نوع مقاله : مقاله های پژوهشی
نویسندگان
1 کارشناس ارشد، گروه زیستشناسی، دانشکدهی علوم، دانشگاه اصفهان، اصفهان، ایران
2 استاد، گروه زیستشناسی، دانشکدهی علوم، دانشگاه اصفهان، اصفهان، ایران
چکیده
عنوان مقاله [English]
نویسندگان [English]
Background: Kefir is a probiotic organism that produces jellylike grains as during growth. The grains contain both lactic acid bacteria and yeasts. These microorganisms are surrounded by a polysaccharide matrix named kefiran. Kefiran is a water-soluble branched glucogalactan which has been reported to have antibacterial, antimycotic, and antitumor activity. Methods: Kefir grains were constantly cultured in pasteurized milk. They were then harvested and washed with 100°C and 50°C distilled water. The mixture was centrifuged and the polysaccharide in the supernatant was precipitated by addition of cold ethanol. The precipitate was finally dissolved in hot distilled water and lyophilized. The samples were tested for estimation of proteins by Bradford method. Antimicrobial activities of kefiran extract were evaluated using the well diffusion method with several indicator strains. The effects of proteolytic enzymes on the antimicrobial activity of the extract were also determined. Findings: Both extracts (purified at 100°C and 50°C) had inhibitory effects on the growth of indicator bacteria. Although Bradford test showed the existence of proteins in the extract, the antimicrobial effects of the extract were resistant to proteolytic enzymes. Conclusion: Antimicrobial activity of kefiran extract may depend on its protein component. Keywords: Probiotic, Kefir grains, Kefiran, Antimicrobial activity
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