Cheese microbial biodiversity

Specificity and sensory characteristics of traditional cheeses are strictly related to the high level of biodiversity of the indigenous microbiota which results from the selective pressure carried out by the environment, the livestock conditions and the cheese-making technology. In particular, lactic acid bacteria (LAB) represent a fundamental factor affecting the quality of artisanal products. In the last decades the improvement of sanitary conditions, cleaning and sanitation of milking equipment as well as proper cooling of milk, led the farms to produce raw milk with reduced microbial count, but in the meantime it entailed an important impoverishment of LAB. Microbial biodiversity preservation represents one the main missions of CNR-ISPA Milano, which has a collection of over 2000 LAB strains, isolated over the last 3 decades from milk and traditional raw milk cheeses. All strains were typed by molecular analysis and assessed for their antibiotic resistance pattern. Wide differences in technological properties are present between and inside the species. Wild strains are characterized by different technologically relevant biochemical properties such as acid production and redox activity, lipolytic and proteolytic activities in milk, but also for their flavour enhancing capabilities and their antagonism against (potential) pathogenic and spoilage microorganisms. The knowledge of such traits is a key factor determining the success when developing and producing tailor-made starter cultures for different traditional cheese products. In this sense, the starter culture manufacturers Sacco and CSL are constantly working in strict contact with research institutes and traditional milk products manufacturer and consortia, selecting and producing only those microorganisms that allow preserving the overall quality, shelf-life and safety of traditional cheese. Having a culture collection with more than 6000 strains, the starter manufacturers can provide cheese producers with phage-unrelated starter cultures that can be used in rotation to