
metabolites, such equol from daidzein, must occur. Equol is the isoflavone metabolite with the greatest
estrogenic activity and antioxidant capacity. Epidemiological studies have suggested that high intakes
of isoflavones reduce the symptoms of menopause as well as the incidence of hormone-dependent and
aging-associated diseases such as osteoporosis, cardiovascular disease and cancer. This chapter reviews
soy consumption, isoflavone metabolism, and briefly summarizes the results of recent clinical trials on,
and meta-analyses of, the effects of isoflavone consumption on human health.Peer reviewe
Presentation_3_Genome Analysis of Lactobacillus plantarum LL441 and Genetic Characterisation of the Locus for the Lantibiotic Plantaricin C.PPTX
No full textBacteriocins are ribosomally synthesized peptides produced by bacteria with antimicrobial activity. The bacteriocins produced by lactic acid bacteria (LAB) may inhibit food-borne pathogens and spoilage organisms, and therefore have potential as natural preservatives. Lactobacillus plantarum LL441 produces a lantibiotic bacteriocin known as plantaricin C, a pore-forming antimicrobial peptide containing modified amino acids that inhibits cell wall synthesis by forming a complex with the peptidoglycan precursor lipid II. The present work describes the genome sequencing of L. plantarum LL441 and the characterisation of the plantaricin C locus. The draft genome sequence of L. plantarum LL441 consisted of 170 contigs and had a total 3,124,603 bp; the GC content was 44.52%. The plantaricin C locus was found in an 18 kbp-long contig, and consisted of six genes organized in an operon-like arrangement. This locus included the bacteriocin structural gene (plnC), followed by a gene encoding a LanM-like protein thought to be involved in the maturation of plantaricin C, and four downstream genes encoding ABC-type transporter components, probably belonging to its putative immunity and export machinery. plnC encodes a precursor of the bacteriocin, i.e., a 58-amino acid peptide containing a 31-amino acid double-glycine leader peptide and a 27-amino acid core peptide. In silico analysis and hybridisation experiments placed the plantaricin C locus to be located on pLL441-1, a large plasmid of L. plantarum LL441. Joining up the gaps between the contigs by conventional PCR, sequencing of the amplicons, and sequence assemblage, allowed the complete 55.3 kbp pLL441-1 molecule to be established. A portion of pLL441-1 larger than 34 kbp, which included the plantaricin C region, was identified in a plasmid-derived contig from the L. plantarum Nizo 3893 genome. Further, the plantaricin C coding locus (about 8.7 kbp) was shown to share 91% nucleotide identity with a portion of the plasmids pPECL-6 from Pediococcus claussenii ATCC BAA-344 and pL11995-4 from Lactobacillus paracollinoides TMW 1.1995. Knowledge of the sequence of the plantaricin C coding region will help in studying its molecular components and allow their involvement in bacteriocin synthesis to be investigated, facilitating the use of the bacteriocin or its genetic elements in new biotechnological applications.</p
Antibiotic resistance in non-starter, wild strains of Streptococcus thermophilus, and molecular and genomic analysis of atypical resistances
No full textTrabajo presentado en el 12th International Symposium on Lactic Acid Bacteria, celebrado en Egmond aan Zee (Holanda) del 27 al 31 de agosto de 2017Resistance to antibiotics in food-borne commensal and beneficial microorganisms is not of clinical concern. However, resistant populations could serve as reservoirs of resistance determinants, which could ultimately be transferred during food manufacture or food consumption to pathogens (Rossi et al., 2014). Streptococcus thermophilus is a thermophilic lactic acid bacteria (LAB) species of great industrial use; the second in economic importance after Lactococcus lactis (Parente and Cogan, 2004). S. thermophilus is used as a starter in the production of yoghurt along with Lactobacillus delbrueckii subsp. bulgaricus. In combination with other lactobacilli species, it is also used in the manufacture of Swiss (Emmenthal, Gruyère) and Italian (Grana, Parmesan, Provolone, Mozzarella, etc.) cheese varieties. Its use has recently been extended to cheeses made with mesophilic starters such as Cheddar, Gouda, Manchego and others. Although S. thermophilus has never been found among the microbiota components of traditional Spanish cheeses, our group has detected the presence of DNA from S. thermophilus in several cheese types using culture-independent microbial techniques. Detection of DNA remains of this species has allowed the development of selective enrichment strategies for isolation of S. thermophilus strains from raw milk and raw milk-made cheeses. In this communication we report on the resistance/susceptibility profiles of 41 S. thermophilus wild isolates to a set of antibiotics from different classes together with the characterization of the genetic basis of atypical resistancesPeer reviewe
Characterization of glycosyl-hydrolases acting on isoflavones from Bifidobacterium pseudocatenulatum IPLA 36007
No full textTrabajo presentado en el 1er Congreso Iberoamericano de Biotecnología: "Bio.Iberoamérica 2016. Biotecnología Integrando Continentes”, celebrado en Salamanca (España) entre el 5 y el 8 de junio de 2016.Glycosidases (glycosyl hydrolases) are a wide and varied group of enzymes able to hydrolyse the glycosidic linkage between two or more sugars or one sugar and a chemical residue of other nature. Bifidobacteria species are currently being used as probiotics for the maintenance of a healthy status. Bifidobacteria have their natural niche in the human and animal gastrointestinal tracts. Glycolytic activities of probiotic bifidobacteria are thought to have a prominent role for these bacteria to colonize and survive in the intestinal ecosystem. Additionally, these enzymatic activities might contribute to their probiotic functionality.
Objectives
Bifidobacterium pseudocatenulatum IPLA 36007 is a strain from human origin showing deglycosylation activity on isoflavone-glycosides, an essential step for isoflavones to become bioavailable and the subsequent formation of more active compounds such as equol. The genome of IPLA 36007 has recently been sequenced (Alegría et al., 2014) allowing to investigate its genetic potential. Genome analysis showed a vast array of genes encoding glycosyl hydrolases, of which some were tentatively classified as ß-glucosidases. This study aimed to identify and characterize ß-glucosidases from IPLA 36007 acting on isoflavone-glycosides.
Results and Discussion
Five genes encoding putative ß-glucosidases (Glu-1 through Glu-5) were synthetized under the control of a heterologous promoter working on bifidobacteria and cloned in a pUC19-derived vector. Expression in Escherichia coli proved that four of the genes encode glycosidases, of which three were considered ß-glucosidases (Glu-1, Glu-2 and Glu-4) and one an ¿-glucosidase (Glu-3). The three ß-glucosidases showed activity towards the isoflavone glycoside daidzin producing daidzein. Activity of Glu-4 was shown to be 6- to 10-fold higher than that of Glu-1 and Glu-2, respectively. The genetic determinants were subsequently transferred to pET28a(+), a His-Tag vector designed for convenient cloning and expression of genes, and purification of the corresponding proteins. Recombinant enzymes were purified by immobilized metal affinity chromatography and characterized. The main biochemical properties of the two ß-glucosidases will be presented in the poster.Peer reviewe
Isoflavonas y equol: mito o realidad
No full textTrabajo presentado en el XI Congreso Internacional de Fitoterapia Ciudad de Oviedo: Panorama actual de la Fitoterapia, celebrado en Oviedo (Asturias, España) del 13 al 15 de abril de 2018Diversos estudios epidemiológicos sugieren que la ingesta de soja reduce el riesgo de padecer enfermedades y síndromes mediados por hormonas entre los que cabe destacar los síntomas de la menopausia, varias enfermedades cardiovasculares y neurodegenerativas y algunos tipos tipo de cáncer. Los efectos beneficiosos de la soja se atribuyen a su contenido en proteínas de gran valor biológico y a su alta concentración en isoflavonas. Las isoflavonas son polifenoles con actividad estrogénica debido a su similitud estructural con el 17ß-estradiol. En la planta, las isoflavonas se encuentran en forma de glucósidos conjugadas con azúcares; estos necesitan escindirse para que sean biodisponibles para el organismo. El proceso de desconjugación lo realizan enzimas tisulares y otros de la microbiota intestinal. Las agliconas se metabolizan posteriormente en el intestino dando lugar a compuestos con mayor actividad biológica (como el equol a partir de daidzeína) o inactivos como la o-dimetilangolensina (O-DMA). Mientras que un 90% de la población es capaz de producir O-DMA, tan solo un 25-35% de los individuos producen equol; estos podrían ser los únicos que se benefician del consumo de isoflavonas. En contraste con los datos epidemiológicos, los efectos beneficiosos de las isoflavonas en los estudios de intervención no son tan concluyentes. Entre otras casusas, las inconsistencias pueden deberse a variaciones interindividuales en la microbiota. Poco se conoce de las rutas y los microbios involucrados en el metabolismo de las isoflavonas y en la producción de equol. Este conocimiento resulta indispensable para maximizar la formación de los compuestos más saludables y extender sus efectos a la población general.Peer reviewe
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