7-1: Microbial Communities

Question 1

What is the fundamental niche

Answer 1

Theoretical range of environments where a given microbe could live

Question 2

What is a realized niche?

Answer 2

Range of environments where a microbe actually lives in the real world

Question 3

What is responsible for defining the difference between fundamental and realized niches?

Answer 3

Interactions with other microbes

Question 4

What is co-evolution?

Answer 4

Evolution guided by the nature of relationships between organism

Question 5

What do we have a poor understanding of in regards to microbial communities?

Answer 5

Which organisms do/don’t interact?
The nature of the relationships?
How relationships change?
What external factors that control relationships?

Question 6

What is symbiosis?

Answer 6

A close, long-term interaction between different organisms

Question 7

What is the difference between obligate and facultative symbionts?

Answer 7

Obligate symbionts need the relationship for survival.

Facultative symbionts don’t necessarily require the relationship.

Question 8

What are lichens?

Answer 8

Slow growing microbial communities with long lifespans.
Comprised of:
a fungus (euk)
an algae (euk) or cyanobacteria

Question 9

How do fungi benefit in lichens?

Answer 9

The photosynthetic partner produces organic compounds (food) for the fungi.

Question 10

How do algae/cyanobacteria benefit in lichens?

Answer 10

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.

Question 11

What kind of symbiosis are lichens

Answer 11

Mutualistic
Obligate symbionts = expand ecological range for both

Question 12

How would lichens be controlled parasitism

Answer 12

Fungi drastically slows partners growth (consume their nutrients)

Question 13

What is a microbial consortium

Answer 13

Two or more microbes living in a symbiotic relationship

Question 14

What are two common consortium features in freshwater lakes?

Answer 14

1. Numerous non-motile photosynthetic bacteria
2. A central motile non-photosynthetic bacterium

Question 15

What do the motile non photosynthetic bacteria do in a consortium? The photosynthetic?

Answer 15

Motile = positions the consortium in an optimal location for phototroph metabolism
Photosynthetic = provide nutrients to the motile chemoorganotrophs

Question 16

What are “Chlorochromatium aggregatum”?

Answer 16

Example of a phototrophic consortia that contains a motile B-proteobacterium and green sulfur bacteria (phototrophs)

Question 17

What is the beta proteobacterium?

Answer 17

Obligate symbiote that has undergone significant gene loss of metabolism genes, but enriched for chemotaxis genes.

Question 18

What is the green sulfur bacteria?

Answer 18

Phototrophic bacteria that can be cultured, but never observed as free living. Not prosperous without ability to localize to optimal niches.

Question 19

Where do most prokaryotes live?

Answer 19

Ocean, soil or subsurface (below top layer of soil, or deep marine sediments)

Question 20

What does soil contain?

Answer 20

Many different micro-environments that support complex, dynamic interactions.

Question 21

What is cross-feeding?

Answer 21

One organism waste is another’s food

Question 22

Metabolic processes that require many distinct organisms to complete are called what?

Answer 22

Community-level metabolic processes