engleski

Phenotypic and genotypic characterization of indigenous Lactobacillus community from traditional Istrian ewe's cheese

The objective of this study was to describe the diversity of indigenous cultivable community of the lactobacilli associated with production of traditional Istrian cheese and to get a collection of well characterized strains. Raw milk and cheese samples were collected from three different farms in Istria during the ripening. A total of 212 mesophilic and thermophilic lactobacilli isolates as well as bulk colonies (consortia) were investigated using culture dependent approach combining phenotyping and genotyping. Biochemical fingerprinting with PhenePlate-LB system preliminary grouped 212 isolates in 16 distinct PhP types. Only one representative isolate from each PhP cluster was further analyzed by genotyping for a reliable identification at the genus and species level by employing PCR techniques and sequencing of 16S rRNA genes. Sequence analysis of 16S rRNA revealed the presence of Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus casei, Lactobacillus paracasei and Lactobacillus rhamnosus. Lactobacilli were screened for possible resistance against seven selected antibiotics: ampicillin, tetracycline, penicillin, rifampin, clindamycin, erythromycin and vankomycin. Although there was no clear pattern for antimicrobial susceptibility on most tested antibiotics, all representative isolates were resistant to vankomycin. The analysis of bulk colonies by denaturing gradient gel electrophoresis (DGGE) identified Lactobacillus plantarum and Lactobacillus brevis as predominant members of lactobacilli population. Pediococcus pentosaceus, Pediococcus acidilactici, Streptococcus sp. and Leuconostoc mesenteroides were also detected as a part of analysed consortia. The prevalence of identified species and community members of lactobacilli agrees with other studies of raw milk cheeses and represent a usefull base for further selection.

Istrian cheese; lactobacilli; PCR; PCR DGGE; sequencing

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