Biodiversity in Lactobacillus helveticus strains present in natural whey starter used for Parmigiano Reggiano cheese.

Abstract

Lactobacillus helveticus is the dominant microflora of the natural whey starters used for Parmigiano Reggiano cheese making. The aim of this work was to study the biodiversity of different strains of Lact. helveticus present in six cultures and to compare them with strains of the same species previously isolated from natural whey cultures used for Grana Padano and Provolone cheeses. Twenty different biotypes of Lact. helveticus strains were identified combining the results deriving from SDS-PAGE of cell surface proteins and PCR fingerprinting using M13 as a primer. The biotypes were present in varying amounts in the six natural whey starters and the biodiversity was demonstrated not only within the whey cultures, but also between the whey cultures. Lact. helveticus strains isolated from Parmigiano Reggiano whey cultures analysed by PCR M13, SDS-PAGE and RFLP were distinguishable from Lact. helveticus strains of different dairy origin, namely Grana Padano and Provolone natural whey starters. The presence of different Lact. helveticus biotypes seems to be related to the specific ecosystem of cheese making and may be considered as one of the elements contributing to the typicality of Parmigiano Reggiano cheese.