Phylogenetic analysis of the human gut microbiota and pathogenic bacteria using ۱۶S rRNA

The human gut microbiota is a large and diverse microbial community that inhabits the gastrointestinal tractand provide multiple benefits for us including nutrient absorption, maturation of the immune system, andalso plays a central role in protection of the host from pathogenic bacterial infection. On the other hand, manyenteric pathogens have developed strategies in order to be able to outcompete the gut community, leading toinfection and/or chronic diseases. Phylogenetic analysis can be effective in choosing the appropriateantibiotics that have the greatest effect on pathogenic bacteria and least impact on the normal human gutflora. The ۱۶S rRNA gene sequences for ۵۰ species of human gut microbiota and pathogenic bacteria weredownloaded from GenBank and aligned using Clustal Omega. The tree was constructed using the Maximumlikelihoodmethod in MEGA-X. Also, bacterial diversity in environmental samples was analyzed using RDPClassifier v.۲.۱۲. The Species of Collinsella aerofaciens, the most abundant actinobacterium in thegastrointestinal tract of healthy humans, are closely related to other normal gut bacterium Bifidobacteriumanimalis. Clostridium, includes several significant human pathogens, are closest strains to genus ofClostridioides which includes Clostridioides difficile, a human pathogen causing an infectious diarrhea.Bacillus cereus cause infections of the gastrointestinal tract and surprisingly, the closest strains to thispathogen are Streptococcus salivarius and Streptococcus viridans which are normal human oral bacteria.Vibrio cholerae share close relationship with the other causal agents of the infections of the gastrointestinaltract, Yersinia, Escherichia coli, Shigella and Salmonella. Campylobacter jejuni closely related toHelicobacter pylori. Based on the phylogenetic analysis there are close relationship between human gutmicrobiota but only some of them are related to gut pathogenic bacteria. In general, this phylogeneticrelationship suggested that human gut microbiota and pathogenic bacteria were originated from the differentancestor.

کلیدواژه ها:

۱۶S rRNA gene ، Normal human gut flora ، Pathogenic bacteria ، Phylogenetic analysis