[First part: the intestinal microbiota].

Area of Science:

• Microbiology
• Human Physiology
• Gastroenterology

Background:

• The human gastrointestinal tract harbors a vast and diverse microbial community, co-evolving with the human genome.
• The large intestine plays a critical role in human health, largely influenced by its resident microbial composition.
• The human body is a complex ecosystem comprising both human and bacterial cells.

Purpose of the Study:

• To highlight the significance of the gut microbiota in human health and disease.
• To explain the processes occurring in the large intestine related to microbial fermentation.
• To emphasize the impact of microbiota composition on host physiology and immune response.

Main Methods:

• Review of existing literature on human gastrointestinal microbiota.
• Analysis of microbial fermentation processes in the large intestine.
• Discussion of the interaction between host and microbiota.

Main Results:

• The large intestine is a dynamic environment for microbial activity, including carbohydrate and protein fermentation.
• Key fermentation products include short-chain fatty acids (SCFAs), gases, and other metabolites essential for bacterial growth.
• The gut microbiota is integral to the development and regulation of the immune response.

Conclusions:

• A well-balanced gut microbiota is essential for maintaining gastrointestinal and overall health in humans.
• Disruption of the host-microbiota interaction can lead to various intestinal and extraintestinal diseases.
• Understanding the gut microbiome's role is vital for developing therapeutic strategies.