Relationships among house, rind and core microbiotas during manufacture of traditional Italian cheeses at the same dairy plant

• Lactic acid bacteria were the mainly cultivable bacteria in dairy equipment.
• Streptococcus thermophilus was the main colonizing bacterium.
• Starters showed diverse capacities to colonize Caciotta or Caciocavallo Pugliese cheeses.
• Components of house microbiota differently contaminated rind and/or core cheeses.

This study was aimed at establishing the relationships between house, rind and core microbiotas of cheese varieties manufactured at the same industrial dairy plant. Caciotta and Caciocavallo Pugliese cheeses were chosen as model systems. Mesophilic lactobacilli, cocci and, especially, thermophilic cocci were the most abundant cultivable bacteria found on equipment, which were located in the production area. According to cell counts, catabolic profiles of microbial communities deriving from equipment, and cheese core and rind differed. As shown by 16S rRNA targeted metagenomics, Streptococcus thermophilus dominated the communities from knife surface, brine tank, curds and core cheeses as well as it was the main colonizing bacterium from drain table, rinds and ripening room of Caciocavallo Pugliese cheeses. Compared to S. thermophilus, the other starters used (Lactococcus lactis, Lactobacillus delbrueckii subsp. lactis and Lactobacillus helveticus) showed low relative abundance in cheeses and/or colonization capability. A set of other genera/species, which varied depending on the equipment surfaces and cheese making, contributed to the formation of a rather heterogeneous house microbiota. Representatives from such communities had (e.g., Lactobacillus casei, Lactobacillus plantarum group) or not (e.g., Actinobacteria) the capacity to colonize cheeses, which depended on the variety (Caciocavallo Pugliese or Caciotta cheese) and layer (rind or core). Other genera/species were mainly associated to the rind and ripening room of Caciotta (Staphylococcus species and Brochothrix spp.) or Caciocavallo Pugliese (Chromohalobacter and Sphingomonas) cheeses.