Here, we used pyrosequencing to obtain a detailed analysis of the microbial diversities of traditional fermented dairy products of Mongolia. From 22 Airag (fermented mare’s milk), 5 Khoormog (fermented camel’s milk) and 26 Tarag (fermented milk of cows, goats and yaks) samples collected in the Mongolian provinces of Arhangai, Bulgan, Dundgobi, Tov, Uburhangai and Umnugobi, we obtained a total of 81 operational taxonomic units, which were assigned to 15 families, 21 genera and 41 species in 3 phyla. The genus Lactobacillus is a core bacterial component of Mongolian fermented milks, and Lactobacillus helveticus, Lactobacillus kefiranofaciens and Lactobacillus delbrueckii were the predominant species of lactic acid bacteria (LAB) in the Airag, Khoormog and Tarag samples, respectively. By using this pyrosequencing approach, we successfully detected most LAB species that have been isolated as well as seven LAB species that have not been found in our previous culture-based study. A subsequent analysis of the principal components of the samples revealed that L. delbrueckii, L. helveticus, L. kefiranofaciens and Streptococcus thermophilus were the main factors influencing the microbial diversity of these Mongolian traditional fermented dairy products and that this diversity correlated with the animal species from which the milk was sourced.
The composition of the intestinal microbiota was measured following consumption of identical meals for 3 days in 92 Japanese men, and terminal restriction fragment length polymorphism (T-RFLP) was used to analyze their feces. The obtained operational taxonomic units (OTUs) and the subjects’ ages were classified by using Data mining (DM) software that compared these data with continuous data and for 5 partitions for age divided at 5 years intervals between the ages of 30 and 50. The DM provided Decision trees in which the selected OTUs were closely related to the ages of the subjects. DM was also used to compare the OTUs from the T-RFLP data with seven restriction enzymes (two enzymes of 516f-BslI and 516f-HaeIII, two enzymes of 27f-MspI and 27f-AluI, three enzymes of 35f-HhaI, 35f-MspI and 35f-AluI) and their various combinations. The OTUs delivered from the five enzyme-digested partitions were analyzed to classify their age clusters. For use in future DM processing, we discussed the enzymes that were effective for accurate classification. We selected two OTUs (HA624 and HA995) that were useful for classifying the subject’s ages. Depending on the 16S rRNA sequences of the OTUs, Ruminicoccus obeum clones 1-4 were present in 18 of 36 bacterial candidates in the older age group-related OTU (HA624). On the other hand, Ruminicoccus obeum clones 1-33 were present in 65 of 269 candidates in the younger age group-related OUT (HA995).
Remarkable LAB-yeast mixed-species biofilm was formed by lactic acid bacteria (LAB) Lactobacillus plantarum ML11-11 isolated from Fukuyama pot vinegar and Saccharomyces cerevisiae. This mixed-species biofilm formation increased in proportion to the YPD medium concentration but decreased in proportion to the MRS medium concentration. The effect of MRS components on mixed-species biofilm formation was investigated in a YPD medium environment, and it was clarified that beef extract (one of the MRS medium components) decreased mixed-species biofilm formation. On the other hand, manganese sulfate (another component in MRS) remarkably increased both LAB single- and LAB-yeast mixed-species biofilm formation. LAB single- and mixed-species biofilm formation were increased in proportion to the manganese sulfate concentration up to 1 mM and 100 μM, respectively. The growth of L. plantarum ML11-11 was increased significantly by the addition of 10 μM manganese sulfate and was resistant to higher concentration of up to 100 mM, but growth of S. cerevisiae was sensitive to manganese ion above 100 μM. These results suggested that mixed-species biofilm formation could be controlled artificially by controlling the manganese ion level.
To optimize culture conditions that enhance production of a highly viscous exopolysaccharide of Lactobacillus fermentum TDS030603, a chemically defined medium was examined. The best yield was found to be 199 ± 23 mg/l when 48-hr cultivation was microaerobically performed at 30°C in the chemically defined medium supplemented with 5% glucose and 1% ammonium citrate without pH control. In response to the optimized exopolysaccharide production, the mRNA expression levels of epsB, epsE, and epsG elevated significantly. Our results indicated that the optimal C/N ratio and/or microaerobic condition can alter the expression levels of several exopolysaccharide biosynthesis-related genes promoting the exopolysaccharide production yield.
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