Abstract
A combination of culture-dependent and independent methods was used in an attempt to identify the bacteria present in kefir grains and kefir liquid. Culture-independent methods involved direct extraction of DNA by mechanical means from either grains or liquid, followed by PCR amplification and sequencing of 16S rRNA genes. Culture-dependent methods were performed by inoculating samples from both the kefir grains and the kefir liquid to solid media followed by incubation under either aerobic or anerobic conditions in order to selectively enrich aerobic and anaerobic bacteria. Pure cultures were isolated from enriched bacteria and their DNA was extracted for the amplification and sequencing of 16S rRNA genes. Results indicate that kefir grains had a different bacterial composition compared to the kefir liquid. While Lactobacillus kefiranofaciens, Lactobacillus kefiri,Enterococcus faecium and Acetobacter syzygii were found only in the kefir grains,Lactobacillus helveticus was found only in the kefir liquid. On the other hand, Lactococcus lactis subsp. lactis, Leuconostoc mesenteroides and Acetobacter lovaniensis were found to be present in both the grains and the liquid. To the best of our knowledge, this work is the first to report the presence of A.lovaniensis, A. syzygii and Enterococcus faecium in kefir. Key words: Kefir, 16S rRNA gene analysis, bacterial ecology.
Highlights
Kefir is a traditional fermented milk beverage with a characteristic viscous, slightly carbonated and acidic taste (Guzel-Seydim et al, 2000)
Among the seven distinct isolates, L. kefiri, A. syzygii and E. faecium were only recovered from grains while L. helveticus was only recovered from kefir liquid, L. lactis subsp. lactis, L.mesenteroides and A. lovaniensis were recovered from both the grains and the liquid
L. kefiri and A. syzygii were recovered under aerobic conditions while E. faecium was recovered under anaerobic conditions
Summary
Kefir is a traditional fermented milk beverage with a characteristic viscous, slightly carbonated and acidic taste (Guzel-Seydim et al, 2000). In the form of grains, contains a complex flora of microorganisms composed of bacteria and yeasts. When active kefir grains are continuously cultured in milk, they increase in mass and number. A stable microbial population is maintained (Ninane et al, 2005). The association of different microorganisms in kefir was developed by continuous selection over the centuries. These microorganisms compete with other potentially pathogenic microorganisms and produce active substances that inhibit the growth of other bacteria (Lopitz-Otsoa et al, 2006), providing a pathogen-free ecology in kefir
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
