Antimicrobial activity of lactobacillus species isolated from kefir

Kefir, a fermented milk product, has been traditionally consumed for its potential health benefits (Rimada and Abraham, 2001). The word kefir is said to have originated from the Turkish word 'Keif' which means 'good feeling'. Kefir is produced with an original native starter (kefir grains) (Beskova et al., 2002; Frengova et al., 2002). Kefir is defined as the yogurt of the 21(st) century (Gorski, 1994). The kefir grains consist of slimy materials in which yeast and bacterial cells are firmly embedded. The lactic acid bacteria, yeast and polysaccharide 'kefiran' that make up the keflr grains have been described as a symbiotic community that impart unique properties to kefir (Beskova et al., loc. cit.; Frengova et al., loc. cit.). Probiotic strains should also have desirable antibiotic resistance and sensitivity patterns, be antagonistic toward potentially pathogenic microorganisms and have metabolic activities benefical to the well being of the host (Ronka et al., 2003). Microorganisms present in the grains are called probiotic because they are benefical to human health (Simova et al., 2002). Lactobacillus species are frequently said to have health-promoting effects in the human and animal intestinal tract. Their probiotic effects have been reported to inhibit pathogenic bacteria, reduce colon cancer, increase the immune response, and decrease serum cholesterol. In addition, it has also been reported that they produce antimicrobial substances or bacteriocins that inhibit undesirable pathogens causing diarrhoea or other diseases in the human intestine (Lee, et al., 2003). The aim of this study was to investigate the antimicrobial activities of lactobacilli isolated from kefir. In addition, antimicrobial activity was studied against two other pathogens, Escherichia coli and Staphylococcus aureus, which may cause gastrointestinal disease (Lee et al., loc. cit.; Alexander and Hudson, 2001; Coutino-Rodriguez et al., 2001).