Genotypic characterization of lactic acid bacteria isolated from traditional Pecorino Siciliano cheese.

摘要

A total of 468 lactic acid bacteria (LAB) isolates from the interior of 6 traditional Pecorino Siciliano cheeses during ripening (1, 30 and 90 days) were characterized genotypically in order to assess the biodiversity within this wild microbial population. PCR and PFGE were used for genetic typing of isolates. Of the 468 isolates, species-specific PCR analysis showed that 79, 58, 2, 9 and 4 isolates reacted with primers for Lactobacillus paracasei, L. plantarum, L. pentosus, L. rhamnosus and L. curvatus, respectively and no isolates reacted with the L. casei primers. Genus-specific PCR analysis showed that 59 isolates reacted positively with the lactococcal primers, 221 with the enterococcal primers and 34 with the Leuconostoc primers, 1 with the pediococcal primers and 4 with the streptococcal primers. Enterococci were characterized at species level and 12 of the 221 enterococci isolates showed positive reaction with the E. faecalis species-specific primers, and the remainder 209 isolates reacted positively with the E. faecium species-specific primers. PFGE analysis allowed to identify different strains of L. plantarum and L. paracasei. The strains which reacted positively with L. curvatus, L. pentosus or L. rhamnosus primers gave a unique PFGE pattern. PFGE indicated 52 different band patterns for enterococci, 9 for lactococci, 5 for leuconostocs and 1 for streptococci and pediococci. It is suggested that wild bacterial populations should be preserved in order to protect the traditional raw milk cheese varieties, and to select new specific strains for the dairy industry.