| Stomach is an important digestive organ in human body.There is a microbiota that maintains the microecological stability in the stomach,which is vital to the health of gastrointestinal tract.Chronic gastritis is a common high-incidence gastrointestinal disease,and it may develop into gastric cancer.Exploring the characteristic changes of the microbial community structure in the stomach during the formation of chronic gastritis can provide a theoretical basis for regulating the gastric microbial community to prevent and treat gastritis.Some studies have shown that Helicobacter pylori infection is an important factor in the occurrence and exacerbation of gastritis.Exploring the interaction between other bacteria in the stomach and H.pylori can provide new treatment ideas for the treatment of H.pylori infection by regulating other microorganisms.This study aims to explore the changes in the structure of the microbial community in the stomach during the development of chronic gastritis in the Weihai area of Shandong,discover the bacteria that may play a role in the development of gastritis,and culture and screen the microbes in the stomach to isolate the antagonistic strains of H.pylori and analyze their genomes.The results of the study are as follows:1.16S rDNA genes amplicon sequencing was used,the microbial diversity and community structure in the stomach of patients with chronic gastritis and healthy volunteers were compared and analyzed.Proteobacteria,Firmicutes,Bacteroides and Actinobacteria were the dominant phylum in all samples.At the genus level,both the NAG group and the healthy control group had the highest abundance of Halomonas and Alkaliphilus;the CAG group had the highest abundance of Helicobacter.The CAG group samples can be distinguished effectively from the NAG group samples and the healthy control group samples by PCoA analysis and sample-level cluster analysis.This study found that during the occurrence and development of chronic gastritis,the relative abundance of phylum Proteobacteria,Actinobacteria,Bacteroides,Patescibacteria,Fusobacteria,Acidobacteria and Chloroflexus were increased;the relative abundance of genus Helicobacter,Streptococcus,Ralstonia,Burkholderia,Rhodococcus,Granulicatella,Thermomonas and Actinomyces were increased,indicating that these microorganisms may play a role in promoting the development of chronic gastritis.During the occurrence and development of chronic gastritis,the gene abundance of the COG function of the microbial community in the stomach showed a downward trend.2.Through culture technology,336 strains of bacteria were isolated from gastric mucosal samples,which were distributed in in 5 phyla,43 genera,and 140 species.12 strains that can inhibit the growth of H.pylori were screened out of the isolated strains.Morphological observation of 6 strains showed that they could induce the cell morphology of H.pylori to transform from rod-shaped to spherical.3.The genomes of 6 antagonistic strains of H.pylori were sequenced.The genome sizes of the 6 strains were 2.19Mb-4.67Mb,and the GC content was 38.89%-68.88%.The functional genes,virulence factors,drug resistance genes and metabolic pathways of the 6 strains were obtained by bioinformatics annotation analysis.The prediction of resistance genes found that the genome of strain N4-16-4 contained the most resistance genes.Prediction of virulence genes found that all 6 strains contained multiple virulence factors,most of which were related to adhesion and secretion ability.The pathogenic gene prediction results show that all 6 strains may cause sepsis and tuberculosis in humans.The analysis of secondary metabolite synthesis showed that all 6 strains could synthesize peptide-related secondary metabolites. |
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