1,721,340 research outputs found
Comparison of statistical methods for identification of Streptococcus thermophilus, Enterococcus faecalis, and Enterococcus faecium from Randomly Amplified Polymorphic DNA Patterns.
No full textThermophilic streptococci play an important role in the manufacture of many European cheeses, and a rapid and reliable method for their identification is needed. Randomly amplified polymorphic DNA (RAPD) PCR (RAPD-PCR) with two different primers coupled to hierarchical cluster analysis has proven to be a powerful tool for the classification and typing of Streptococcus thermophilus, Enterococcus faecium, and Enterococcus faecalis (G. Moschetti, G. Blaiotta, M. Aponte, P. Catzeddu, F. Villani, P. Deiana, and S. Coppola, J. Appl. Microbiol. 85:25–36, 1998). In order to develop a fast and inexpensive method for the identification of thermophilic streptococci, RAPD-PCR patterns were generated with a single primer (XD9), and the results were analyzed using artificial neural networks (Multilayer Perceptron, Radial Basis Function network, and Bayesian network) and multivariate statistical techniques (cluster analysis, linear discriminant analysis, and classification trees). Cluster analysis allowed the identification of S. thermophilus but not of enterococci. A Bayesian network proved to be more effective than a Multilayer Perceptron or a Radial Basis Function network for the identification of S. thermophilus, E. faecium, and E. faecalis using simplified RAPD-PCR patterns (obtained by summing the bands in selected areas of the patterns). The Bayesian network also significantly outperformed two multivariate statistical techniques (linear discriminant analysis and classification trees) and proved to be less sensitive to the size of the training set and more robust in the response to patterns belonging to unknown species
Comparison of statistical methods for identification of Streptococcus thermophilus, Enterococcus faecalis, and Enterococcus faecium from Randomly Amplified Polymorphic DNA Patterns.
No full textThermophilic streptococci play an important role in the manufacture of many European cheeses, and a rapid and reliable method for their identification is needed. Randomly amplified polymorphic DNA (RAPD) PCR (RAPD-PCR) with two different primers coupled to hierarchical cluster analysis has proven to be a powerful tool for the classification and typing of Streptococcus thermophilus, Enterococcus faecium, and Enterococcus faecalis (G. Moschetti, G. Blaiotta, M. Aponte, P. Catzeddu, F. Villani, P. Deiana, and S. Coppola, J. Appl. Microbiol. 85:25–36, 1998). In order to develop a fast and inexpensive method for the identification of thermophilic streptococci, RAPD-PCR patterns were generated with a single primer (XD9), and the results were analyzed using artificial neural networks (Multilayer Perceptron, Radial Basis Function network, and Bayesian network) and multivariate statistical techniques (cluster analysis, linear discriminant analysis, and classification trees). Cluster analysis allowed the identification of S. thermophilus but not of enterococci. A Bayesian network proved to be more effective than a Multilayer Perceptron or a Radial Basis Function network for the identification of S. thermophilus, E. faecium, and E. faecalis using simplified RAPD-PCR patterns (obtained by summing the bands in selected areas of the patterns). The Bayesian network also significantly outperformed two multivariate statistical techniques (linear discriminant analysis and classification trees) and proved to be less sensitive to the size of the training set and more robust in the response to patterns belonging to unknown species
La vita ipogea nei suoli vesuviani
Full text linkThis chapter describes the underground life of the Vesuvian soils. Vesuvius, with its frequent eruptions, has given rise to very heterogeneous soils in terms of mineral quality, represented by more than 35 minerals rich in macro and microelements essential for the life of plants and microorganisms. The Vesuvian soils are considered fertile soils for plants crop. In order to be fertile, a soil must not only contain the mineral substances for plant growth, but must possess all the biological actors that allow a soil to be self-sufficient and self-regulate: microorganisms degrading organic matter, bacteria promoting plant growth, “eaters” of bacteria and fungi, nitrogen fixing bacteria of the soil and water and decontaminators of toxic substances.
This high speciographic and functional biodiversity allows the soil to maintain its biological fertility which can only be threatened by spills of toxic and noxious waste, intensive agriculture and poor management of the forest environment
Il vino e la fermentazione alcolica
Full text linkIl consumo di bevande alcoliche ha da sempre accompagnato la storia dell’uomo, riscontrandosi in tutte le civiltà, dalle meno evolute a quelle più progredite. Le scoperte scientifiche del XV secolo hanno messo in luce come tutti i popoli abbiano ampiamente sfruttato il fenomeno della fermentazione di cereali per produrre bevande. Lo stesso vino, inoltre, aveva assunto fin dai tempi più antichi
un valore liturgico presso tutte le civiltà che si erano affacciate al Mediterraneo. Anche oggi, e in misura maggiore rispetto al passato, si fa largo uso di bevande alcoliche ottenute sia da fermentazione che da distillazione di liquidi zuccherini. Le bevande alcoliche fermentate sono caratterizzate dalla presenza di concentrazioni variabili di alcol, ottenute da frutta, semi di cereali e tuberi, mediante la fermentazione di soluzioni zuccherine. Nelle bevande alcoliche fermentate, la presenza di alcol etilico è dovuta ad un processo naturale denominato “fermentazione alcolica”, operato da lieviti, mediante il quale le sostanze zuccherine si trasformano in alcol etilico e anidride carbonica. Per la legislazione italiana (D.P.R. n. 162), può essere denominato “vino” esclusivamente il prodotto ottenuto attraverso la fermentazione alcolica spontanea, totale o parziale, dell’uva fresca, dell’uva ammostata o del mosto d’uva con gradazione alcolica non inferiore ai
tre quinti della gradazione complessiva. Pertanto, con il termine “vino” si indica il prodotto finale di una lunga catena biotecnologica articolata nelle fasi di preparazione del mosto, di fermentazione, di maturazione e di invecchiamento. Ciascuna delle fasi appena menzionate investe fenomeni chimici, chimico-fisici e biologici che si cerca di regolare con tecniche atte a conservare i caratteri
della materia prima e a migliorare la qualità dei vini che ne derivano, anche in considerazione della crescente domanda e del maggiore interesse dei consumatori per un vino di qualità. Sicuramente, la svolta microbiologica ha rappresentato una delle innovazioni tecniche più importanti nella storia dell’enologia, insieme alle osservazioni sugli effetti dell’ossigeno, sui costituenti fenolici e dell’aroma, grazie alla capacità di incidere sul processo di fermentazione. I principali agenti responsabili della fermentazione alcolica sono i lieviti appartenenti al genere Saccharomyces (in particolare Saccharomyces cerevisiae), mentre i batteri lattici sono determinanti per la fermentazione malolattica. Tali microrganismi guidano la vinificazione del succo d’uva e, per questa ragione, osservare e comprendere il loro comportamento in ambiente enologico è di elevata importanza per l’ottenimento di prodotti finiti con caratteristiche organolettiche ottimali. Le interazioni microbiche, infatti, sono di notevole rilevanza in quanto lo sviluppo di microrganismi indesiderati può generare alterazioni e difetti di natura organolettica
Differentiation of Staphylococcus xylosus strains from italian sausages by antibiotyping and low frequency restriction fragment analysis of genomic DNA
No full textThe aim of this study was to identify the strengths and weaknesses of two typing methods, antibiogram typing and low-frequency restriction fragment analysis of genomic DNA, for the differentiation of Staphylococcus xylosus strains. Twenty-eight Staphylococcus xylosus strains isolated from Italian fermented sausages (Naples-type salami) and S. xylosus DSM 20266 (Type strain) and DSM 6179 were analysed. Antibiotyping, recorded on the basis of susceptibility testing of 16 antibiotics, allowed 21 antibiogram-types to be distinguished. Pulsed-field gel electrophoresis techniques combined with DNA digestion by infrequently cutting enzymes such as Sma I produced 21 pattern-types among the 30 strains of S, xylosus analysed. The association of antibiotyping and PFGE typing clearly distributed S. xylosus strains into 30 combinations, showing that all the strains can be differentiated, Thus, the combination of these two techniques, in spite of limitations due to instability of a phenotype-based system, actually turned out to be the most reliable methodological approach for differentiating strains of S. xylosus
DISTRIBUZIONE DELLAVIFAUNA NIDIFICANTE IN ITALIA: PRIMO BOLLETTINO DEL PROGETTO DI MONITORAGGIO MITO 2000, CARDELLINO CARDUELIS CARDUELIS.
No full textDifferentiation of Staphylococcus xylosus strains from italian sausages by antibiotyping and low frequency restriction fragment analysis of genomic DNA
No full textThe aim of this study was to identify the strengths and weaknesses of two typing methods, antibiogram typing and low-frequency restriction fragment analysis of genomic DNA, for the differentiation of Staphylococcus xylosus strains. Twenty-eight Staphylococcus xylosus strains isolated from Italian fermented sausages (Naples-type salami) and S. xylosus DSM 20266 (Type strain) and DSM 6179 were analysed. Antibiotyping, recorded on the basis of susceptibility testing of 16 antibiotics, allowed 21 antibiogram-types to be distinguished. Pulsed-field gel electrophoresis techniques combined with DNA digestion by infrequently cutting enzymes such as Sma I produced 21 pattern-types among the 30 strains of S, xylosus analysed. The association of antibiotyping and PFGE typing clearly distributed S. xylosus strains into 30 combinations, showing that all the strains can be differentiated, Thus, the combination of these two techniques, in spite of limitations due to instability of a phenotype-based system, actually turned out to be the most reliable methodological approach for differentiating strains of S. xylosus
Characterization of strains of Leuconostoc mesenteroides by analysis of soluble whole-cell protein pattern, DNA fingerprinting and restriction of ribosomal DNA
No full textOf 215 leuconostocs isolated from field grass, natural whey cultures and water-buffalo milk, 178 were identified as Leuconostoc mesenteroides ssp. mesenteroides while 37 strains could not be identified. Biochemical characterization allowed seven groups to be defined. Representative strains of each group and different habitat and nine reference strains were selected for further analyses. Protein profiles appeared suitable for species discrimination, but did not differentiate between the three subspecies of Leuc. mesenteroides. The technique also showed some differences among equivocal strains. DNA fingerprinting for most strains of Leuc. mesenteroides ssp. mesenteroides examined showed a different restriction pattern from that of the type strain. Ribotyping was not useful for discriminating species and subspecies of the genus Leuconostoc : Leuc. mesenteroides ssp. mesenteroides and ssp. dextranicum showed the same ribopattern as Leuc. lactis while Leuc. mesenteroides ssp. cremoris exhibited a pattern distinct from all the other species examined. On the basis of ARDRA-PCR, two main groups could be distinguished: the larger group included Leuc. mesenteroides, Leuc. lactis, Leuc. pseudomesenteroides and some unidentifiable strains; the second one included Leuc. citreum, Leuc. fallax, Weissela paramesenteroides and some unidentified strains
Specific detection of Leuconostoc mesenteroides subsp. mesenteroides with DNA primers identified by random amplified polymorphic DNA (RAPD) analysis
No full textRandomly amplified polymorphic DNA analysis using primer 239 (5* CTGAAGCGGA 3*) was performed to characterize Leuconostoc sp. strains. All the strains of Leuconostoc mesenteroides subsp. mesenteroides (with the exception of two strains), two strains formerly identified as L. gelidum, and one strain of Leuconostoc showed a common band at about 1.1 kb. This DNA fragment was cloned and sequenced in order to verify its suitability for identifying L. mesenteroides subsp. mesenteroides strains
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