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126 results on '"Varisco, G."'

5. Validation of a real-time PCR method on pta gene for Clostridium tyrobutyricum quantification in milk

Author

Arnaboldi, S., Benevenia, R., Bertasi, B., Galuppini, E., Mangeri, L., Tilola, M., Bassi, Daniela, Cocconcelli, Pier Sandro, Stroppa, A., Varisco, G., Bassi D. (ORCID:0000-0001-9020-3853), Cocconcelli P. S. (ORCID:0000-0003-2212-7611), Arnaboldi, S., Benevenia, R., Bertasi, B., Galuppini, E., Mangeri, L., Tilola, M., Bassi, Daniela, Cocconcelli, Pier Sandro, Stroppa, A., Varisco, G., Bassi D. (ORCID:0000-0001-9020-3853), and Cocconcelli P. S. (ORCID:0000-0003-2212-7611)

Abstract

In the dairy industry, the late blowing defect in medium and long ripened cheeses causes important economic losses. This cheese defect, caused mainly by the anaerobic spore former Clostridium tyrobutyricum, is characterized by gas production resulting in holes formation in the paste, and in unpleasant aromas related to the butyrate production. Since longtime, the reference method used to detect the presence of total spore number in milk is the Most Probable Number (MPN), a semi-quantitative method which measures the bacterial growth and the gas production after heat treatment of the samples. This method often gives uncertain results, it requires long incubation periods and fails to differentiate between different species of spore-forming bacteria. A TaqMan real-time quantitative PCR targeting the phosphotransacetylase gene (pta) for C. tyrobutyricum was previously developed as an alternative technique to the traditional method, faster and more specific, and therefore of great interest to preventively determine the contamination of milk by C. tyrobutyricum. The aim of this work was the validation of this quantitative real-time PCR protocol for the C. tyrobutyricum detection in milk. Following the method validation, 120 samples of UHT and raw milk artificially contaminated with C. tyrobutyricum spores were analyzed in increasing concentrations, relating the results of the molecular method with those obtained by the MPN. Finally, 144 raw milk samples with a possible natural contamination were analyzed and demonstrated a positivity rate of 15.28% (CI95% 10.31–22.05%).

Published
2021

25. Effect of intramammary infection in Bergamasca meat sheep on milk parameters and lamb growth

Author

Moroni, Giuliano G., Varisco G., and Boettcher P.J.

Abstract

Pooled milk samples from 115 Bergamasca meat sheep were collected aseptically five times from lambing to weaning to determine the prevalence of intramammary infection, somatic cell counts and milk quality parameters (protein, fat and lactose), and effects of infection on lamb weight gain. The global prevalence of subclinical intramammary infection was 51.2%. The Staphylococcus genus was responsible for the greatest prevalence (53.3% among infected udders). Staphylococcus aureus was isolated in 8.4% of infected milk samples. Infection status had significant effects on fat and protein percentage and on somatic cell count. Lamb growth was greatest for lambs of ewes with no infection and decreased as the number of infected samples increased. No significant differences were detected in the growth of lambs with dams infected by different bacterial species.

Published
2007

39. Hepatitis A outbreak in Italy associated with frozen berries

Author

De Medici, D, primary, Alfonsi, V, additional, Bruni, R, additional, Busani, L, additional, Ciccaglione, AR, additional, Di Pasquale, S, additional, Equestre, M, additional, Escher, M, additional, Ricotta, L, additional, Rizzo, C, additional, Scavia, G, additional, Taffon, S, additional, Tosti, ME, additional, Pompa, MG, additional, Martini, V, additional, Iannazzo, S, additional, Losio, MN, additional, Varisco, G, additional, Pavoni, E, additional, Massaro, M, additional, Cappelletti, B, additional, Noè, P, additional, Menghi, A, additional, Guizzardi, S, additional, Lena, R, additional, Plutino, G, additional, Monteleone, D, additional, and Borrello, S, additional

Published
2014
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49. Water transport into PEFC gas diffusion layer: experimental characterization of diffusion and permeation.

Author

Bresciani, F., Casalegno, A., Varisco, G., and Marchesi, R.

Subjects
PROTON exchange membrane fuel cells, DIFFUSION, PERMEATION tubes, CATHODES, PROTON conductivity
Abstract

SUMMARY Optimization of water management in low-temperature polymer electrolyte fuel cells is an important subject for the achievement of high performance and sufficient lifetime. Indeed, good hydration of the electrolyte membrane is essential for high proton conductivity; on the contrary, water in excess may lead to electrode flooding especially at the cathode where water is produced. Water transport through the gas diffusion layer, from cathode electrode to distributor flow field, occurs via diffusion and permeation mechanisms: these phenomena are not fully explained, and the onset of the second one, usually named as breakthrough, can play an important role on cathode water balance. This work aims to investigate diffusive and permeative water transport through the diffusion layer under fuel cell representative operating conditions. The effect of microporous layer on diffusion layer effective diffusivity is estimated, and the contribution of the Knudsen diffusion is evaluated. The microporous layer presence determines a strong increase in breakthrough pressure; moreover, cracks are responsible for breakthrough. At high water saturation in the diffusion layer, a considerable hysteresis effect on breakthrough pressure is present. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2014
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