Lecture 13: Animal-Microbes Flashcards
What is the difference between commensalism and mutualism?
- Commensalism: 0/+
- Mutualism: +/+
What are some examples of positive microbe-animal positive interactions?
- Stinkbug and Pantoea
- Protozoa and termites (+/+)
- Marine worms and bacteria (+/+)
- Herbivore rumen and microbe (+/+)
Explain the protozoan-termite relationship.
(+/+)
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
What type of positive interaction do marine worms and bacteria have? Give specific examples.
Both species benefit (+/+)
- Ectosymbiont example: roundworms with Candidatus Thiosymbion ectosymbionts
- Endosymbiont example: segmented worms with Candidatus Thiosymbion endosymbionts
What are ruminants?
Herbivorous cud-chewing mammals (ex. goats, deer, cows) with high cellulose diet (indigestible)
What is the rumen?
Organ that lacks cellulases, is anaerobic, near neutral pH
Describe the rumen microbiota.
- Complex, dense microbial community
- Bacteria: cellulose fermenters, starch fermenters
- Archaea, protozoa, fungi
Explain rumen metabolism.
- Large production of gas removed via eructation
- VFAs produced and cross into bloodstream
- Ruminant gains further nutrition (amino acids and vitamins)
What do the tube worm and bacteria each provide for the other in their mutualistic relationship?
- Bacteria provide sugars for worm
- Worm provides shelter and carbon dioxide
What are some bioluminescent organisms?
- Photobacterium
- Vibrio species
What are the likely functions of bioluminescent symbioses?
- Species recognition (mating)
- Feeding lures (deep sea fish)
- Counterillumination (predation, camouflage)
What do the bobtail squid and Vibrio each provide for the other in their mutualistic relationship?
- Squid provides shelter and nutrients for Vibrio
- Vibrio provides camouflage
Describe the mutualistic relationship between mollusca and bacteria.
Snails, clams, and mussels gill tissue have chemosynthetic symbionts
What do the aphids and Buchanera aphidicola each provide for the other in their mutualistic relationship?
- Aphids
- Feed on phloem sap, which is rich in carbs but poor in most amino acids except glutamine
- Drop sugar water feces -
Buchanera aphidicola
- Intracellular endosymbionts (reside in bacteriocytes)
- Can make all amino acids for host aphid
- Use the glutamine from aphid to make arginine
What are some examples of phototrophic associations?
Host/Symbiont
- Cnidarians –> zooxanthellae
- Sponges –> cyanellae
- Molluscs –> zoonxanthellae