Lecture 19 Flashcards
How are microbes connected to their physical surroundings?
Microbial communities are affected by changes in:
- temperature
- rainfall/moisture
- pH
- salinity
- etc.
How are microbes connected to climate change?
As the claim the changes, microbes will respond, adapt, and evolve in their surroundings.
What are the 2 interconnected sub cycles that are included in the global carbon cycle?
- Rapid carbon exchange among living organisms (fast cycles).
- Long-tmr cycling of carbon through geological processes (slow cycles).
What are long-term and rapid carbon cycles driven by?
Long-term: plate tectonics, weathering, eroding carbon from mountains - sequestration.
Rapid: living organisms - carbon is moving through different realms on a faster time scale.
What is the role of microbes in the global carbon cycle?
Photosynthetic microorganisms (i.e. phytoplankton) drawdown CO2 from the atmosphere during photosynthesis.
Photosynthesis creates usable carbon for other organisms - creates organic matter that goes to the bottom of the ocean.
Bacteria in the ocean will decompose or eat the organic material produced by phytoplankton - consuming a carbon source = release of CO2 by bacteria.
This is a biological carbon pump.
Why does microbial respiration and decomposition lead to the release of CO2?
Heterotrophs microbes break down organic carbon compounds for cellular growth and energy - gets released by bacteria that consume it.
What is organic matter and where does it come from?
Organic matter is material that has come from a recently living organism.
It includes the remains of organisms, such as plants and animals and their waste products in the environment.
Where does soil organic matter derive from?
Terrestrial environments.
On land almost all organic matter is derived from plants.
Where does marine organic matter derive from?
Marine environments.
In the ocean most organic matter is derived from phytoplankton.
What is a major constituent of organic matter?
Carbon.
What determines the fate of organic matter?
The activity of microorganisms that live in the sediment.
If the carbon is degraded it is released as CO2, but if not it will be buried and sequestered for a long time.
How is bioavailability determined?
By intrinsic chemical properties of the compound - its size and structure.
Size: low molecular wight (most bioavailable), high molecular weight (least bioavailable).
Structure: aliphatic (most bioavailable), highly aromatic (least bioavailable).
It is not always te case (e.g. lignin).
Is bioavailability of organic matter only affected by chemical properties?
No lol.
What is the goal of the novel bioreactor system that probes organic matter degradation?
Monitor respiratory CO2 production and collect it sequentially for carbon isotope analysis.
What can carbon isotopes tell us?
C13 signature: differences in source and where something came from.
C14 signature: tells us the age of something.
Explain the “you are what you eat (and breathe) principle for microbes. How do we apply this idea?
Heterotrophic microbes show similar isotopic signature as carbon sources.
The isotopic carbon respirometer-bioreactor measure and collects CO2 for carbon isotope analyses.
It allows us to track the source, age, and sequences of carbon compounds that are degraded by microorganisms.
For the degradation of most organic matter, what do they require?
The use of extra cellular enzymes.
Extracellular enzyme activity is a key step in organic matter degradation in the ocean.
How do we use genomic characteristic to observe patterns of organic matter degradation?
We can count the total copy number of genes encoding for known extra cellular enzymes.
Organic matter degradation patterns are consistent with genomic characteristics for the two example species. .
Explain the organic matter in the permafrost.
Permafrost contains large stores of organic matter that have been locked for thousands of years.
Microbial organisms are seasonally frozen and preserved within the permafrost.
What is the positive feedback cycles happening in the arctic and what are its consequences?
Positive feedback cycle: less ice and snow causes more warming (less reflection of sun’s radiation) - more warming causes less ice and snow.
Thawing permafrost = microbes are making a shift from dormancy to activity.
When the claim the warms, the microbes become active and degrade organic matter leading to the release f greenhouse gases.
What kind of microbes might become active when permafrost thaws?
Most bacteria release CO2 as a byproduct of their metabolism. Some microorganisms can release methane (more potent).
