Microbiota dynamics in cheese production

Grana Padano (GP) is a PDO cheese that is made from raw cow’s milk. One of the problem which more frequently affects the production of GP and also other type of cheese with similar production is the “late blowing” that depends from the butyric fermentation product by Clostridia spp. This phenomenon particularly occurred in the fermentation process of GP. Clostridia, in particular C. tyrobutyricum, are inhibited by the addition of lysozyme, a natural bacteriolytic enzyme derived from egg chicken. Aim of this investigation is to characterize the microbiota dynamics in experimental caseification of GP products in controlled critical parameters in GP ripening like clostridial spore count and lysozyme treatment Grana Padano cheeses were producted in a pilot plant. Milk was inoculated with whey starter mixture. Two different variables in ripening conditions were considered: low or high C. tyrobutyricum spore count and lysozyme treatment or not. Aqueous phases were extracted from cheese aliquots at different timepoints and proteins analysed by 1- and 2D-LC MS/MS. Taxonomic group were assigned using sequence homology search on bacterial peptide counts and MEGAN [1]. The characteristic microbial signature results in important differences from ‘natural’ products, suggest also the environment plays a pivotal role in selection of functional microbiota, and it gives new insights to improve characterization of PDO.