Population dynamics of lactobacilli in Grana cheese

Abstract

A survey on the presence, microbial diversity, and population dynamics of lactobacilli in Grana cheese is presented. Evolution of thermophilic rod lactic acid bacteria within the first two days from cheese making and during ripening was different according to different bacterial groups, which were selectively enumerated and identified by molecular methods. Species-specific microbial counts indicated prevalence of Lactobacillus helveticus in both the whey starter and the cheese at moulding, and of Lactobacillus delbrueckii subsp. lactis in cheese after two months of ripening. In more advanced ripening, a decrease of total thermophilic lactobacilli and an increase of mesophilic lactobacilli (mostly belonging to Lactobacillus casei/paracasei and Lactobacillus rhamnosus) was observed. PCR fingerprinting of lactobacilli, which was performed by PCR-fingerprinting, indicated a marked microbial heterogeneity within the Lactobacillus spp. populations, which enabled strain (or group)-specific fingerprints to be observed.