Lecture 19 Microbes in The Environment

Question 1

Define microbial ecology

Answer 1

Interactions between microbes and the environment as well other microbes and themselves

Question 2

How do microbes interact with the environment? What are the mechanisms?

Answer 2

1. two component regulatory system
2. taxes
3. endospore formation
4. quorum sequencing

Question 3

What enables physiological changes in response to environmental changes in microbes?

Answer 3

Two component regulatory system

Question 4

HOW do two component regulatory system enable physiological changes in response to environmental changes in microbes?

Answer 4

link external conditions with intracellular gene expression.

1. sensory kinase
2. regulatory receptor

sensory kinase autophosphorylates when sensor domain detects environmental change (chemotaxi help identify this)

then transferred to regulatory receptor which has changed conformation affecting their future interactions.

Question 5

Define chemotaxis

Answer 5

They transmit information to 2 component systems.

respond to diverse environmental cues

Question 6

how are chemotaxis related to flagellar rotation?

Answer 6

chemoreceptors transmit environmental information to a two-component regulatory system, influencing the rotation of flagella for movement towards attractants or away from repellents.

Question 7

How does flagellar motility work?

Answer 7

Flagella is the motor
MS and C ring are the rotor
motA and motB create a channel for proton flow which induces rotation of the flagella.
PMF is the fuel for the motor

Question 8

What are endospores, and why are they important?

Answer 8

Highly resistant structures (formed by G+)
Important for survival in unfavourable conditions due to their resistance to heat, radiation, and chemicals.

Question 9

List the different modes of swimming motility

Answer 9

run and tumble
run stop
run reverse flick

Question 10

Signal transduction in E.coli:

What does the methylation level of MCP (methyl-accepting chemotaxi proteins) do?

Answer 10

Enable the cell to detect whether it’s moving towards or away from the attractants.

Question 11

When does sporulation typically occur?

Answer 11

occurs in response to environment stressors (nutrition depletion, dessication…)

Question 12

Describe the process of Endospore germination

Answer 12

1. activation
2. germination triggered by stimuli
3. subsequent outgrowth.

Enzymes become active, and the spore returns to a vegetative state.

Question 13

How is sporulation regulated at the molecular level?

Answer 13

By a phosphorelay system involving sensor kinases and alternate sigma factors.

5 sensor kinases that detect signals that trigger sporulation.

Question 14

What is quorum sensing, and what molecules are involved?

Answer 14

cell-to-cell communication in microbes

detection of cell density and environmental flow using small molecules.

-acyl homo-serine lactone; interspecific communication
-autoinducing peptides; intraspecific
-auto inducer 2; universal