Characterization of the human predominant fecal microbiota - With special focus on the Clostridial clusters IV and XIVa

Johanna Maukonen

    Research output: ThesisDoctoral Thesis


    The human gut microbiota is considered to be a complex fermentor with a metabolic potential rivaling that of the liver. In addition to its primary function in digestion, it affects the human host in numerous ways: maturation and modulation of the immune system, production of short-chain fatty acids and gases, transformation of bile acids, formation of vitamins, and also potential formation of mutagenic, toxic, and carcinogenic substances. Commensal bacteria are able to modulate the expression of host genes that regulate diverse and fundamental physiological functions. Thus the indigenous microbial community has an important influence on host physiological, nutritional and immunological processes. The primary aim of this study was to characterize human predominant fecal microbiota with a special focus on Clostridial clusters XIV (Lachnospiraceae, Eubacterium rectale – Blautia coccoides group) and IV (Ruminococcaceae, Clostridium leptum group). The specific aims were: 1) To develop molecular methods for characterization of the human predominant fecal microbiota; 2) To assess the specificity, practicality, and usability of the developed methods for human fecal samples in healthy adults, elderly people, and people having IBS; 3) To assess possible confounding factors in the analysis of human fecal samples. Molecular tools were developed for rapid, sensitive, and highly specific characterization of the human predominant fecal and salivary microbiota. DNA- and rRNAbased denaturing gradient gel electrophoresis methods (DGGE) were developed for Eubacterium rectale – Blautia coccoides group (Erec), rRNA-based DGGE method for predominant bacteria, and DNA-based DGGE methods for Clostridium leptum group (Clept) and Bacteroides spp. In addition, quantitative real-time PCR (qPCR) methods targeting predominant bacteria, Erec-group, Clept-group, Bacteroides spp., bifidobacteria, and Atopobium group were developed.
    Translated title of the contributionIhmisen vallitsevan ulostemikrobiston karakterisointi - Painopiste erityisesti klostridien fylogeneettisissä ryhmissä IV ja XIVa
    Original languageEnglish
    QualificationDoctor's degree
    Awarding Institution
    • Aalto University
    • Saarela, Maria, Supervisor, External person
    Print ISBNs978-951-38-7954-9
    Electronic ISBNs978-951-38-7955-6
    Publication statusPublished - 2012
    MoE publication typeG5 Doctoral dissertation (article)


    • human fecal microbiota
    • human salivary microbiota
    • DGGE
    • qPCR
    • IBS
    • elderly people
    • GOS
    • DNA-extraction
    • Erec
    • Clept
    • Bacteroides spp.
    • bifidobacteria
    • lactobacill

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