Evaluation On Defecation Functions Of Banana Oligosaccharides And Study On Their Effects On The Gut Microbiota

Banana(Masa parasdisiac) is a kind of popular fruit with a marketable value. Previous research had shown that oligosaccharides extracted from banana have a significant defecating function. In this paper, oligosaccharides were extracted from two cultivars of banana(Musa AA Pisang Mas and Musa ABB Pisang Awak) separately and two dose groups(2.5 g/(kg· BW· d) and 1.25 g/(kg· BW· d))were set up for each cultivar. Results are showed as follows:(1) Evaluation on the defecation function of banana oligosaccharide(BOS) for the experimental mice: According to ‘‘Handbook of Technical Standards for Testing and Assessment of Health Food in China”, the laxative effect of BOS was studied. Results showed that the CSS(carbon suspension solution) advance ratio in four BOS-dose groups was significantly greater than that in the model group, and the time of the first black dejecta appearance was shorter than that in the model group, suggesting that the two doses of BOS are effective in facilitating bowel movement. The difference between the four dose groups was not significant. Effects of BOS on dejecta moisture content and small intestine moisture content showed no significant difference, suggesting that defecation caused by BOS was not resulted from increasing the moisture content of dejecta and small intestine possibly.(2) The effects of BOS on the major organs of mice: The weight and coefficient of major organs(including heart, liver, spleen, lung, kidney, stomach) of mice were measured; the liver and spleen were extra observed using scanning electron microscopy(SEM). Results showed that neither the difference between the control group and the dose groups, nor the difference between the four BOS-dose groups were found significant, indicating that BOS had no negative effects on the major organs of mice. Combined with former determination of essential factors(changes of body weight, food intake, water intake and so on), it was concluded that BOS had no negative effect on the body and normal activities of mice.(3) The effects of BOS on gut microbiota of mice: Metagenomic strategie was used to evaluate the changes of fecal and intestinal microbial diversity and community composition for BOS feeding mice, and Illumina high-throughput sequencing methods(Mi Seq platform) was used. Operational taxonomic unit(OTU) cluster and abundance analysis showed that the microbiota scales of all 10 samples in fecal and intestinal groups were similar and had great diversity and low evenness. Analysis on microbial community composition showed that the two high dose samples in both feces and intestine groups had respectively lower diversity, suggesting that high dose of BOS could enhance the richness of some species, on the premise that the microbiota scales of all 10 samples were similar. The different curve based on the observed species value, chao value and ACE value also showed that the data produced from all 10 samples could cover all species in the community. Microbial taxonomic analysis showed that the Bacteroidetes and Firmicutes were the major two dominant phylums of both fecal and intestinal microbiota, corresponding to Bacteroidia / Bacteroidales and Clostridia / Clostridiales on class / order level respectively, while intestine group contained two more phylums(Lentisphaerae and Verrucomicrobia) compared to feces group. In feces samples, percentage of Deferribacteres in BOS-dose groups was detected higher than that in control group, while the result was opposite in intestine samples. Among feces samples, percentage of Desulfovibrionaceae and Helicobacteraceae in BOS-dose groups was detected higher than that in control group, while percentage of Lactobacillaceae in dose groups was found higher than that in control group, and the result was the same among intestine samples, inferring that BOS might enhance growth and reproduction of the beneficial bacteria such as Lactobacillaceae and prevent growth and reproduction of harmful bacteria such as Desulfovibrionaceae and Helicobacteraceae. The high dose of Musa ABB Pisang Awak oligosaccharides supplement showed the best effect in probiotics proliferation and harmful bacteria inhibition.