Isolation of lactococcus lactis subsp. lactis and lactococcus lactis subsp. cremoris strains from traditionally made izmir tulum cheese and identification of isolates by phenotypic and molecular techniques

This study was done to isolate strains belonging to the Lactococcus genus from IzmirTulum cheese manufactured according to traditional techniques without using starter bacteriaand to identify the isolates by some phenotypic tests and polymerase chain reaction by usingprimers designed from 16S rDNA. The isolated strains will be used for scientific studies inthe future and selected possible candidates would be employed as starter culture in the cheesemaking.For this purposes, 90 cheese samples were collected from Aydın province betweenMay 2005?May 2006. Cheese samples were transported to the laboratory rapidly andsubjected to microbiological analyses. M17 agar containing 40 ?g/ml was used as the mediafor the isolation of lactococcal strains.The number of colonies growing on the media was found to be varied from 1.9 x 107to 2.1 x 108 cfu/g bacteria. A typical colony representing the appearance of type strain wasselected for the further identification processes. For this purpose the bacteria were picked upfrom the colony and transferred into a tube containing M17 lactose broth and incubated.Thereafter, the bacteria were again plated onto M17 agar. This process was repeated twiceand allowed to purify the isolates. After this process the isolates were subjected to simplebiochemical tests and 36 isolates were represented lactococcus profile. The isolates were thenanalyzed by polymerase chain reaction (PCR) by using subspecies-specific primers allowingdistinguishing lactis and cremoris subspecies. Among the tested isolates 18 gave positiveresult with lactis primers whereas only 11 isolates were confirmed by cremoris primers.