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Slow milk coagulating variants of Lactobacillus helveticus
No full textCuring experiments were performed onLactobacillus helveticus strain ATCC 15009 in order to find a correlation between the presence of three extrachromosomal elements and specific phenotypic traits. Mitomycin C treatment of the strain was found to result in an appearance of slow-coagulation variants unable to coagulate milk in 24 h at 42 °C. The effect of mitomycin C on phenotypic and genotypic characteristics ofL. helveticus was therefore further examined. The presence of mitomycin C appeared to act on the proteolytic system of the strain: slow variants exhibited a poor casein breakdown (50 % less) compared with the parental strain. Aminopeptidase activity and lactose utilization were unaffected. The phenotypic variation is possibly due to a point mutation of genetic patrimony. No loss of plasmid DNA was detected after mitomycin C treatment and the restriction pattern of plasmid and chromosomal DNA of the variants, after digestion with several restriction endonucleases, was identical to that obtained for the parental strain
Application of FISH technology for microbiological analysis: current state and prospects
No full textIn order to identify and quantify the microorganisms present in a certain ecosystem, it has become necessary to develop molecular methods avoiding cultivation, which allows to characterize only the countable part of the microorganisms in the sample, therefore losing the information related to the microbial component which presents a vitality condition, although it cannot duplicate in culture medium. In this context, one of the most used techniques is fluorescence in situ hybridization (FISH) with ribosomal RNA targeted oligonucleotide probes. Owing to its speed and sensitivity, this technique is considered a powerful tool for phylogenetic, ecological, diagnostic and environmental studies in microbiology. Through the use of species-specific probes, it is possible to identify different microorganisms in complex microbial communities, thus providing a solid support to the understanding of interspecies interaction. The knowledge of the composition and distribution of microorganisms in natural habitats can be interesting for ecological reasons in microbial ecology, and for safety and technological aspects in food microbiology. Methodological aspects, use of different probes and applications of FISH to microbial ecosystems are presented in this review
Classification techniquesfor the evaluation of DNA fingerprinting of lactic acidbacteria of dairy origin
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Microbiologia delle uova e degli ovoprodotti
No full textL’uovo costituisce uno degli alimenti di origine animale più completi dal punto di vista nutrizionale e più diffusi nelle diete di tutto il mondo, grazie alla sua versatilità d’impiego in diverse formulazioni e al suo basso costo. La valutazione della sicurezza e della qualità di questo prodotto è fondamentale a causa della sua intrinseca deperibilità e dell’elevata probabilità di contaminazione lungo la filiera produttiva e
distributiva. In questo capitolo vengono affrontati e approfonditi gli aspetti igienici relativi alla produzione e trasformazione dell’uovo e dei suoi derivati, nonché alcune informazioni relative alla normativa che ne regolamenta il settore
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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