The Effect Of Different Diet On Intestinal Flora Composition In Different Rat Species

Objective:To observe and clarify the changes of the intestinal flora diversity and community composition in different rat species feeding on different diet using the454high-throughput sequencing method, Simultaneously by studying whether the diet impact the intestinal flora differently between the two rat species, we aim to provide more data for studying the reason why different human races show difference in the risk of development of certain diseases (obesity, inflammatory bowel disease) even feeding on a same diet.Methods:A total of120weaned Bal b/c mice and SD rat were enrolled, in which the intestinal flora is still in the stage of establishment We take five different special dietary interventions for two months. The fresh stool samples of each group were collected, and the total fecal bacterial genomic DNA were extracted. The sequence of VI-V3hypervariable region in bacterial16SrRNA gene was amplified by polymerase chain reaction. Electrophoresis was used to purify the PCR products. Mixing the PCR products after quantitation according to the requirements of the amount of each sample. Finally, we sent them the to Shanghai Kyrgyzstan biomedical technology company for futher454GS FLX sequencing.Results:Diversity analysis showed that the total number of OTU and bacterial diversity were lowest in high-fiber diet group in both the Bal b/c mice and SD rats. Taxonomic analysis showed that the Firmicutes and Bacteroides were the major two dominant phylums of intestinal microflora in all diet groups. In terms of Balb/c mice, the relative abundance of phylum Firmicutes was highest in the normal diet group, while lowest in the high-fiber diet group. The proportion of Firmicutes in the normal diet group was significantly higher than that in other diet groups. Followed by high-sugar diet group and the high-fat diet group, the proportion of bacteria in these two diet groups were significantly higher than that in the high-fiber group, and high-protein group. The proportion of Firmicutes between high-fiber group and high-protein group is not different significantly.The relative abundance of Bacteroidetes was highest in the high-fiber diet group, while lowest in the normal diet group. The proportion of Bacteroidetes in High-fiber diet group, high-protein diet group and high-sugar diet group were significantly higher than that in the normal diet group. The proportion of Bacteroidetes in high-fiber, high-protein diet group were significantly higher than that in high-sugar, high-fat diet group.But there is no significant difference between high-fiber and high-protein diet group, as well as the high-fat and high-sugar diet group. Although the proportion of Proteobacteria in all diet group was low, but the proportion of which in high-fiber diet group was significantly lower than that in the normal and the high-fat diet group. In terms of SD rats, the relative abundance of Firmicutes was lowest in the high-fiber diet group, while was highest in the high-fat diet group. Firmicutes proportion among groups ranked as: high-fat diet group> high-sugar diet group> normal diet group> protein diet group> high-fiber diet group, the proportion of Firmicutes in high-fat diet group was significantly higher than that in high-protein and high-fiber diet group. The proportion of Firmicutes in high-fiber was significantly lower than that in the high-fat and high-sugar diet group The relative abundance of Bacteroidetes was lowest in the high-fat diet group, while was highest in the high-fiber diet group. The proportion of Bacteroidetes in each group ranks as followes:high-fiber diet> high-protein diet group>normal diet group> high-sugar diet>high-fat diet group. The proportion of Bacteroidetes in high-fiber diet group was significantly higher than that in the normal diet group, high-sugar group and high-fat group. Followed by the high-protein diet group, in which the proportion of Bacteroidetes was significantly higher than that in the high-fat diet group.There was no significant difference of the proportion of Bacteroidetes between the high-sugar, high-fat and the normal diet group.Conclusion:The high-fiber diet cause decrease of community abundance and diversity of intestinal flora in both SD rats and Bal b/c mice. Firmicutes and Bacteroides were the major dominant phylum in all diet group, which the ratio of Firmicutes and Bacterodetes was different in different diet group. The effect of diet on intestinal flora diversity and community composition was different in different rat species.