1,721,038 research outputs found
Different Lactobacillus helveticus strain popolations dominate during Grana Padano Cheese-making
No full textI microrganismi del genere Enterococcus negli alimenti: resistenza agli antibiotici e patogenicità opportunistica
No full textMicroorganisms belonging to the genus enterococcus in foods: Antibiotic resistance and opportunistic pathogenicity
No full textBacteria of the genus Enterococcus, or enterococci (formerly the "faecal" or Lancefield group D streptococci) are ubiquitous microorganisms. Enterococci are predominant inhabitants of the gastrointestinal tract of humans and animals and also commonly occur in large numbers in vegetables, plant material, and foods, especially those of animal origin such as dairy products. Although enterococci share a number of useful biotechnological traits (e.g. bacteriocin production, probiotic characteristics), there is no consensus on the significance of their presence in foodstuffs. The potential pathogenicity of enterococci in human clinical infections and their association with endocarditis have recently become a matter of controversy, in spite of the fact that foods containing enterococci have a long history of safe use. The importance of the enterococci for food and public health microbiologists is related to their enteric habitat, their entering the food chain, their antibiotic resistance, and their possible involvement in food-borne illnesses due to the presence of virulence factors, such as production of adhesins and aggregation substances. More detailed studies are still needed to comprehend the epidemiology, the ecological role, and the virulence of enterococci in foods
DNA-based, culture-independent strategies for evaluating microbial comunities in food-associated ecosystem
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Antilisterial Activity by Enterococci in a Model Predicting the Temperature Evolution of Taleggio, an Italian Soft Cheese
No full textEnterococcus ssp. produced broad-spectrum bacteriocins, which were active against Listeria innocua and Listeria monocytogenes. Inhibition of L. innocua in milk by different starter cultures was evaluated. Milk was inoculated with a conventional starter (Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus mixed cultures) as a sole starter or in combination with inhibitory starter cultures (Enterococcus ssp., bacteriocin-producing strains). Tests were performed under a temperature gradient that reproduced the first 55 h of Taleggio cheese manufacturing and in the presence of rennet. Results indicated that satisfactory inhibition of L. innocua was linked to the combined synergistic antimicrobial effect of pH decrease and bacteriocin production. Overall, data suggested that a potential existed for use of the antagonistic activity from enterococci for protection of Taleggio cheese during ripening, when L. monocytogenes may often reach dangerous concentrations. © 1994, American Dairy Science Association. All rights reserved
An optimised and reproducible protocol for rapid DNA exstraction from lactic acid bacteria
No full textSelection of Some Bacteriophage and Lysozyme-Resistant Variants of Lactobacillus helveticus CNRZ 892
No full textDifferent strains of Lactobacillus helveticus were tested for lysozyme resistance, and one out of three (L. helveticus CNRZ 892) showed a concomitant resistance to homologous phage 832-B1 (lysozyme-resistant, Φ832-B 1-resistant). The mechanism of phage resistance acquisition seemed to be related to a decreased phage adsorption as well as to a sharp decrease in plaque-forming ability (less than 10–8). Some lysozyme-resistant and Φ832-B1-resistant derivatives of strain CNRZ 892 lost the ability to ferment galactose and trehalose and showed loss and rearrangement of plasmids. Chemical treatments of L. helveticus CNRZ 892 and some phage-resistant derivatives showed that the accessibility of the phage receptor present in the cell wall of some mutants may be masked by a surface component that was absent in the original strain. The results suggested the possibility of using lysozyme as a selective agent to isolate phage-resistant derivatives from a population of L. helveticus CNRZ 892 sensitive to both lysozyme and bacteriophage. © 1992, American Dairy Science Association. All rights reserved
Enterococci isolated from dairy products: a review of risks and potential technological use.
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