Abstract:

Objective To investigate the types， characteristics， and differences of microflora in various regions of the intestinal tract of the mice with chronic gastritisinfected with Helicobacter pylori （Hp）， and to clarify the related mechanism. Methods Thirty C57BL/6 mice were randomly divided into control group and infection group， and there were 15 mice in each group. The mice in control group were given normal saline， and the mice in infection group were given Hpsuspension with the concentration of 1×10⁹ CFU·mL^－1. After the model was successful builted， the contents of duodenum， jejunum， and colon of the mice in two groups were collected to extract the total DNA， and PCR amplification was performed； the 16SrRNAV3-V4 region was sequenced through high-throughput sequencing technique；the characteristics， differences，and diversities of the microflora in various regions of intestinal tract of the mice in control and infection group were analyzed by α and β diversity analysis. Results The total number of operational taxonomic unit（OTU） in two groups generated by cluster analysis samples was 211. At the phylum level， there were 5 dominant bacteria such as Firmicutes， Bacteroidetes， Actinomyces， proteobacteria， and Verrucomicrobia； compared with control group， the abundances of Actinobacteria in the duodenum， jejunum and colon of the mice in infection group were significantly decreased （P<0.05）.At the genus level，there were 21 dominant bacteria such as Lactobacillus， Staphylococcus， Clostridium Bacillus-ⅩⅣa， Turicibacter， Akkermansia， Bifidobacterium， Saccharibacteria-genera-incertae-sedis， Barnesia， Desulfovibrio， Alternaria， and Mycoplasma and so on； compared with control group， the abundances of Lactobacillus and Bifidobacterium in the duodenum and colon of the mice in infection group were significantly decreased （P<0.05）， and the abundance of Mycoplasma was significantly increased （P<0.05）.The OTU principal component analysis （PCA） results showed that there were no significant differences in the principal components between two groups（P>0.05）.In the Alpha diversity analysis，the shannon index analysis results showed that there were significant differences in the diversities of duodenum and jejunum microflora of the mice between control group and infection group（P<0.01），and the diversity of microflora in infection group was decreased； the simpson index analysis results showed that there were statistically significant differences in the diversities of duodenum， jejunum and colon microflora of the mice between control group and infection group （P<0.05）；and the diversity of microflora in infection group was decreased.The Welch’s t-test analysis results showed that the abundances in various regions of intestinal tract of the mice in two groups had signifricant differences（P<0.05）. Conclusion The types and characteristics of the microflora in various regions of intestinal tract of the mice with chronic gastritis infected with Hp change， the abundance of the probiotics is decreased and the abundance of Mycoplasma is increased. Its mechanism may be related with the changes of intestinal microenviroment，induced by the colonization of Hp.

Key words: Helicobacter Pylori, Gastritis, Intestinal microflora, Mice，C57BL/6, High-throughput sequencing technique