Mechanism Of Wheat Bran Dietary Fiber On Human Intestinal Bacteria

The number of human symbiotic microorganisms reaches 4×10¹⁴,and the human gut microbiota accounts for more than 90%.Prior studies have shown that wheat bran dietary fiber is composed of hexose and pentose,which can improve the structure and function of gut microbiota.The degree of polymerization?DP?is a major indicator relating to the physical and chemical structure of dietary fiber.However,the influence of hexose with different DP on human gut bacteria warrants assessment.Some scholars believe that,as the main ingredients in wheat bran,arabinoxylan oligosaccharides may be the key to the beneficial effects of WB on the intestinal microbiota.However,it is unclear whether xylo-oligosaccharides or xylan in wheat bran play a vital role in the gut microbiota.The content of ferulic acid in wheat bran ranks second in the grain,which can be used as an ideal substrate to study the ferulic acid esterase in the gut bacteria.Therefore,in this study,the main components of wheat bran dietary fiber with different DP and pentose were used for in vitro anaerobic fermentation.Through analysis of physicochemical properties including gas production,pH value,and the concentration of short-chain fatty acid?SCFA?and 16S rRNA sequencing results,the relationship between gut microbiota and wheat bran was explored.And by metagenomic analysis,we mined ferulic acid esterase in the gut microbiota in wheat bran treated fermentation.The main findings are as follows:Explore the relationship between the DP of dietary fiber and gut microbiota.The results show that the DP is proportional to the production of butyric acid in the main metabolite,and is inversely proportional to the relative abundance of probiotics,such as Bifidobacterium,Bacteroides,Streptococcus,and Lactobacillus.While the DP was proportional to the genera Escherichia-Shigella,Fusobacterium,and Dorea significantly.Also,during the in vitro fermentation of carboxymethyl cellulose,Escherichia-Shigella was significantly increased.Therefore,the amount of carboxymethyl cellulose in food should be strictly controlled.And?-glucan and galacto-oligosaccharide can stimulate the growth of many beneficial microorganisms.Wheat bran plays a similar role in the in vitro fermentation of human gut microbiota as xylan and xylooligosaccharides.In the air pressure analysis,the principal component analysis and COG functional analysis,the three treatment groups showed the same trend.In addition,Venn diagram analysis showed that the three treatment groups shared 80%of the core species taxonomic unit?OTU?.And significant difference analysis showed that only the bacteria with lower relative abundance bacteria Dorea,and Bilophila was varied significantly between the three fiber treatments and control,and they were rich in the wheat bran treated fermentation.Significant enrichment of only five clades was detected in these three treatments.Screen genes with ferulic acid esterase function in the human gut microbiota through metagenomic sequencing.The sample DNA of wheat bran treated fermentation was subjected to metagenomic sequencing.After the original sequence was subjected to quality control and host gene removal,a total of86423270 optimized reads were obtained.The number of sequence of splicing assembly contigs was133192.And 11 base sequences with the characteristics of the conserved sequence Gly-X-Ser-X-Gly and the catalytic triad Ser-His-Asp were identified as potential ferulic acid esterase genes.