Alteration of a human intestinal microbiota under extreme life environment in the Antarctica.

The human intestinal microbiota (HIM) settles from birth and continues to change phenotype by some factors (e.g. host's diet) throughout life. However, the effect of extreme life environment on human HIM composition is not well known. To understand HIM fluctuation under extreme life environment in humans, fecal samples were collected from six Japanese men on a long Antarctic expedition. They explored Antarctica for 3 months and collected their fecal samples at once-monthly intervals. Using terminal restriction fragment length polymorphism (T-RFLP) and real time polymerase chain reaction (PCR) analysis, the composition of HIM in six subjects was investigated. Three subjects presented restoration of HIM after the expedition compared versus before and during the expedition. Two thirds samples collected during the expedition belonged to the same cluster in dendrogram. However, all through the expedition, T-RFLP patterns showed interindividual variability. Especially, Bifidobacterium spp. showed a tendency to decrease during and restore after the expedition. A reduction of Bifidobacterium spp. was observed in five subjects the first 1 month of the expedition. Bacteroides thetaiotaomicron, which is thought to proliferate during emotional stress, significantly decreased in one subject, indicating that other factors in addition to emotional stress may affect the composition of HIM in this study. These findings could be helpful to understand the effect of extreme life environment on HIM.

Identification of Human Intestinal Microbiota of 92 Men by Data Mining for 5 Characteristics, i.e., Age, BMI, Smoking Habit, Cessation Period of Previous Smokers and Drinking Habit.

The intestinal microbiota compositions of 92 men living in Japan were identified following consumption of identical meals for 3 days. Fecal samples were analyzed by terminal restriction fragment length polymorphism with 4 primer-restriction enzyme systems, and the 120 obtained operational taxonomic units (OTUs) were analyzed by Data mining software focusing on the following 5 characteristics, namely, age, body mass index, present smoking habit, cessation period of previous smokers and drinking habit, according to the answers of the subjects. After performing Data mining analyses with each characteristic, the details of the constructed Decision trees precisely identified the subjects or discriminated them into various suitable groups. Through the pathways to reach the groups, practical roles of the related OTUs and their quantities were clearly recognized. Compared with the other identification methods for OTUs such as bicluster analyses, correlation coefficients and principal component analyses, the clear difference of this Data mining technique was that it set aside most OTUs and emphasized only some closely related ones. For example for a selected characteristic, such as smoking habit, only 7 OTUs out of 120 were able to identify all smokers, and the remaining 113 OTUs were thought of as data noise for smoking. Data mining analyses were affirmed as an effective method of subject discrimination for various physiological constitutions. The species of bacteria that were closely related to heavy smokers, i.e., HaeIII-291, were also discussed.

Effects of green tea consumption on human fecal microbiota with special reference to Bifidobacterium species.

Green tea is one of the most popular beverages in the world. Its beneficial health effects and components have been extensively reviewed. However, little is known about the influence of green tea consumption on the human intestinal microbiota (HIM), which plays a crucial role in human health. Ten volunteers who did not usually consume green tea, drank it for 10 days and then stopped drinking it for 7 days. Their fecal samples were collected at three time points: before beginning the 10-day green-tea regime, at the conclusion of that 10 days, and 7 days after stopping the regime. Their fecal samples were analyzed by terminal restriction fragment length polymorphism with specific primer-restriction enzyme systems for HIM and by using a real-time PCR method for the Bifidobacterium species. Although the HIM of each subject was relatively stable, the proportion of Bifidobacterium species played an important role in the classification of their fecal microbiota. Although there were inter-individual differences in the Bifidobacterium species, an overall tendency for the proportion of bifidobacteria to increase because of green tea consumption was noted. However, little change was observed in the composition of Bifidobacterium species in each sample. This suggests that the change in proportion was induced, not by an inter-species transition, but by an intra-species increase and/or decrease. In conclusion, green tea consumption might act as a prebiotic and improve the colon environment by increasing the proportion of the Bifidobacterium species.