Fig 1.
Phylum-level compositional view of bacteria in three human fecal samples/inocula (–) (F37-1: female, age 37; F37-2: female, age 37; and M54: male, age 54) and corresponding cultures at 6, 9, and 24 h after the initiation of fermentation.
A compositional view of bacterial phyla based on the taxonomic assignment of 16S rRNA genes is shown. Bacterial composition of each sample was estimated from the results of the RDP classifier. Eubacterial 16S rRNA gene copy numbers are shown in the right column; units are copies/wet-g-feces (inoculum) or copies/mL-culture (fermentation).
Fig 2.
Bacterial diversity measures by observed species and Shannon-Wiener index in three human volunteers’ feces (F37-1: female, age 37; F37-2: female, age 37; and M54: male, age 54) and corresponding cultures at 6, 9, and 24 h after the initiation of fermentation.
The Shannon-Wiener diversity index characterizes the diversity in a community, i.e., species abundance and evenness.
Fig 3.
Principal component analysis (PCA) of 16S metagenomic data of bacterial species in three human volunteers’ feces (–) (F37-1: female, age 37; F37-2: female, age 37; and M54: male, age 54) and corresponding cultures at 6, 9, and 24 h after the initiation of fermentation.
F37-1, F37-2, and M54 are indicated in blue, orange, and green, respectively. The numbers indicate the sampling time points.
Fig 4.
(A) Ratios of acetate, propionate, and butyrate in three human volunteers’ feces (F37-1: female, age 37; F37-2: female, age 37; and M54: male, age 54) and corresponding cultures at 24 h after the initiation of fermentation. (B) Time-dependent change of concentrations of short chain fatty acids (SCFAs) in single-batch fermentation cultures.
Values of the ratios are shown as the percentage of the sum of acetate, propionate, and butyrate concentrations.
Fig 5.
16S rRNA gene copy numbers of eubacteria (A, C, E, G, I, and K) and the ratio of genus Bifidobacterium to eubacteria (B, D, F, H, J, and L).
Human feces was used to inoculate cultures in the single-batch fermentation system (feces; F37: A and B; F23: C and D; M38: E and F; F35: G and H; M24: I and J; M43: K and L). Samples are labelled according to the prebiotic oligosaccharides [control (no addition), FOS, GOS, IMO, XOS, raffinose, lactulose, and lactosucrose]. Error bars show standard deviation for mean of triplicates. Asterisks indicate values that are significantly different (p<0.05) from those for the control systems (n = 3) using the Dunnett test.
Table 1.
Changes in production of acetate, propionate, and butyrate after 24 h of fermentation in the single-batch systems using medium supplemented with the prebiotics (FOS, GOS, IMO, XOS, raffinose, lactulose, or lactosucrose).
Samples of human feces (designated F37, F23, M38, F35, M24, or M43) were used to inoculate each system. Changes are presented as the ratio of concentration in the experimental system normalized to that in the control system (without added prebiotics). The control system generated acetate, propionate, and butyrate at concentrations (mean±SD, n = 6) of 104.0±16.3, 28.4±10.1, and 14.8±5.3 mM, respectively.