Lecture 3: Ecophysiology

Question 1

Draw a bacterial growth curve.

Answer 1

Question 2

What is microbial autecology?

Answer 2

The study of (micro)organisms in their environment

Question 3

What is the unit of measure for macroeukaryotes vs microbes?

Answer 3

Individual vs. populations

Question 4

Which of the following would limit growth or survival of microbes in nature?

A. Reduced levels of nitrogen
B. The presence of other microbes
C. An increase in temperature
D. Both A and C
E. All of the above

Answer 4

A. Reduced levels of nitrogen
B. The presence of other microbes
C. An increase in temperature
D. Both A and C
E. All of the above

Question 5

List the abiotic factors that affect environmental conditions.

Answer 5

• Temperature: -20ºC - 121ºC
• pH: <0 - 13
• Pressure: 1 atm (sea level) - 1400 atm (deep sea)
• Salinity: distilled water - >30%
• Oxidation state: Eh scale
• UV irradiance

Question 6

Explain Shelford’s Law of Tolerance.

Answer 6

Environmental parameters determine the abundance and distribution of organisms
- Averages over time
- Interactivity across conditions
- Differences in lab and field

Question 7

What is acclimation vs. adaptation?

Answer 7

• Acclimation is temporary (ceratium growing “fingers” to catch more light)
• Adaptation is permanent (change to genome)

Question 8

Compare psychrophiles vs. psychotolerant vs. thermophiles.

Answer 8

• Psychophiles: optimal growth temp is <15ºC
• Psychotolerant: optimal growth temp is >20ºC, but will grow <10ºC
• Thermophiles: no growth below 50ºC

Question 9

What do steno- and eury- describe?

Answer 9

Tolerance windows

Question 10

What do steno- and eury- mean?

Answer 10

• Steno: narrow
• Eury: broad

Question 11

What is microbial synecology?

Answer 11

The study of the interaction of populations with each other

Question 12

What mediates microbial synecology?

Answer 12

Resources
- Subject to competition and consumption
- Biological interactions

Question 13

Name some resources that mediate microbial synecology.

Answer 13

• Space: habitat
• Oxygen
• Water
• Other inorganics
• Nutrients
• Visible irradiance

Question 14

What is Liebig’s Law of the Minimum?

Answer 14

Limiting nutrients determine microbial growth/biomass

Question 15

What is the Redfield ratio?

Answer 15

106 C:16 N:1 P

Question 16

_____ is a limiting nutrient for phytoplankton growth.

Answer 16

Iron

Question 17

How do microbes deal with the typically low nutrient availability in the environment?

Answer 17

They adapt to low vs. high carbon

Question 18

What is the Scout Hypothesis?

Answer 18

Dormant microbial cells wake up into active “scout” cells stochastically, independently of environmental cues

Question 19

Fill in the culturable vs. VBNC chart.

Answer 19

Question 20

What are the 3 inorganic nutrient scavenging systems?

Answer 20

1. Siderophores: extracellular iron chelators, solubilizers
2. Alkaline phosphatases: scavage organic phosphate
3. Nitrogenases: fix N₂ only under combined nitrogen depletion

Question 21

What resistance structures do bacteria form?

Answer 21

• Endospores
• Cysts
• Akinetes

Question 22

Endospores can resist _____, _____, _____, _____, and _____.

Answer 22

• UV
• Desiccation
• High temps
• Low temps
• Chemicals

Question 23

What are akinetes?

Answer 23

Thick-walled, non-motile dormant cells

Question 24

Why is motility important for microbes?

Answer 24

Due to small size, microbes often rely on diffusion to get nutrients
- Have to move toward the nutrients

Question 25

What are chemo- and phototaxis?

Answer 25

Biochemical sensing of the environment
- Two-component signal transduction regulatory systems

Question 26

Oligotrophs are ____ carbon while copiotrophs are _____ carbon.

Answer 26

1. low
2. high