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

Abstract

-A total of 468 lactic acid bacteria (LAB) isolates from the interior of six 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. Two DNA-based technique, 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, Lb. plantarum, Lb. pentosus, Lb. rhamnosus and Lb. curvatus, respectively and no isolates reacted with the Lb. 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 twelve of the 221 enterococci isolates showed positive reaction with the E. faecalis species-specific primers, and the remainder 209 isolates positively with the E. faecium species-specific primers. PFGE analysis allowed to identify different strains of the same species of Lb. plantarum and Lb. paracasei. The strains which reacted positively with Lb. curvatus, Lb. pentosus or Lb. 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. The results suggest that wild bacterial populations should be preserved in order to protect the traditional raw milk cheeses, and to select new specific strains for the dairy industry.

Effect of different salting technologies on the chemical and microbiological characteristics of PDO Pecorino Siciliano cheese

“…Except streptococci, all LAB found in this study are generally reported to be associated with Italian raw ewes' milk cheeses [8,14,39,49].…”

“…In these conditions, the microbiology of aged raw milk cheeses is typically represented by non-starter LAB (NSLAB) [43]. Several studies have been forwarded to the description of NSLAB communities in Italian raw milk ewes' cheeses [12,14,41,49]. However, some other microbial groups, such as Enterobacteriaceae, have been reported in different Mediterranean cheeses made from ewes' raw milk and subjected to a short time of ripening, [23,36].…”

Technological, phenotypic and genotypic characterisation of wild lactic acid bacteria involved in the production of Bitto PDO Italian cheese

“…Thus, the biodiversity of the lactic acid bacteria (LAB) involved in raw milk cheese production is considered to be a fundamental factor for the features and quality of these artisanal products. Sánchez et al 2005;Tilsala-Timisjävi and Alatossava 1997;Van Hoorde et al 2008b;Vernile et al 2008) but, only one document is available on the autochthonous microflora of Bitto cheese without focusing on the technological characterisation (Colombo et al 2010). The aim of the present research was to characterise the indigenous bacterial population of Bitto, in curd and in cheese to investigate the dynamics of wild LAB involved during the production and ripening of this PDO Italian cheese.…”

The Microfloras and Sensory Profiles of Selected Protected Designation of Origin Italian Cheeses

“…Indeed, many of the strains of L. plantarum were abundant during the early stage of ripening and then decreased during ripening, whereas the number of L. paracasei increased or remained constant until 90 days. Strains of L. curvatus were found only in the early stages of ripening (34). The composition of NSLAB species was affected by farm environment and technology, as confirmed by numerous studies based on comparison of different types of Italian cheese made with different farm technologies.…”