Bacterial biodiversity in traditional koumiss fermented milk was studied by denaturing gradient gel electrophoresis (DGGE). Target DNA bands were identified according to the reference species ladder, constructed in this study. Comigrating bands present in the DGGE profiles were resolved by species-specific PCR. The results revealed a novel bacterial profile and extensive bacterial biodiversity in koumiss. The dominant lactic acid bacteria included Lactobacillus acidophilus, Lactobacillus helveticus, Lactobacillus fermentum, and Lactobacillus kefiranofaciens. Frequently encountered bacterial species were Enterococcus faecalis, Lactococcus lactis, Lactobacillus paracasei, Lactobacillus kitasatonis, and Lactobacillus kefiri. Leuconostoc mesenteroides, Streptococcus thermophilus, Lactobacillus buchneri, and Lactobacillus jensenii were occasionally found in this product. In addition, L. buchneri, L. jensenii, and L. kitasatonis, which were never previously isolated by culture-dependent methods, were identified for the first time in the Xinjiang koumiss. Furthermore, conventional cultivation was performed by plating samples on M17, de Man-Rogosa-Sharpe, Halligan-Pearce, and Kenner fecal media. The results revealed that lactobacilli were the dominant species in the koumiss ecosystem, which was consistent with the results obtained by the DGGE analysis. This is the first systematic study of the microbial composition in koumiss, and our findings will be helpful in selecting appropriate strains for the manufacture of this product at the industrial level.

The effects of the Kluyveromyces marxianus M3 strain, isolated from Tibetan mushrooms, on plasma lipids, egg cholesterol level, egg quality, and intestinal health of laying hens were evaluated. In total, 160 Beijing fatty laying hens (43 weeks old) were divided into four groups and fed a basal diet supplemented with 0%, 0.1%, 0.3%, or 0.5% freeze-dried K. marxianus M3 powder for four weeks. The results showed that yeast supplementation reduced serum total cholesterol (TC), triglyceride (TG), low density lipoprotein-cholesterol (LDL-C), and very low density lipoprotein-cholesterol (VLDL-C) levels (p<0.01), and increased serum high density lipoprotein-cholesterol (HDL-C) level (p<0.05). Moreover, regardless of K. marxianus M3 dietary addition level, the cholesterol content of the eggs decreased by more than 26%. When0.3% yeast was supplemented, significant differences were found in the egg weights, shell strength, albumen height, Haugh unit and nutrient content of the eggs (p<0.01). Finally, 0.3% yeast supplementation improved the intestinal flora conditions of the hens by decreasing the Salmonella and Staphylococcus aureus counts (p<0.01) and increasing the Bifidobacterium count (p<0.01). The results in this work demonstrated that yeast culture supplementation to the diets deceased the serum and egg yolk cholesterol, and increased egg quality.