Lecture 15: Microbes

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Questions and Answers

What is the main challenge in studying animal-microbe interactions?

Understanding the mechanisms involving multiple species

Identifying the beneficial effects of microbe interactions on animal outcomes

Assessing outcomes over time in both presence and absence of each interacting partner species (correct)

Determining the exact number of microbe species present

What is the primary difference between parasitism and commensalism?

The presence or absence of harm to one of the species (correct)

The type of microbe involved in the interaction

The direction of benefit between the two interacting species

The duration of the interaction

In a mutualistic interaction, what happens to the host?

It benefits from the interaction (correct)

It is harmed by the interaction

It is not affected by the interaction

It is dependent on the interaction for survival

Which postulates can be used to study the effect of a single microbe species on an animal outcome?

Koch's postulates Signup and view all the answers

What is the term for an interaction where one partner benefits and the other is not affected?

Commensalism Signup and view all the answers

Why is it difficult to determine the outcome of individual resident microbe species in animal-microbe interactions?

Because we can only look at all or none effects Signup and view all the answers

What is the term for an interaction where one partner is harmed and the other benefits?

Parasitism Signup and view all the answers

What is the term for an interaction where both partners benefit?

Mutualism Signup and view all the answers

What is the environment like for a fetus during prenatal development?

In a sterile sac Signup and view all the answers

What is necessary for the maturation of gut tissues, such as EEC, GALT, and ENS?

Microbe signals Signup and view all the answers

Where are major regulatory systems of the body located?

In the gut Signup and view all the answers

What is a result of microbe signals on the gut?

Gut tissue maturation Signup and view all the answers

What is necessary for normal development?

Presence of microbes Signup and view all the answers

What is the role of microbes in the development of immune functions?

Microbes are required for immune function development Signup and view all the answers

What is the primary function of the colon in herbivores and omnivores?

Water resorption and stool formation Signup and view all the answers

What percentage of calories do humans derive from colon microbes?

10-15% Signup and view all the answers

What is unique about the digestive tract of plant-specialists?

Complex with a specialized fermentation chamber Signup and view all the answers

What is the unique characteristic of fermentative metabolism?

High yields of short chain fatty acids Signup and view all the answers

What is the role of bacteria in fibre solubilization?

They break down fibre into simpler compounds Signup and view all the answers

What is the percentage of calories that ruminants derive from rumen microbes?

up to 70% Signup and view all the answers

What is a characteristic of the diet fed to germ-free animals?

Vitamin supplementation and simple carbohydrate profile Signup and view all the answers

What is the primary function of the exocrine secretions in the stomach and small intestine?

Driving digestion Signup and view all the answers

What is the main characteristic of non-starch polysaccharide carbohydrates from plants?

Digestion-resistant Signup and view all the answers

What is the primary function of the intestinal epithelial cells?

Absorption of nutrients Signup and view all the answers

What is the term for substances that are chemically inaccessible to human enzymes?

Indigestible Signup and view all the answers

What is the main reason why plant-based foods are not easily digestible?

Cell wall polysaccharides are digestion-resistant Signup and view all the answers

What is the main difference between human and microbial carbohydrate-degrading enzymes?

Microbes have a wider repertoire of enzymes Signup and view all the answers

What is the term for the storage polysaccharides found in plant cells that are typically digestion-resistant?

Inulin Signup and view all the answers

What is the primary role of bacterial enzymes in the digestion process?

To break down fibre into simple sugars Signup and view all the answers

What are the primary energy sources for animals obtained from plant foods?

Short Chain Fatty acids (Acetate, Propionate, Butyrate and others) Signup and view all the answers

What is the primary function of fermentative metabolism in the digestion process?

To release energy from sugars through fermentation Signup and view all the answers

What is the primary role of the microbiome in obtaining energy and nutrients from plant foods?

To provide accurate predictions of energy and nutrients obtained Signup and view all the answers

What is the primary outcome of mechanical, chemical, and enzymatic digestion of plant foods?

Soluble molecules that are released from the ingested food Signup and view all the answers

What is the primary fate of terminal metabolites in the digestion process?

They are excreted by the animal Signup and view all the answers

What is the primary role of the microbiome in the digestion of plant foods?

To provide energy and nutrients to the animal Signup and view all the answers

What is the primary difference between fatty acids and monoglycerides?

Fatty acids have a chain length of >c10, while monoglycerides are fatty acids with a chain length of Signup and view all the answers

Study Notes

Interactions Between Organisms

Incompatible interactions have no ongoing interaction, while others have at least one partner benefiting and long-term interactions occurring
Interactions can be categorized into parasitism, commensalism, mutualism, and amensalism

Parasitism

One partner benefits, increasing growth output, while the other is harmed, reducing growth output
Examples: parasites and hosts

Commensalism

One partner benefits, increasing growth output, while the other is unaffected
Examples: commensals and hosts

Mutualism

Both partners benefit, increasing growth output
Examples: mutualists and hosts

Microbe Interactions

Microbes collectively influence animal outcomes via mechanisms involving many species
It's difficult to assess outcomes of individual microbe species in animal-microbe interactions
We can assess the effect of all or none of the microbes

Development and Microbes

Microbe signals are required to trigger postnatal gut development
Normal development requires microbes
Microbes are essential for the maturation of gut tissues, immune functions, and major regulatory systems

Gut Development and Microbes

Epithelial cell surface development requires microbes
Gut vascularization and maturation of gut tissues require microbes
Immune functions, such as GALT and IgA secretion, require microbes

Digestion and Microbes

Microbes have a wider repertoire of carbohydrate-degrading enzymes than humans
Multiple microbe species co-operate to solubilize fibre
The gut fermentation produces short-chain fatty acids, which are valuable energy sources for animals

Energy Harvesting and Microbes

Healthy gut microbiomes aid energy harvesting from plant foods
Bacteria have enzymes to solubilize fibre, which animals lack
Fermentative metabolism produces high yields of short-chain fatty acids

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Description

Learn about the different types of symbiotic interactions between organisms, including parasitism, commensalism, and mutualism. Understand the characteristics of each type and how they differ.