Search results for "ACID BACTERIA"
showing 10 items of 165 documents
Microbiological characteristics of traditional Caciocavallo Palermitano cheese making
2011
Potential of an Exploitation of Acid-Tolerant Antimicrobial Microorganisms Evolving Enzyme Systems for the Utilization of Dairy By-products and Ligno…
2016
Development of an ad hoc starter culture for the production of functional raw ewes’ milk cheeses through the addition of grape pomace powder
2019
The present work was carried out to select lactic acid bacteria (LAB) resistant to polyphenols in order to develop an ad hoc starter culture for the production of functional fresh ewes’ milk cheeses through the addition of grape pomace powder (GPP). To this purpose, raw ewes’ milk samples were inoculated with individual polyphenols belonging to five classes: flavanols (cathechin, epicatechin and epigallocathechin), flavonols (quercetin), flavones (rutin), hydroxyl-benzoic acid (vanillic acid and syringic acid) and hydroxyl-cinnamic acid (caffeic acid and cumaric acid). These polyphenols are commonly associated with the wine industry by-products and were added in milk to a final concentratio…
Different Modes of Regulation of the Expression of Dextransucrase in
2019
Leuconostoc lactis AV1 strain isolated from a Tunisian avocado was characterized as a dextran producer. The promoter PdsrLL and the dsrLL gene encoding the DsrLL dextransucrase responsible for the dextran synthesis were transcriptionally fused to the mCherry coding gene generating the pRCR20 plasmid. Upon plasmid transfer, both AV1n and the dextran non-producing Leuconostoc mesenteroides CM70 became red due to expression of the mCherry from the PdsrLL-dsr-mrfp transcriptional fusion. Characterization of the polymers present in cultures supernatants revealed that the DsrLL encoded from pRCR20 in the recombinant bacteria was able to synthesize dextran. The production of dextran by the DsrLL i…
Estudio de la reducción química y biológica de hongos y micotoxinas en pan
2017
El deterioro de los alimentos causado por los hongos que producen micotoxinas representa un problema importante en seguridad alimentaria. Los cereales en grano y sus productos derivados, como el pan, frecuentemente están contaminados con hongos micotoxigénicos. Es por ello que en la presente Tesis Doctoral se han estudiado la presencia de 17 micotoxinas en 80 muestras de pan de molde y el riesgo de exposición de la población a estos compuestos. Aflatoxinas (AFs), zearalenona (ZEA) y eniatinas (ENs) han sido detectadas respectivamente en el 20%, 65% y 96% de las muestras de pan analizadas. La presencia de dichas micotoxinas y, sobre todo, de las muestras en las que las AFs y la ZEA superan e…
Dextransucrase Expression Is Concomitant with that of Replication and Maintenance Functions of the pMN1 Plasmid in
2017
The exopolysaccharide synthesized by Lactobacillus sakei MN1 is a dextran with antiviral and immunomodulatory properties of potential utility in aquaculture. In this work we have investigated the genetic basis of dextran production by this bacterium. Southern blot hybridization experiments demonstrated the plasmidic location of the dsrLS gene, which encodes the dextransucrase involved in dextran synthesis. DNA sequencing of the 11,126 kbp plasmid (pMN1) revealed that it belongs to a family which replicates by the theta mechanism, whose prototype is pUCL287. The plasmid comprises the origin of replication, repA, repB, and dsrLS genes, as well as seven open reading frames of uncharacterized f…
Development of molecular approaches for direct detection and quantification of wine-related microorganisms
2018
En esta tesis doctoral se han desarrollado procedimientos para la detección y cuantificación de levaduras y bacterias acéticas totales y, en concreto, de las especies más importantes en la vinificación como Saccharomyces cerevisiae, Brettanomyces bruxellensis, Zygosaccharomyces bailii, L. plantarum, y O. oeni. Las estrategias que se han utilizado para el desarrollo de nuevos métodos se centran fundamentalmente en la supresión del paso de extracción previa de ADN y de los procedimientos de eliminación de inhibidores de la reacción de PCR presentes en las muestras. Para llevar a cabo este objetivo general, se establecieron los siguientes objetivos específicos; 1, desarrollo de un método de qP…
Sourdough and cereal-based foods: traditional and innovative products
2017
Cereals represent the main crop of the five continents and contribute greatly to the diet of several populations. Cereals often undergo a fermentation before eating. This process is fundamental to confer high sensory quality, as well as to preserve and enhance the nutritional and safety aspects of the resulting products. Fermented cereal based foods are complex microbial ecosystems, mainly represented by lactic acid bacteria and yeasts. Among these products, sourdough is worldwide applied to produce breads. Sourdough technology is also used to improve the final characteristics of fortified and gluten–free breads. This chapter focuses on the use of cereals to produce the most relevant fermen…
Development of an ad hoc natural whey starter culture for the production of Vastedda della valle del Belìce cheese
2013
This work was aimed to characterize the autochthonous lactic acid bacteria (LAB) of PDO Vastedda della valle del Belìce cheeses, produced in several dairy factories, for the development of an ad hoc starter culture preparation for the production of this cheese. To this purpose, winter and spring productions were analysed, in order to isolate LAB adapted to perform the fermentation at low temperatures. Plate counts showed the total microbial counts (TMC) till levels of 9 -1almost 10 CFU g and all cheese samples were dominated by coccus LAB. Not all samples were positive for the presence of enterobacteria, but when they were found their concentrations were at similar levels in both seasons. A…
Utilizzo del pied de cuve fortificato per la fermentazione spontanea di vini rossi di qualità
2018
La fermentazione spontanea è un processo biologico incontrollato durante il quale molti lieviti e/o batteri potrebbero aumentare rapidamente in concentrazioni tali incidere negativamente sulla qualità del prodotto finale. A tal proposito, al fine di ottimizzare la crescita di lieviti con buone attitudini enologiche, si utilizza il metodo “pied de cuve”. Questa tecnica enologica è in grado di realizzare in una determinata massa di mosto dal volume ridotto, una fermentazione alcolica con un ceppo di lievito opportunamente inoculato o con ceppi di lieviti indigeni, naturalmente presenti nel mosto. Al fine di valorizzazione ed aumentare la diffusione di pratiche enologiche basate su un ridotto …