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Microbial Ecology (BIOL 355) > Lecture 13: Animal-Microbes > Flashcards

Lecture 13: Animal-Microbes Flashcards

1
Q

What is the difference between commensalism and mutualism?

A
  • Commensalism: 0/+
  • Mutualism: +/+
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2
Q

What are some examples of positive microbe-animal positive interactions?

A
  • Stinkbug and Pantoea
  • Protozoa and termites (+/+)
  • Marine worms and bacteria (+/+)
  • Herbivore rumen and microbe (+/+)
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3
Q

Explain the protozoan-termite relationship.

A

(+/+)
1. Protozoa live in the gut of termites and wood roaches
- Digest the cellulose ingested by their host
- Produces acetate
2. Termites
- Oxidize the acetate
- Don’t produce cellulase

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4
Q

What type of positive interaction do marine worms and bacteria have? Give specific examples.

A

Both species benefit (+/+)
- Ectosymbiont example: roundworms with Candidatus Thiosymbion ectosymbionts
- Endosymbiont example: segmented worms with Candidatus Thiosymbion endosymbionts

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5
Q

What are ruminants?

A

Herbivorous cud-chewing mammals (ex. goats, deer, cows) with high cellulose diet (indigestible)

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6
Q

What is the rumen?

A

Organ that lacks cellulases, is anaerobic, near neutral pH

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7
Q

Describe the rumen microbiota.

A
  • Complex, dense microbial community
  • Bacteria: cellulose fermenters, starch fermenters
  • Archaea, protozoa, fungi
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8
Q

Explain rumen metabolism.

A
  • Large production of gas removed via eructation
  • VFAs produced and cross into bloodstream
  • Ruminant gains further nutrition (amino acids and vitamins)
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9
Q

What do the tube worm and bacteria each provide for the other in their mutualistic relationship?

A
  • Bacteria provide sugars for worm
  • Worm provides shelter and carbon dioxide
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10
Q

What are some bioluminescent organisms?

A
  • Photobacterium
  • Vibrio species
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11
Q

What are the likely functions of bioluminescent symbioses?

A
  • Species recognition (mating)
  • Feeding lures (deep sea fish)
  • Counterillumination (predation, camouflage)
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12
Q

What do the bobtail squid and Vibrio each provide for the other in their mutualistic relationship?

A
  • Squid provides shelter and nutrients for Vibrio
  • Vibrio provides camouflage
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13
Q

Describe the mutualistic relationship between mollusca and bacteria.

A

Snails, clams, and mussels gill tissue have chemosynthetic symbionts

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14
Q

What do the aphids and Buchanera aphidicola each provide for the other in their mutualistic relationship?

A
  1. Aphids
    - Feed on phloem sap, which is rich in carbs but poor in most amino acids except glutamine
    - Drop sugar water feces
  2. Buchanera aphidicola
    - Intracellular endosymbionts (reside in bacteriocytes)
    - Can make all amino acids for host aphid
    - Use the glutamine from aphid to make arginine
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15
Q

What are some examples of phototrophic associations?

A

Host/Symbiont
- Cnidarians –> zooxanthellae
- Sponges –> cyanellae
- Molluscs –> zoonxanthellae

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16
Q

Explain the mutualistic relationship between coral polyps and zooxanthellae.

A
  • Zooxanthellae live in the tentacle epidermal tissue
  • Zooxanthellae fix carbon –> facilitate the calcification of the reef structure
17
Q

What is coral bleaching? What are the possible causes?

A
  • Death of zooxanthellae –> corals lose pigment
  • Temperature and disease
18
Q

What are some examples of commensalism involving humans?

A
  1. Lactobacillus in human intestines
    - They get our extra food but we are not hurt by it
  2. Corynebacterium in human eyes
    - Eat our dead skin cells but we are not hurt by it
  3. Staphylococcus epidermidis
    - Use the dead skin cells of the human skin for nutrients
19
Q

Define microbiome.

A

The collection of microorganisms living in and on the body, along with their genetic material

20
Q

What are the effects of the human gut microbiome on human nutrition?

A
  1. Metabolically most active human organ
  2. Microbes makeup ~30% of fecal matter
  3. Microbes help digest food
  4. Fermentation produces VFAs
  5. Microbes supply vitamin B12 & K
  6. Modified bile acids - steroid metabolism
  7. Gases - CO2, CH4 and H2S
21
Q

Explain oral biofilm succession.

A
  • Acidic glycoprotein film from saliva
  • Initially Colonized by Streptococcus spp.
  • Later colonized by others (Fusobacterium, Spirochetes,
    Actinomycetes)
  • Anaerobiosis is maintained by poor oxygen diffusion through plaque biofilm
  • Dental caries/periodontal disease can result
22
Q

What are some examples of negative animal-microbe interactions? (i.e. predation and parasitism)

A
  • Ants eating fungi
  • Fungi eating nematodes

Microbial Ecology (BIOL 355) (17 decks)

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