Le varianti A1 e A2 della ?-caseina non hanno un effetto significativo sul microbiota del latteThe A1 and A2 ?-casein variants have not impact on milk microbiota

Objective: Milk is composed by a complex microbiota which can be influenced by numerous factors such as the season, the diet, the type of litter, the facility. As well, the animal's genotype can affect the composition of the milk microbiota. In milk, ?-casein is characterized by a high-level of polymorphism. The aim of this study was to verify if A1 and A2 ?-casein variants could in- fluence the milk microbioma. Materials and methods: Thirty Holstein cows were genotyped for ?-casein locus and divided into three groups. In two different sea- sons, milk samples (individual and bulk tank for each experi- mental group) and mozzarella cheese were collected separately from each group. Bacterial DNA was extracted from milk and che- ese samples and analysed by MAGGIO/GIUGNO/2020 using metagenomic approach. Results: On taxonomic basis, milk and mozzarella cheese samples showed own bacterial diversity, regardless of the ?-casein va- riants. Significative differences were observed during the sea- sons between milk and cheese samples with the prevalence of Firmicutes in winter and Proteo- bacterium in summer. Conclusions: These preliminary results revealed that the envi- ronment had a stronger impact on the milk microbioma composition rather than animals' genotype.