7-1: Microbial Communities Flashcards
What is the fundamental niche
Theoretical range of environments where a given microbe could live
What is a realized niche?
Range of environments where a microbe actually lives in the real world
What is responsible for defining the difference between fundamental and realized niches?
Interactions with other microbes
What is co-evolution?
Evolution guided by the nature of relationships between organism
What do we have a poor understanding of in regards to microbial communities?
Which organisms do/don’t interact?
The nature of the relationships?
How relationships change?
What external factors that control relationships?
What is symbiosis?
A close, long-term interaction between different organisms
What is the difference between obligate and facultative symbionts?
Obligate symbionts need the relationship for survival.
Facultative symbionts don’t necessarily require the relationship.
What are lichens?
Slow growing microbial communities with long lifespans.
Comprised of:
a fungus (euk)
an algae (euk) or cyanobacteria
How do fungi benefit in lichens?
The photosynthetic partner produces organic compounds (food) for the fungi.
How do algae/cyanobacteria benefit in lichens?
Fungi acts as an anchor and controlled environment for algae/cyanobacteria.
Help retain water.
Fungus may release lichen acids that dissolve surface compounds to free up inorganic metabolites for the algae/cyanobacteria.
What kind of symbiosis are lichens
Mutualistic
Obligate symbionts = expand ecological range for both
How would lichens be controlled parasitism
Fungi drastically slows partners growth (consume their nutrients)
What is a microbial consortium
Two or more microbes living in a symbiotic relationship
What are two common consortium features in freshwater lakes?
- Numerous non-motile photosynthetic bacteria
- A central motile non-photosynthetic bacterium
What do the motile non photosynthetic bacteria do in a consortium? The photosynthetic?
Motile = positions the consortium in an optimal location for phototroph metabolism
Photosynthetic = provide nutrients to the motile chemoorganotrophs
What are “Chlorochromatium aggregatum”?
Example of a phototrophic consortia that contains a motile B-proteobacterium and green sulfur bacteria (phototrophs)
What is the beta proteobacterium?
Obligate symbiote that has undergone significant gene loss of metabolism genes, but enriched for chemotaxis genes.
What is the green sulfur bacteria?
Phototrophic bacteria that can be cultured, but never observed as free living. Not prosperous without ability to localize to optimal niches.
Where do most prokaryotes live?
Ocean, soil or subsurface (below top layer of soil, or deep marine sediments)
What does soil contain?
Many different micro-environments that support complex, dynamic interactions.
What is cross-feeding?
One organism waste is another’s food
Metabolic processes that require many distinct organisms to complete are called what?
Community-level metabolic processes
