Microbial diversity of traditional kefir grains and their role on kefir aroma

•A pyrosequencing approach was applied for the identification of bacterial and fungal microflora of four Turkish kefir grains.•Lactobacillus kefiranofaciens was the dominant kefir associated bacterial strain in kefir grains.•Yeast strains dominated the fungal microflora in which Dipodascaceae family was dominant.•Richness in microflora resulted in a diverse volatile compounds in kefir samples produced with these grains.

Kefir grains consist of rich bacterial and fungal microflora responsible for the production of this traditional fermented milk beverage with unique flavour properties. Here, a pyrosequencing approach was applied for the identification of microbial flora of four kefir grains collected from different regions of Turkey and the volatile compounds in kefir samples produced with these grains were determined. Lactobacillus kefiranofaciens presented in all grains at important levels and Enterobacter, Acinetobacter, Enterococcus and Pseudomonas spp. were observed in traditional kefir grains. The fungal microflora of kefir grains was dominated by yeast species and Dipodascaceae family was dominant and Saccharomyces cerevisiae presented in all grains. Other yeast species belonging to Kazachstania, Candida, Issatchenkia and Rhodotorula species were also detected in kefir grains. Volatile compounds of kefir samples were also diverse related to the microbial diversity of kefir grains. This study revealed the rich microflora of Turkish kefir grains and their interactions with the aromatic properties of kefir.