Microbial Diversity Week 1

Questions and Answers

What is the estimated number of microbial species on Earth?

$10^{14}$

$10^9$

$10^{12}$ (correct)

$10^8$

The human body has more human cells than microbes.

False

What is microbiota?

The total microbial population of a given site or habitat.

What influences the human microbiota?

pH, amount of water, nutrients available, amount of oxygen. Signup and view all the answers

What is the gut-brain axis (GBA) involved in?

Modulating metabolism Signup and view all the answers

The beneficial relationship between two independent organisms is called ______.

mutualism Signup and view all the answers

What is commensalism?

One participant benefits and the other is unharmed. Signup and view all the answers

Dysbiosis can lead to disease.

True Signup and view all the answers

Match the following terms with their definitions:

Mutualism = Both organisms benefit Commensalism = One organism benefits, the other is unaffected Parasitism = One organism benefits at the expense of another Dysbiosis = Disruption of normal microbial balance leading to disease Signup and view all the answers

What role does the skin microbiota play?

Acts as a mechanical barrier to infection. Signup and view all the answers

What type of organisms are primarily found in the mouth microbiota?

Bacteria, including anaerobes. Signup and view all the answers

Study Notes

Microbial Diversity

Estimated microbial species on Earth could be as high as 10^12.
Human body comprises roughly 10^13 human cells to 10^14 microbial cells.

Microbiota vs. Microbiome

Microbiota refers to the total microbial population in a specific habitat (e.g., gastrointestinal microbiota).
Microbiome encompasses the genetic content of the microbiota.

Influencing Factors

Microbial composition affected by pH levels, water availability, nutritional content, and oxygen levels.

Human Microbiota and Health

Microbiota communicate bidirectionally with the gut-brain axis, impacting metabolism, gastrointestinal homeostasis, appetite regulation, stress, anxiety, and memory.
Gut-brain axis helps stimulate immune response, aiding normal immune system development.
Microbiota increase metabolic capabilities and serve as a physical barrier against pathogens by competing for resources and producing antimicrobial substances.

Symbiotic Relationships

Mutualism: Two organisms benefit from each other (e.g., gut bacteria metabolizing undigested carbohydrates, enhancing nutrient availability).
Commensalism: One organism benefits while the other is unaffected (e.g., oral microbiota utilizing sugars without impacting human health).
Relationship can shift to disease state with environmental changes (e.g., dietary changes).
Parasitism: One organism benefits at the host's expense, often transforming symbiotic microbiota into harmful parasites under conditions of dysbiosis.

Microbiota Locations

Skin: Acts as a mechanical barrier to infection, inhospitable to many microbes due to low moisture, high salt concentration, and acidity.
Mouth: Home to complex microbial communities, including 500-600 bacteria types, primarily anaerobes.
Oral cavity serves as an entry point for pathogens targeting the upper respiratory tract.

Description

Explore the intricate interactions between host and pathogens in this first week of our microbiology course. Learn about the vast diversity of microbial species and the roles of microbiota and microbiome in human health. Understand how environmental factors influence microbial populations.