NSLAB bacterial cannibalism to survive during cheese ripening

摘要

Lactic acid bacteria (LAB) are utilized in cheese manufacture due to their ability to primarily metabolize lactose into lactic acid, and to contribute to cheese flavour development during ripening. Starter lactic acid bacteria (SLAB) are generally thermophilic microflora added to milk at the beginning of cheese manufacture. Non-starter lactic acid bacteria (NSLAB) are generally mesophilic microflora coming from raw milk and from the environment as a result of contamination during the manufacturing procedure. During cheese making SLAB and NSLAB dynamically evolve according to modifications of environmental conditions. In Parmigiano Reggiano (PR), a PDO long-ripened Italian cheese, the number of SLAB commonly exceed 9 log CFU/g of cheese at the end of curd acidification. NSLAB populations, whose initial numbers are typically below 2 log CFU/g begin to grow and eventually plateau at cell densities of 6-7 log CFU/g after 3-9 months of aging (De Dea Lindner et al., 2008). The presence of different amount of LAB, starter and non starter, is the result of microbial ability to grow in milk and curd, and of bacterial cell autolysis (Fox et al., 1996).