The use of biodiverse autochthonous natural starter cultures to produce typical and PDO cheeses contributes to establishing a link between products and territory of production, which commercial starters, constituted by few species and strains, are not able to. The purpose of this work was the assessment of biodiversity, at strain level, and safety of natural scotta-innesto cultures whose use is mandatory for the Pecorino Romano PDO cheese manufacturing, according to its product specification. The biodiversity of three scotta-innesto, collected in the 1960s and preserved in lyophilised form, was assessed by molecular biotyping using both PFGE and (GTG)5 rep-PCR profiling on 209 isolates belonging to Streptococcus thermophilus (30), Lactobacillus delbrueckii subsp. lactis (72), Enterococcus faecium (87), and Limosilactobacillus reuteri (20), revealing high biodiversity, at the strain level, in the cultures. The cultures' safety was proved through a new approach assessing phenotypic and molecular antibiotic resistance of the cultures in toto, instead of single strains, while the safety of Enterococcus faecium isolates was investigated according to EFSA guidelines. The use of natural biodiverse cultures for the production of microbial starters for typical and PDO cheeses, such as Pecorino Romano, could be an opportunity for recovering the cheese microbiota biodiversity lost during years of commercial starters use.
Keywords: Pecorino Romano PDO; Scotta-innesto; antibiotic resistance; autochthonous cultures; ex situ biodiversity preservation; microbial collections; natural starter cultures.