Determination of lactic microflora of kefir grains and kefir beverage by using culture-dependent and culture-independent methods

Abstract

In this study, we investigated the bacterial compositions of kefir grains and kefir beverages collected from different regions of Turkey by using culture-independent and culture-dependent methods. In the culture-independent detection, 10 different species of bacteria were detected in total by using the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis of the 16S rRNA gene V3 region. Among these species, Lactobacillus kefiranofaciens was the most dominant one in the kefir grains, while Lactococcus lactis was found to be significantly prevalent in the kefir beverages. In the culture-dependent detection, the primary differentiation and grouping of the isolates from kefir beverages and kefir grains were performed using repetitive sequence-based PCR (rep-PCR) fingerprinting, and the results were validated by 16S rDNA full-length sequencing. According to the results of culture-dependent methods, the most frequently isolated species were L. lactis, Leuconostoc mesenteroides, and Lactobacillus kefiri, respectively. Only 3 species, which are L. lactis, Lactobacillus acidophilus, and Streptococcus thermophilus, were detected with both culture-dependent and culture-independent methods. This study showed that the combination of both methods is necessary for a detailed and reliable investigation of microbial communities in kefir grains and kefir beverages.

Practical application: Due to their artisan- and region-dependent microflora, kefir products can be a source of interesting lactic acid bacteria, either new taxa or strains with specific functional properties, which might be used for the development of new starter cultures and innovative food products. Therefore, an increasing demand exists for new strains that show desirable effects on the product characteristics Artisan dairy products are a candidate source of such microorganisms. For this reason, in this study, the bacterial compositions of kefir grains and kefir beverages obtained from different regions of Turkey were studied using culture-dependent and culture-independent molecular methods.