| The gut microbiota is the most important and complex micro-ecological system of the human,and it is closely related to the health in human body.The structure of gut microbiota plays an important role in many physiological functions of people,such as metabolism,energy absorption,and immune regulation.There are many factors affecting the composition of the gut microbiota.Among them,dietary habits and nutritional ratio are one of the most important factors.Hydrophilic polysaccharides(HPs)are often used as thickeners and gelling agents in foods.Studies have shown that HPs had abilities such as anti-oxidation,anti-viral,anti-tumor,and it plays an important role in the structure of gut microbiota.However,there are few studies on the effects of HPs on the immune regulation of the host through the gut microbiota.This experiment uses Drosophila as a model,and the culture midium of drosophila adding corn flour-yeast medium is the control group,adding 20 g/L of inulin,5 g/L of xanthan and 10 g/L of konjac flour are the test group.For the experimental group,the effects of polysaccharides on the growth and development of Drosophila and the death of Drosophila were investigated after the intervention of three types of hydrophilic polysaccharides by measuring the average life span,the highest life span,and the adult body length.The effect of polysaccharide on the antioxidant activity of Drosophila was investigated by measuring the MDA content and the SOD activity of 10 days old Drosophila.The effects of polysaccharide on the intestinal immunity of Drosophila were investigated by observing the cell division of intestinal precursor and the expression of antimicrobial peptide gene.The konjac flour with the best effect was selected,and the sequencing of 16 s r DNA was used to investigate the effect of konjac flour on the intestinal flora of Drosophila.The research results are as follows:(1)Feeding inulin,xanthan and konjac flour can prolong the lifespan of Drosophila,promote the growth and development of Drosophila,increase the activity of SOD and reduce the content of MDA,thereby reducing the degree of epidermal lipid peroxidation and improving the antioxidant capacity of cells.The results were gender-differentiated.The life span of females was generally higher than that of males,but the antioxidant capacity was generally lower.The effect of konjac flour group on the lifespan of Drosophila was higher than that of inulin group and xanthan gum group.The average life span of males and femalesincreased by 18.2% and 19.2% respectively in konjac flour group.(2)SDS induced intestinal damage,which caused excessive proliferation of intestinal precursor cells,while inulin group,xanthan gum group and konjac flour group were all significantly(p<0.01)weakened this bad influence.Compared with the control group,the expressions of Defencin,Attac A and Diptericin were up-regulated after feeding with inulin,xanthan gum and konjac flour,and the effects on Cecropin A1 and Cecropin A2 were less.Overall,the expression of the antimicrobial peptide gene can be up-regulated.It has a promoting effect on intestinal immunity.(3)The change of α-diversity in drosophila after ingestion of konjac flour is that the microbial abundance becomes higher,and the change of diversity is not significant(p>0.05).By analyzing the β-diversity through Pco A main coordinates,the gut micobiota structure of the control group was significantly different from the konjac flour group and clustering was formed.Analysis of the composition of gut micobiota showed that after the intake konjac flour,at the level of the phylum,the Bacteroides and Firmicutes increased,but the Proteobacteria and Actinomycetes decreased.At the level of the family,Lactobacillus is reduced and the Lachnospiraceae is elevated.At the genus level,the Stenotrophomonas decreased and the Desuifovibrio was elevated.Comparing the control group and the konjac flour group,the results of LEf Se analysis showed that that there were 6 OUTs in the konjac flour group with significant differences in abundance(p<0.05).The results of KEGG analysis showed that there were 43 different metabolic pathways in the control group and the konjac flour group.The metabolic pathway of cell growth and death and the immune system discussed in the first two chapters rose. |
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