Microbiology - Lecture 23 - Microbiomes

What is the human microbiome?

The collection of all microorganisms (bacteria, fungi, viruses, and others) that live in and on the human body.

Where is the human microbiome found?

On the skin, in the mouth, gut, respiratory tract, and urogenital tract.

What is the most diverse and dense microbiome in the body?

The gut microbiome.

What is the difference between microbiome and microbiota?

Microbiota refers to the community of microbes; microbiome includes their genes, environment, and interactions.

Why is the microbiome important?

It aids digestion, produces vitamins, trains the immune system, and protects against pathogens.

What are commensal microbes?

Microbes that live in or on the body without causing harm.

What are mutualistic microbes?

Microbes that provide benefits to the host while also benefiting themselves.

What are opportunistic pathogens?

Normally harmless microbes that cause disease when the immune system is weakened or barriers are broken.

What are transient microbes?

Microbes that temporarily colonize the body and are removed by immune defenses or hygiene.

What are resident microbes?

Microbes that permanently live on or in the body and play protective roles.

What are some benefits of the gut microbiome?

Helps digest complex carbohydrates, synthesizes vitamins (like B and K), and supports immune function.

How does the microbiome protect against pathogens?

By competing for nutrients and attachment sites, and by producing antimicrobial compounds.

How does the microbiome influence the immune system?

It helps train immune cells to recognize harmless vs harmful microbes.

What is dysbiosis?

An imbalance in the microbiome that can lead to disease.

What can cause dysbiosis?

Antibiotic use, poor diet, stress, or infection.

What are some conditions linked to dysbiosis?

Inflammatory bowel disease (IBD), obesity, allergies, and autoimmune disorders.

What are probiotics?

Live beneficial microbes that can be consumed to restore a healthy microbiome balance.

What are prebiotics?

Nutrients (like fiber) that feed beneficial microbes in the gut.

Examples of probiotic sources?

Yogurt, kefir, sauerkraut, and other fermented foods.

Examples of prebiotic sources?

Whole grains, fruits, vegetables, and legumes.

What is the relationship between antibiotics and the microbiome?

Antibiotics can disrupt normal microbiota, leading to overgrowth of resistant or harmful microbes.

What is an example of infection caused by microbiome disruption?

Clostridium difficile (C. diff) infection after antibiotic treatment.

How can C. diff infections be treated?

With targeted antibiotics or fecal microbiota transplants (FMT).

How does the skin microbiome protect against pathogens?

It produces antimicrobial peptides and maintains an acidic environment.

What influences the composition of the skin microbiome?

Moisture, pH, temperature, and hygiene habits.

What affects the microbiome throughout life?

Birth method (vaginal vs C-section), diet, environment, antibiotics, and age.

How does the microbiome differ in vaginal vs C-section birth?

Vaginal birth exposes babies to maternal microbes; C-section results in more skin and environmental microbes.

How does diet shape the microbiome?

High-fiber diets support beneficial bacteria, while high-fat or processed diets can reduce diversity.

What is the relationship between the gut and brain called?

The gut-brain axis.

How does the gut-brain axis work?

Gut microbes communicate with the brain through the nervous system, hormones, and immune signals.

What mental health conditions are linked to microbiome changes?

Anxiety, depression, and autism spectrum disorders.