(12-32) Applied Microbiology Flashcards
1. Define the following terms: Microbial ecology, Community, Ecosystem 2. Differentiate among nitrification, denitrification, and nitrogen fixation. 3. Describe nitrogen fixation and explain its importance. 4. Explain the significance of rhizobia 5. Describe the effects of nutrient-rich runoff on water. 6. Describe what occurs in the nitrogen cycle. 7. Distinguish between oligotrophic and eutrophic waters. 8. Define biochemical oxygen demand (BOD) and explain its significance in wastewate
Define Ecology.
Ecology is study of relationships of organisms to each other and environment
Define Community.
Organisms in given area are termed a community
Define ecosystem.
Communities interact with each other and non-living environment - forms an ecosystem.
Give 8 examples of ecosystems.
- Oceans
- rivers
- lakes
- deserts
- marshes
- grasslands
- forests
- tundra
What type of organism plays a major role in most ecosystems?
Microorganisms.
Earth’s atmosphere has lots of N2 gas, so why can’t plants use it?
N2 contains a triple bond, which is extremely stable and requires a lot of energy to break.
What do swome species of bacteria have that allows them to convert N2 into a useable form, and what is the process called?
- enzymes (nitrogenase)
2. nitrogen fixation
What is nitrogenase strongly inhibited by, and how does that relate to the type of bacteria that fix nitrogen?
- Nitrogenase is strongly inhibited by oxygen.
2. Many N fixers are anaerobes.
What do nitrogen-fixing bacteria convert N2 to?
Nitrogen-fixing bacteria convert N2 to ammonia (NH3).
How many bacterial groups fix nitrogen. Give 3 examples.
- Several bacterial groups fix nitrogen
2. Ex. cyanobacteria, free-living soil bacteria, and nitrogen fixers that live in close association with plant roots.
What do soil bacteria called nitrifiers do? What is the process called?
- Soil bacteria called nitrifiers oxidize ammonia to nitrate (NO3–).
- Called nitrification.
What are microorganisms associated with plants in the legume family called?
Rhizobia
Is Rhizobium aerobic, or anaerobic? Is that a problem, and if so, why?
- Rhizobium is aerobic.
2. Nitrogenase is strongly inhibited by oxygen.
Rhizobia are aerobic and Nitrogenase is strongly inhibited by oxygen. How do Rhizobia deal with that challenge?
Rhizobia produce nod factors, which cause the roots of their plants to develop nodules.
Within a root nodule, low O2 concentration is maintained, which can support respiration but not inhibit the enzyme.
