The effect of kefir produced from natural kefir grains on the intestinal microbial populations and antioxidant capacities of Balb/c mice

Abstract

Kefir is a probiotic and fermented dairy product authentically produced from kefir grains. Kefir grain, as a natural starter culture, contains numerous lactic acid bacteria, acetic acid bacteria and yeasts within a polysaccharide structure. True kefir is a miraculous food in terms of its favorable contributions to human health. However, kefir starter cultures used in industrial kefir productions contain very few lactic acid bacteria and yeasts. These starter cultures do not contain characteristic kefir bacteria, such as Lactobacillus kefiranofaciens, Lactobacillus kefiri, and Lactobacillus parakefiri. The objective of this study was to compare the intestinal microorganisms of BALB/c mice fed kefir produced from natural kefir grains and kefir produced from starter culture. The mice in kefir groups were fed an oral dose of 0.3 mL kefir/day for 15 days, and the control group did not receive kefir. The feces were collected in metabolic cages, and the lactic acid bacteria, yeasts-fungi, and Lactobacillus acidophilus and Bifidobacterium species were determined. Additionally, PCR analysis based on yeast-fungus 23S rRNA was carried out, and serial analysis was performed with an ABI 3100 Genetic Analyzer. Serum total antioxidant status (TAS), serum total oxidant status (TOS) levels, malondialdehyde (MDA) levels and myeloperoxidase (MPO) levels were determined. The mean lactic acid bacteria (LAB) contents of the feces samples obtained from the mice fed kefir samples produced from kefir grains and starter culture were 9.08 log cfu/g and 7.32 log cfu/g on the 15th day, respectively. Mold was found in both the starter kefir group and in the control group (range, 1.91-2.02 log cfu/g). The mold was identified as Trichoderma koningii, a potential human pathogen and carcinogen. It was very impressive that mold was not observed in the feces samples of the mice fed the kefir produced from kefir grains. The highest TAS value was determined in the serum samples of mice fed kefir produced using kefir grains. MPO values in the small intestines of mice fed kefir produced using starter culture were higher than those in the CK group that was associated with possible inflammation. This study might lead to new studies focused on the antifungal effects of kefir and on the importance of using kefir grains in the production of kefir.

Keywords: Antioxidant capacitiy.; Intestinal microorganism; Kefir; Kefir grains; Probiotic; Trichoderma koningii.