Isolation, phenotypic and molecular identification of Lactococcus lactis isolates from traditionally produced village cheeses

Abstract

A total of 58 Village cheese samples produced from raw milk without using starter culture in Aydin province have been used for isolation of Lactococcus lactis isolates. For this purpose, a typical colony from each cheese sample representing lactococcus phenotype was confirmed by PCR using specific primers designed for conserved 16S rDNA regions. The number of bacteria growing on M17 agar plates containing nalidixic acid ranged from 1.1 × 107-l .7 × 109 cfu g-1 suggesting that lactococci is widespread in Village cheeses. Catalase activity, microscopy, growing at 10 and 45°C and in the presence of 2, 4 and 6.5% of NaCl were used for phenotypical characterization of isolates. By phenotypical characterization 49 isolates represented lactococcus profile. All isolates were then analyzed by PCR and 29 of them were identified as L. lactis sp. lactis, while only 4 wereL. lactis sp. cremoris. About 16 isolates exhibiting lactococcal profile with phenotypic tests did not give any amplification band with the tested primers however, 2 isolates having atypical phenotype were identified as sp. lactis by PCR. The results of the present study suggest that Lactococcus is the widespread in the flora of village cheeses and would have important role in the formation of desired flavour and textural properties. © Medwell Journals, 2010.