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Background: Fructooligosaccharides (FOS) have been identified as important prebiotics. Previous studies have found that they can significantly promote the proliferation of Bifidobacterium pseudolongum in the mouse intestine. However, it is still unclear which other bacteria in the mouse intestine can utilize FOS, and the differences in the ability to utilize FOS. In this study, the bacteria capable of utilizing FOS were isolated from mice feces and their ability to utilize FOS was compared. Draft genome sequencing was also applied to explain the differences in FOS utilization at the gene levels., Results: A total of 15 species were isolated from mouse feces and 13 species were able to utilize fructofuranosylnystose (GF2). Eleven species could utilize nistose (GF3), but not Enterococcus hirae and Lactobacillus reuteri. In contrast, 1-kestose (GF4) was hardly utilized. The enzyme activity determination and draft genome sequencing-based analyses revealed that all isolated species used the phosphotransferase system or permease system to transport FOS into the cells before hydrolysis by β-fructofuranosidase. Although β-fructofuranosidase exists in all strains, there are big differences in the corresponding coding genes between bifidobacteria and non-bifidobacteria., Conclusion: Compared with the other isolates, Bifidobacterium species exhibited higher enzyme activity and shorter generation time, leading to a stronger ability to utilize FOS. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

Background: Lactulose was one of the earliest prebiotics to be identified. To assess the potential risk of large intakes of lactulose to the intestinal microbiota, mice were fed a diet containing lactulose (0%, 5% and 15%, w/w) for 2 weeks and the changes in the fecal microbiota were evaluated by 16S rRNA high-throughput sequencing., Results: Lactulose intervention decreased the α-diversity of the fecal microbiota in both low-dose and high-dose groups. The relative abundance of Actinobacteria was significantly increased, while that of Bacteroidetes was significantly decreased after lactulose intervention. At the genus level, the relative abundance of Bifidobacterium belonging to Actinobacteria was significantly increased, and that of Alistipes belonging to Bacteroidetes was decreased in both low-dose and high-dose groups. The relative abundance of Blautia was significantly increased from 0.2% to 7.9% in the high-dose group and one strain of Blautia producta was isolated from the mice feces. However, the strain could not utilize lactulose., Conclusion: Overall, the microbial diversity was decreased after lactulose treatment, with significant increases in the relative abundance of Bifidobacterium. We also provide a strategy to increase the relative abundance of Blautia in the intestine by lactulose feeding at high doses, although the mechanism is not revealed. This will help us understand the prebiotic effect of lactulose on the host health. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

Fructooligosaccharides (FOS) are considered prebiotics and have been proven to selectively promote the growth of Bifidobacterium in the gut. This study aimed to clarify the effects of FOS intake on the composition of luminal and mucosal microbiota in mice. Briefly, mice were fed a 0% or 25% FOS ( w / w )-supplemented diet for four weeks, and the composition of luminal and mucosal microbiota, especially the Bifidobacterium, was analyzed by sequencing the V3-V4 region of 16S rRNA and groEL gene, respectively. After FOS intervention, there were significant increases in the total and wall weights of the cecum and the amount of total short-chain fatty acids (SCFAs) in the cecal contents of the mice. At the phylum level, the results showed a significant increase in the relative abundance of Actinobacteria in the contents and mucosa from the cecum to the distal colon in the FOS group. Besides Bifidobacterium , a significant increase was observed in the relative abundance of Coprococcus in all samples at the genus level, which may be partially related to the increase in butyric acid levels in the luminal contents. Furthermore, groEL sequencing revealed that Bifidobacterium pseudolongum was almost the sole bifidobacterial species in the luminal contents (>98%) and mucosa (>89%). These results indicated that FOS can selectively promote B. pseudolongum proliferation in the intestine, either in the lumen or the mucosa from the cecum to the distal colon. Further studies are required to reveal the competitive advantage of B. pseudolongum over other FOS-metabolizing bacteria and the response mechanisms of B. pseudolongum to FOS.

Fructooligosaccharides (FOS) are a well-known class of prebiotic and are considered to selectively stimulate the growth of bifidobacteria in the gut. Previous studies focused on the growth stimulation of Bifidobacterium , but they did not further investigate the bifidobacterial composition and the specific species that were stimulated. In this study, mice were fed with FOS in different doses for four weeks and the composition of fecal microbiota, in particular Bifidobacterium , was analyzed by sequencing the V3⁻V4 region and the groEL gene on the MiSeq platform, respectively. In the high-dose group, the relative abundance of Actinobacteria was significantly increased, which was mainly contributed by Bifidobacterium . At the genus level, the relative abundances of Blautia and Coprococcus were also significantly increased. Through the groEL sequencing, 14 species of Bifidobacterium were identified, among which B. pseudolongum was most abundant. After FOS treatment, B. pseudolongum became almost the sole bifidobacterial species (>95%). B. pseudolongum strains were isolated and demonstrated their ability to metabolize FOS by high performance liquid chromatography (HPLC). Therefore, we inferred that FOS significantly stimulated the growth of B. pseudolongum in mice. Further investigations are needed to reveal the mechanism of selectiveness between FOS and B. pseudolongum , which would aid our understanding of the basic principles between dietary carbohydrates and host health., Competing Interests: The authors declare no conflict of interest.

BACKGROUND: Fructooligosaccharides (FOS) are a kind of prebiotic. Previous studies concerning the effect of FOS on intestinal microbiota have focused on Bifidobacterium and Lactobacillus. However, the presence of other FOS‐utilizing bacteria makes it necessary to investigate the quantitative changes in these bacterial species in the intestine after FOS intake. In this study, the composition of cecal and fecal microbiota was analyzed using MiSeq sequencing, and the abundance of FOS‐utilizing bacteria was detected using quantitative polymerase chain reaction after the oral administration of FOS. RESULTS: Species‐specific primers for FOS‐utilizing bacteria were designed with superior amplification efficiency for quantification. After FOS intervention, the relative abundance of Bifidobacterium pseudolongum in feces increased to 17.37% and the abundance reached 2.28 × 1010 CFU g−1. The abundance of Bifidobacterium longum and Bifidobacterium breve did not change significantly. Whereas the abundance of Ligilactobacillus murinus decreased, that of Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, and Lacticaseibacillus rhamnosus remained at approximately 104 CFU g−1. CONCLUSION: Species‐specific primers for FOS‐utilizing bacteria were successfully developed, and we confirmed that FOS significantly increased the relative abundance and the abundance of B. pseudolongum in mice, while decreasing the proportion of Lactobacillus. The detection of these species using 16S ribosomal DNA sequencing and quantitative polymerase chain reaction showed the same results. Further investigations are needed to reveal the response of the intestinal microbiota to different FOS compositions. These techniques will contribute to future studies about the composition and dynamics of the intestinal microflora. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]