The physiological importance of the colonic microflora

Area of Science:

• Microbiology
• Gastroenterology
• Animal Science

Background:

• The intestinal microflora is a complex ecosystem comprising approximately 500 strains, many uncultured due to anaerobic and fastidious requirements.
• It exists in close association with the intestinal epithelium and crypts, influencing host physiology.
• Germfree animal models provide a unique system to study the microbiome's functions.

Purpose of the Study:

• To review the current understanding of the intestinal microflora's composition and its physiological significance.
• To highlight the differences observed in germfree animals compared to conventional counterparts.
• To emphasize the utility of germfree animals in gastroenterological research, including disease models.

Main Methods:

• Review of existing literature on intestinal microflora and germfree animal studies.
• Comparative analysis of physiological and metabolic differences between germfree and conventional animals.
• Exploration of germfree models in research areas like carcinogenesis and inflammatory bowel diseases.

Main Results:

• The intestinal microflora has a significant mass, comparable to a major organ.
• Germfree rodents exhibit caecum enlargement and altered metabolism of bilirubin, mucin, and pancreatic enzymes.
• Absence of microflora impacts fatty acid, bile acid, cholesterol, and steroid hormone metabolism.

Conclusions:

• The intestinal microflora is integral to host metabolism and gut health.
• Germfree animals are invaluable tools for dissecting the microbiome's role in physiological processes and diseases.
• Wider adoption of germfree models is recommended for studying microbiome-host interactions.