Microbes and Energy Flow

Question 1

Describe Natural Environments ‘the unseen majority’

Answer 1

• Most organisms cannot be or have nor been isolated in pure culture
• Identification now down using genetic ‘fingerprints’
• Currently, there are millions of unique 16S rRNA sequences (molecular barcodes) available in databases
• The majority of these gene are therefore from uncultivated bacteria

The uncultured microbial world is far greater than the cultured world

Question 2

Population vs community: microbes

Answer 2

• Individual microbial cells of a species proliferate (increase rapidly) to form a population
• Populations interact/communicate to form communities

Question 3

Define microbial ecology and microbiome

Answer 3

Microbial ecology: the study of the interrelationships among microorganisms and their environment

Microbiome: all microorganisms, and their genes, within a particular environment

Question 4

Describe how the process of breaking bonds can have two potential goals

Answer 4

• Harvesting of building blocks
• Harvesting of energy

This process can run in reverse. You would then need both energy to create a bond, AND a building block to attach to that bond

Question 5

Describe reduction-oxidation in bacteria (RedOx) in terms of the steps the molecules undergo

Answer 5

RedOx is the basis for energy transfer in cells.
- For every action (eg. oxidation) there is an equal and opposite reaction

Step 1.
- H2S is an external electron donor and undergoes oxidation to become S
- NADP+ undergoes reduction at the same time, using the donated electrons to become NADPH2

Step 2:
- NADPH2 undergoes oxidation to become NADP+ again
- CO2 undergoes reduction to produce (CH2O)n using the electrons taken from NADPH2

Question 6

What are the key points of RedOx in bacteria

Answer 6

• Energy harvested from the environment is converted to a ‘local currency’ inside the cell
• NADH/NADPH serve as intermediates to transfer energy inside of cell
• NAD+ and NADH facilitate redox reactions without being consumed; they are recycled
• The RedOx reactions have to be equal and recycling at all times otherwise the cell will die
• A redox reaction is shuttled through NADH/NADPH

Question 7

Describe the trophic nourishment groups in microbiology

Answer 7

FOOD
Autotrophs
- Primary producers
- Fix CO2
- Self sufficient, do not require carbon
Heterotrophs: Get carbon from organic compounds
- Decomposers
- Need fixed carbon, cannot use CO2 directly
- Dependent on primary producers

ENERGY
Phototrophs: Get their energy from light
- use solar energy
Chemotrophs: Get their energy from chemical compounds
- use chemical energy from either C compounds (organic - glucose) or non C compounds (inorganic - H2S)

Question 8

Describe the findings from a microbal mat in a marsh

Answer 8

• Light is the common resource
• Avoid competition by tuning their antenna to different wavelengths
• Different colours in the marsh mat show the different kinda of bacteria in the marsh

Question 9

What can we learn from the cable bacteria

Answer 9

• All organisms need to eat (gather energy)
• If life is present, energy is being harvested from something
• If one source of energy is missing, there must be another one to sustain life. Find it and the communities redox profile will match it