Fac-simile Scheda Linee di Ricerca - Federalimentare

Dati pubblicati inerenti il tema di ricerca:1. Fortina M.G., Ricci G., Foschino R., Picozzi C., Dolci P., Zeppa G., Cocolin L., ManachiniP.L. (2007) Phenotypic typing, technological properties and safety aspects of Lactococcusgarvieae strains from dairy environments. J. Appl. Microb, 103, 445-453To characterize Lactococcus garvieae strains of dairy origin and to determine their technological properties andsafety for their possible use in starter culture preparation. Methods and Results: Forty-seven L. garvieae isolates,recovered from two artisanal Italian cheeses were studied, in comparison with 12 fish isolates andthe type strainof the species. Phenotypic typing revealed that the strains could be differentiated on the basis of their ecologicalniche of origin in lactose positive strains (all isolated from dairy sources) and lactose negative strains (all isolatedfrom fish). Furthermore, the strains exhibited a high degree of physiological variability, showing the presence of26 different biotypes. The strains possessed moderate acidifying and proteolytic activities and did not producebacteriocins. A safety investigation revealed that all strains were sensitive to vancomycin and moderately resistantto kanamycin; some biotypes were tetracycline resistant. Production of biogenic amines or presence of genesencoding virulence determinants occurred in some isolates. Conclusions: The prevalence of L. garvieae in someartisanal Italian cheeses can be linked to the typicity of the products. Although in a few cases an antimicrobial resistanceor a presence of virulence determinants may imply a potential hygienic risk, most of the strains showedpositive properties for their possible adjunction in a starter culture preparation, to preserve the natural bacterialpopulation responsible for the typical sensorial characteristics of the traditional raw milk cheeses. Significanceand Impact of the Study: L. garvieae strains can be considered an important part of the microbial population associatedwith the natural fermentation of artisanal Italian cheeses. A deepened characterization of the strains mayaid in understanding the functional and ecological significance of their presence in dairy products and in selectingnew strains for the dairy industry.2. Dolci P., Alessandria V., Rantsiou K., Rolle L., Zeppa G., Cocolin L. (2008) Microbial dynamicsof Castelmagno PDO, a traditional italian cheese, with a focus on lactic acid bacteriaecology. Int. J. Food Microb., 122, 302-311The dynamics of dominant microflora throughout the manufacture and ripening processes were evaluated in threebatches of traditional Castelmagno PDO cheese. Milk, curd and cheese samples, at different stages duringcheesemaking, were collected and subjected to culture-dependent and –independent analysis. Traditional platingand genetic identification of lactic acid bacteria (LAB) isolates, and PCR-DGGE analysis of V1 region of 16SrRNA gene were carried out. The collected samples were also monitored by HPLC for the presence of organicacids, sugars and ketones. LAB resulted to be the prevailing microflora in all production stages although enterococci,coagulase-negative cocci and yeasts also showed considerable viable counts probably related to the presence,in the dairy samples analysed, of free short-chain fatty acids detected by HPLC. Lactococcus lactis subsp.lactis was the species most frequently isolated during Castelmagno PDO manufacture, while Lactobacillus plantarumand Lactobacillus paracasei were isolated with the highest frequencies from ripened Castelmagno PDOcheese samples. Occasionally strains of Lactobacillus delbrueckii subsp. lactis, Lactobacillus coryniformis subsp.torquens and Lactobacillus casei were isolated. The results obtained on Castelmagno PDO microflora underlinesa partial correspondence between culture-dependent method and DGGE analysis. Thus, in this study, it is highlightedonce more the importance to combine molecular culture-independent approaches with classical microbiologicalmethods for the study of complex environmental communities occurring in food matrices.SISTAL - SOCIETA’ ITALIANA DI SCIENZE E TECNOLOGIE ALIMENTARIDipartimento di Scienze e Tecnologie Agroalimentari, Università degli Studi della TusciaVia San Camillo de Lellis, 01100 ViterboTel.: 0761- 35 74 94/7 , Fax: 0761- 35 74 98, e-mail: mmoresi@unitus.it459