Identification of Streptococcus infantarius subsp. infantarius as predominant strain responsible for acid production in Izmir Brined Tulum Cheese from Aegean Region of Turkey. Identification of Streptococcus infantarius subsp. infantarius as predominant strain responsible for acid production in Izmir Brined Tulum Cheese from Aegean Region of Turkey

Izmir Brined Tulum (IBT) Cheese is a traditional semi hard raw milk cheese produced in Aegean region of Turkey. In the present study, 216 lactic acid bacteria (LAB) isolates from young and mature IBT cheeses were investigated for their acid production capability with the aim of detecting LAB strains responsible for the acid production in Izmir Brined Tulum cheese. Isolates that displayed acid production ability were identified by using molecular techniques. 16S rDNA sequencing unveiled the precence of LAB species that have never been detected in IBT cheese before and moreover in cheese for the first time as predominant acid producer. Forty two out of 216 isolates decreased the pH of milk below 5.0 in 18 h at 37°C or 42°C. The majority of the acid producing strains from both young and mature cheeses samples were identified as putative S. lutetiensis/S.infantarius subsp. infantarius. Further analysis by sequencing groES/groEL genes of these strains revealed that they are S.infantarius subsp. infantarius. Remaining isolates from young cheese samples were identified as S.macedonicus, S. thermophilus, Lc. lactis subsp. lactis, Lb. delbrueckii subsp. sunkii and Lb. delbrueckii subsp. indicus and from mature cheeses as Enterococcus faecalis and Lb. delbrueckii subsp. sunkii. PFGE results showed large genetic diversity amongst the S. infantarius subsp infantarius isolates recovered from young IBT cheeses. S. infantarius subsp. infantarius strains exhibited better and consistent acidification ability paralleling to S.thermophilus.