A large variety of cheeses can be produced using different manufacturing processes and various starter or adjunct cultures. In this study, we have described the succession of the microbial population during the commercial production and subsequent ripening of smear-ripened cheese using 16S rRNA gene sequencing. The composition of the microbiota during the first 6 days of production was constant and consisted mainly of LAB (lactic acid bacteria) originating from the starter culture. From day 7, the proportion of LAB decreased as other bacteria from the production environment appeared. From the 14th day of production, the relative proportion of LAB decreased further, and at the end of ripening, bacteria from the environment wholly dominated. These adventitious microbiota included Psychrobacter, Pseudoalteromonas haloplanktis/hodoensis, Vibrio toranzoniae, and Vibrio litoralis (Proteobacteria phylum), as well as Vagococcus and Marinilactibacillus (Firmicutes phylum), Psychrilyobacter (Fusobacteria phylum), and Malaciobacter marinus (Campylobacterota phylum), all of which appeared to be characteristic taxa associated with the cheese rind. Subsequent analysis showed that the production and ripening of smear-ripened cheese could be divided into three stages, and that the microbiota compositions of samples from the first week of production, the second week of production, and supermarket shelf life all differed.

Smear-ripened cheeses are distinguished by their complex microbiota, which play an important role in ripening, flavour development, texture and microbiological safety. Although commercial production typically relies on defined starter and adjunct cultures, microorganisms from the production environment may also shape the product’s characteristics. This study examined the microbial composition of smear-ripened cheeses from six commercial manufacturers using culture and culture-independent techniques, including 16S rRNA gene sequencing and sequencing of internal transcribed spacers. A limited number of microorganisms was recovered by culture, with 37 different isolates identified across all samples. Sequencing of the 16S rRNA gene and internal transcribed spacers revealed 75 and 7 distinct operational taxonomic units, respectively. The microbiota composition reflected the contribution of both mesophilic and thermophilic starter and adjunct cultures, alongside microorganisms originating from the production environment. These included various psychrotrophic bacteria, marine (i.e., osmotolerant) bacteria, and other halophiles from Proteobacteria (Psychrobacter, Pseudoalteromonas, Marinomonas, and Vibrio), Firmicutes (Vagococcus and Marinilactibacillus), Actinobacteriota (Glutamicibacter), Bacteroidota (Winogradskyella and Brumimicrobium), Campylobacterota (Malaciobacter) and Fusobacteriota (Psychrilyobacter) specific to the environment of particular manufacturers. The results indicate that, although pasteurised milk and defined starter cultures are used in commercial production, microorganisms originating from the cheese factory environment form a substantial part of the microbiota of smear-ripened cheese.