Small intestinal microbiota: from taxonomic composition to metabolism

Area of Science:

• Microbiology
• Gastroenterology
• Human Microbiome Research

Background:

• The small intestinal microbiota (SIM) plays a vital role in digestion, immunity, and metabolism.
• The SIM remains poorly characterized compared to the colonic microbiota due to sampling difficulties.
• The SIM comprises core genera and segment-specific bacteria interacting closely with the host.

Purpose of the Study:

• To highlight the importance and challenges in studying the small intestinal microbiota.
• To review current understanding of SIM composition and function.
• To identify future research directions for a comprehensive understanding of the SIM.

Main Methods:

• Literature review of existing studies on small intestinal microbiota.
• Analysis of current evidence on SIM composition and bacterial overgrowth.
• Discussion of emerging techniques for SIM investigation.

Main Results:

• The SIM is essential for host health, influencing nutrient absorption and metabolism.
• Two forms of small intestinal bacterial overgrowth (SIBO) exist: oral bacteria-dominated and coliform-dominated.
• The SIM composition varies, with core genera and segment-specific taxa.

Conclusions:

• Further research using advanced techniques is needed to fully understand the SIM.
• Less invasive sampling, omics, and mechanistic studies are key for SIM characterization.
• Improved understanding of the SIM will enable targeted interventions for gastrointestinal health.