Gut microflora

Microorganisms living in the digestive tracts of humans and other animals

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Gut microflora, also known as the gut microbiota or gut microbiome, refers to the complex community of microorganisms that reside in the digestive tracts of humans and other animals, including insects. The gut microflora is a diverse and dynamic ecosystem that plays a crucial role in maintaining health and influencing disease.

Composition

The gut microflora is composed of trillions of microorganisms, including bacteria, archaea, viruses, and fungi. The majority of these microorganisms are bacteria, with the most common phyla being Bacteroidetes and Firmicutes. Other phyla present include Actinobacteria, Proteobacteria, and Verrucomicrobia.

Bacteria

Bacteria are the most abundant and well-studied members of the gut microflora. They perform essential functions such as fermenting dietary fibers, producing short-chain fatty acids, synthesizing vitamins, and protecting against pathogens.

Archaea

Archaea, particularly methanogens, are less abundant but play a role in the digestion of complex carbohydrates and the regulation of hydrogen levels in the gut.

Viruses

The gut virome consists of viruses that infect bacteria (bacteriophages) and eukaryotic cells. Bacteriophages can influence bacterial populations and gene transfer.

Fungi

Fungi, such as yeasts, are present in smaller numbers and their role in the gut is less understood, but they may contribute to the immune response and nutrient processing.

Functions

The gut microflora performs several vital functions that are essential for host health:

• Metabolic functions: The gut microflora helps in the digestion of complex carbohydrates, the synthesis of vitamins (such as vitamin K and some B vitamins), and the production of short-chain fatty acids like acetate, propionate, and butyrate.

• Protective functions: The microflora acts as a barrier against pathogenic microorganisms by competing for nutrients and attachment sites, and by producing antimicrobial substances.

• Immune system modulation: The gut microflora plays a crucial role in the development and regulation of the host's immune system, influencing both innate and adaptive immune responses.

• Neurological functions: Emerging research suggests that the gut microflora may influence the gut-brain axis, affecting mood, behavior, and cognitive functions.

Factors Influencing Gut Microflora

Several factors can influence the composition and function of the gut microflora, including:

• Diet: Dietary components such as fiber, fat, and protein can alter the composition of the gut microflora.

• Antibiotics: Antibiotic use can disrupt the balance of the gut microflora, leading to dysbiosis.

• Age: The composition of the gut microflora changes throughout life, from infancy to old age.

• Genetics: Host genetics can influence the diversity and composition of the gut microflora.

• Environment: Factors such as geography, lifestyle, and hygiene can impact the gut microflora.

Dysbiosis and Disease

An imbalance in the gut microflora, known as dysbiosis, has been associated with various diseases, including:

• Inflammatory bowel disease (IBD)
• Irritable bowel syndrome (IBS)
• Obesity
• Type 2 diabetes
• Allergies
• Autism spectrum disorders

Research and Therapeutic Approaches

Research into the gut microflora is ongoing, with potential therapeutic approaches including:

• Probiotics: Live microorganisms that confer health benefits when consumed in adequate amounts.

• Prebiotics: Non-digestible food components that promote the growth of beneficial microorganisms.

• Fecal microbiota transplantation: The transfer of stool from a healthy donor to a recipient to restore a healthy gut microflora.

Also see

• Human microbiome
• Probiotics
• Prebiotics
• Fecal microbiota transplantation
• Gut-brain axis