Research On Intestinal Flora Influence Mechanism Based On In Vitro Bionic Colon Reactor Omega Racial Fatty Acids

Fatty acids are one of the essential nutrients for the survival of the human body.Among them,the Omega group unsaturated fatty acids such as Docosahexaenoic acid（DHA）and Arachidonic acid（AA/ARA）are important for the human body,especially in the regulation of inflammation.However,the mechanism of how Omega unsaturated fatty acids affect the intestinal flora is not clear due to the long experimental period,invasive nature and inaccurate control of intake in human animal studies.In this study,we investigated the effects of different concentrations and saturations of fatty acids on the intestinal flora and metabolism of healthy adults using a dynamic bionic colonic reactor and in vitro anaerobic fermentation in combination with 16S r RNAomics analysis of intestinal flora for the first time.a new approach to the in vitro study of fatty acids was proposed.The main studies were as follows:（1）Emulsification of four fatty acids.DHA,AA,peanut oil and coconut oil were selected as experimental subjects.Fatty acid emulsions of the four fatty acids were made using polyvinyl alcohol1788,and microscopic observations as well as assays of DPPH radical scavenging ability,hydroxyl radical scavenging ability,superoxide anion radical scavenging ability and reducing power were performed.It was found that these four homogeneous emulsions had uniform distribution of small droplets under microscopic observation and had good antioxidant properties.And they can maintain good stability during the experimental period.（2）Comparative study of the effect of DHA and peanut oil on the growth and metabolism of probiotics.Bifidobacterium breve,Bifidobacterium animalis,Lactobacillus casei and Lactobacillus rhamnosus were used as experimental strains for static in vitro.The growth of the four probiotic strains was compared by anaerobic fermentation.It was found that DHA significantly increased the biomass of Lactobacillus rhamnosus（1.21±0.03）,while lowering the medium p H of Lactobacillus rhamnosus and Bifidobacterium breve more significantly.（3）The effects of four fatty acid saturations on the structural composition of the intestinal flora and the production of metabolites were investigated in an in vitro bionic colonic reactor using fatty acid saturations as the target.It was found that the degree of saturation was significant on the structural composition of the intestinal flora and the production of metabolites（P<0.05）.Among them,peanut oil and DHA possessed high short-chain fatty acid production,and the concentrations of short-chain fatty acids such as acetic acid,propionic acid and butyric acid under the control of DHA(2 m L·L^-1)reached 54.79 mmol·L^-1,8.34 mmol·L^-1 and 1.45 mmol·L^-1,respectively,which varied by 11.48%,-1.41%and 66.98%,respectively,compared with peanut oil.After that,the amount of short-chain fatty acid production decreased with the increase of saturation.And 16S r RNA sequencing showed that the DHA group stabilized the intestinal flora and upregulated beneficial bacterial genera such as Bacillus spp.and Bifidobacterium spp.compared with AA.In addition,unsaturated fatty acids showed higher pro-life properties than saturated fatty acids.（4）The effect of fatty acid concentration on the structural composition of the intestinal flora and the production of metabolites was investigated in an in vitro bionic colonic reactor using the concentration of fatty acids as the target.It was found that the concentration did not have a significant effect on the structural composition of the intestinal flora and the production of metabolites（P>0.05）.However,the higher the concentration of fatty acids,the greater the effect on the abundance of the flora,while the proportion of Firmicutes and Bacteroidota was significantly reduced.Comparing the high and low concentrations of AA,the relative abundance of Proteobacteria increased by 62.5%,and the relative abundance of Firmicutes and Bacteroidota decreased by 23.6%and 26.9%.And with the increase of fatty acid concentration,the total amount of short-chain fatty acids in the peanut oil group was gradually decreasing,and the short-chain fatty acids in the AA and coconut oil groups showed an increasing trend.