Effectiveness of chemometric techniques in discrimination of Lactobacillushelveticus biotypes from natural dairy starter cultures on the basis of phenotypic characteristics

Lactobacillus helveticus is the dominant organism in natural starter cultur es used for the production of typical Italian cheeses. In this study, 74 L. helveticus strains, isolated from grana and provolone cheese natural whey starters, were distinguished with respect to their origin by using both cel l wall protein profiles and chemometric evaluation of some phenotypic param eters, such as the ability to acidify cultures and the presence of nonspeci fic proteolytic and peptidase activities. Cell wall protein patterns allowe d L, helveticus strains to be distinguished with respect to their source of isolation. Among the different phenotypes studied, no single specific para meter permitted the two groups of strains to be separated. A good discrimin ation between the two groups of L. helveticus species was obtained by multi variate statistical techniques, which permitted the extraction of all of th e discriminating information retained in the phenotypic activities. Associa tions between strain phenotype expression and dairy environmental ecosystem source are discussed.