36 Questions
What is the main challenge in studying animal-microbe interactions?
Assessing outcomes over time in both presence and absence of each interacting partner species
What is the primary difference between parasitism and commensalism?
The presence or absence of harm to one of the species
In a mutualistic interaction, what happens to the host?
It benefits from the interaction
Which postulates can be used to study the effect of a single microbe species on an animal outcome?
Koch's postulates
What is the term for an interaction where one partner benefits and the other is not affected?
Commensalism
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
What is the term for an interaction where one partner is harmed and the other benefits?
Parasitism
What is the term for an interaction where both partners benefit?
Mutualism
What is the environment like for a fetus during prenatal development?
In a sterile sac
What is necessary for the maturation of gut tissues, such as EEC, GALT, and ENS?
Microbe signals
Where are major regulatory systems of the body located?
In the gut
What is a result of microbe signals on the gut?
Gut tissue maturation
What is necessary for normal development?
Presence of microbes
What is the role of microbes in the development of immune functions?
Microbes are required for immune function development
What is the primary function of the colon in herbivores and omnivores?
Water resorption and stool formation
What percentage of calories do humans derive from colon microbes?
10-15%
What is unique about the digestive tract of plant-specialists?
Complex with a specialized fermentation chamber
What is the unique characteristic of fermentative metabolism?
High yields of short chain fatty acids
What is the role of bacteria in fibre solubilization?
They break down fibre into simpler compounds
What is the percentage of calories that ruminants derive from rumen microbes?
up to 70%
What is a characteristic of the diet fed to germ-free animals?
Vitamin supplementation and simple carbohydrate profile
What is the primary function of the exocrine secretions in the stomach and small intestine?
Driving digestion
What is the main characteristic of non-starch polysaccharide carbohydrates from plants?
Digestion-resistant
What is the primary function of the intestinal epithelial cells?
Absorption of nutrients
What is the term for substances that are chemically inaccessible to human enzymes?
Indigestible
What is the main reason why plant-based foods are not easily digestible?
Cell wall polysaccharides are digestion-resistant
What is the main difference between human and microbial carbohydrate-degrading enzymes?
Microbes have a wider repertoire of enzymes
What is the term for the storage polysaccharides found in plant cells that are typically digestion-resistant?
Inulin
What is the primary role of bacterial enzymes in the digestion process?
To break down fibre into simple sugars
What are the primary energy sources for animals obtained from plant foods?
Short Chain Fatty acids (Acetate, Propionate, Butyrate and others)
What is the primary function of fermentative metabolism in the digestion process?
To release energy from sugars through fermentation
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
What is the primary outcome of mechanical, chemical, and enzymatic digestion of plant foods?
Soluble molecules that are released from the ingested food
What is the primary fate of terminal metabolites in the digestion process?
They are excreted by the animal
What is the primary role of the microbiome in the digestion of plant foods?
To provide energy and nutrients to the animal
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
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
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.
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