title: Survey on the community and dynamics of lactic acid bacteria in Grana Padano cheese.
abstract: Grana Padano (GP) is a Protected Designation of Origin cheese made with raw milk and natural whey culture (NWC) that is characterised by a long ripening period. In this study, six GP productions were considered in order to evaluate the trend of microbial dynamics and compare lactic acid bacteria (LAB) population levels in cheeses during the entire cheese-making process. To reach this goal, for each GP production, samples of vat raw milk, NWC and cheeses at 48h, 2, 6, 9 and 13 months were subjected to plate counts and direct counts by fluorescence microscopy, as well as amplicon length heterogeneity-PCR (LH-PCR). Statistical analysis was applied to the results and ecological indices were estimated. It was demonstrated that the LAB able to grow in the cheese-environment conditions could arise from both raw milk and NWC. Starter lactobacilli (SLAB) from NWC were the main species present during acidification, and non-starter LAB (NSLAB), mainly from milk but also from NWC, were able to grow after brining and they dominated during ripening. The peak areas of LH-PCR profiles were used to determine ecological indices during manufacture and ripening. Among cheese ecosystems with different ageing times, diversity, Evenness and Richness were different, with highest bacterial growth and diversity occurring in cheese ripening at 2 months. At this time point, which seemed to be a crucial moment for GP microbial evolution, cell lysis of both SLAB and NSLAB was also observed. Sampling modality and statistical analysis gave greater significance to the results used to describe the microbiological characteristics of a cheese recognised worldwide.
authors.affiliation: Department of Food Science, University of Parma, Parco Area delle Scienze 48/A, 43124 Parma, Italy.
authors.forename: Marcela
authors.initials: M
authors.lastname: Santarelli
authors.forename: Benedetta
authors.initials: B
authors.lastname: Bottari
authors.forename: Camilla
authors.initials: C
authors.lastname: Lazzi
authors.forename: Erasmo
authors.initials: E
authors.lastname: Neviani
authors.forename: Monica
authors.initials: M
authors.lastname: Gatti
mesh_terms: D058491:Bacterial Load; D058448:Biota; D002611:Cheese / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D014644:Genetic Variation; D056546:Lactobacillales / Q000145:classification* / Q000254:growth & development*; D016133:Polymerase Chain Reaction
chemical_list: D004269:DNA, Bacterial
keywords: CAM; Cheese ripening; Ecological indices; GP; Grana Padano; LAB lysis; LH-PCR; Lactic acid bacteria; Microbial dynamics; NSLAB; NWC; PR; Parmigiano Reggiano; SLAB; cheese agar medium; length heterogeneity-PCR; natural whey culture; non-starter lactic acid bacteria; starter lactic acid bacteria