Ecology Flashcards
Microbes interact with
Other organisms and their environment
? Carry out the essential activities
Microbes
Species diversity and abundance
Ecology
Ecosystem definition
complex of plants, animals, microbes, abiotic items.
Describe the microbial habitat
Microbes inhabit any plant or animal habitat but also where animals and plants cannot live.
What percent of biomass do microbes account for?
50% and they are ubiquitous (appear everywhere) on the surface and deep within earth.
Know parasitism, mutualism, commensalism
Recite to yourself.
What do the rates of microbial activities depend on?
nutrient availability and growth conditions
What defines a group of microorganisms of the same species living in the same place?
Population
Community
pop. of one species living with one or more species.
Species richness
total number of diff species
Species abundance
proportion of each species in an ecosystem.
Guilds are
metabolically related microbial populations
Niche
habitat shared by a guild that supplies nutrients and conditions for growth.
Biogeochemistry
study of biologically mediated chemical transformations.
What does a biogeochemical cycle define?
the transformations of a key elements by a biological or chemical agent.
Microbes play roles in E transformation and biogeochemical processes that result in
recycling of elements in living systems.
Microenvironment
the immediate environmental surroundings of a microbial cell.
What is the difference between growth of microbes in nature versus the lab
the growth rates in nature are well below maximum growth rates from the lab.
Why are surfaces important?
Nutrients absorb to surfaces and microbial cells can attach to surfaces.
What are the benefits of biofilms
prevent detachment of cells, nutrients for growth, protect from predation or immune system
How to biofilms form>
They attach (polysaccharides), then expression of formation specific gens that encode the proteins to synthesis signaling molecules and initiation matric formation.
What sensing is using in maintaince of a biofilm?
Intercellular communication called guorum sensing.
Name in order the steps of biofilm formation
Attachment, colonization, development, active dispersal.
What microbe causes an issue for medical devices
Psuedomonas aeruginosa (memorize!)’
What are the major intercellular signalling molecules?
acylated homoserine lactones
What do lactones activate
biofilms fformation gene expression
How do biofilms effect industries
Reduce flows in pipes, corrosion, contamination in food/ bev eqipment.
Microbial mats
Thick biofilms, built by phototrophic or chemolithotrophic bacteria.
Chemolithotrophic mats have what type of bacteria?
sulfur-oxidizing bacteria: beggiatoa species
Where do microbial mats like to grow?
where anoxic water is rich in hydrogen sulfide meets oxic water.
Most microbial growth takes place where?
On the surfaces of soil particles.
Soil around plant roots where there is most nutrients is the?
Rhizosphere
What are the limiting nutrients in the soils?
N2, P, H2O
Soils are composed of
Inorganic (40%) organic (5%) air and water (50%) living organisms.
See soil aggregates slide 21
Sand, silt, clay.
Surface soils rely on? Subsurfaces rely on?
Water availability.
Nutrition avilability.
? Exist deep in subsurface
Archae and Bacteria. Use H2 oxidizing or sulfate reducing. See mine picture. 3 KM deep
Balance between ? controls the oxygen and carbon cycles
photosynthesis and respiration.
Phytoplanktons are ? phototrophs while benthic are?
oxygenic phototrophs that are susepnded frely in water while benthic are attached to the bottom or side of lakes!
Activity of heterotrophic micros are dependent on
primary producers
Difference from oxygenic phototrophs and anoxygenic phototrophs
Oxygenic produce organic matter and oxygen
Anoxygenic produce organic matter but NOT oxygen,.
Oxygenic phototrophs are
cyanobacteria and algae
Blooms can occur due to
nutrient (N, P) influxes, eutrophication
Collapse of blooms lead to
oxygen depletion in lower water layers
Oxygen concentrations in aquatic systems are dependent on
the amount of organic matter present and the physical mixing of the system
“Turn over” occurs in ? while stratificatio occurs in?
- fall & spring
- summer
Anaerobic organisms thrive in
lower lake levels during stratification
Rivers are mixed well because of ?
Can still suffer from oxygen deficiencies because of high inputs of
- Rapid water flow
- From organic matter from sewage, and agricultural and industrial pollution.
Biochemical Oxygen Demand (BOD)
Microbial oxygen-consuming capacity of body of water.
Ocean
Saline, cooler, low in nutrients.
Open ocean nutrient levels are
relatively low, esp. at surface
Coastal areas and upwelling areas have higher nutrients
What drives marine ecosystems?
The primary productivity,
Why are nutrients higher at deeper depths?
Recycling by bacterial consumers.
Oceans have lower overall ?
productivity
Eutrophic open ocean areas may lead to
o2 Depletion “dead zone”
Explain deepwater horizon oil spill
Largest marine spill over, bloom of gammaproteobacteria Colwellia, and cycloclasticus.
What could have reduced the impact of the oil spill?
Early growth of hydrocarbon-degrading bacteria
Prochlorococcus is a prokaryotic cyanobacterium that dominates what? Then describe it
Dominates the open ocean.
Very small and can obtain nutrients in low level (surface to volume ratio benefit)
- is greater than 40% of the biomass of marine phototrophs and is 50% of net primary production.
This phototroph fixes nitrogen and puts nutrients in the ecosystem also looks like sawdust on ocean surfaces
Trichodesmium
What dominates higher productivity waters?
Eukaryotic phytoplankton. Diatoms, prymesiophytes, and green/golden algae.
Small planktonic heterotrophic prokaryotes are abundant in what waters?
Pelagic
What happens to prokaryote densities in the open ocean as it goes deeper?
They decrease in depth
10^6 for ? waters
and how much when below 1000 m
10^6 for surface waters and drop to 10^3 - 10^5 below 1000 m.
The most abundant group of bacteria is from what clade?
SAR11 clase. Identified as group based on 16s rRNA sequencing.
Representative genus is palgibacter
Oligotroph
Oligotrophic
grows best at very low nutrient concentrations.
Peligibacter has
small cells/genome.
Proteorhodopsin
allows cells to use light energy to drive ATP synthesis
VERY common ability, does not consider phototrophs.
Explain marine viruses
very abundant, about 10X bacterial count.
mostly bacteriophage
enhance nutrient turnover by lysing so many bacteria.
Explain the microbial loop
DOC/DOM comes from bacteria lysis, dead cells, messy eating by plankton. then the bacteria consume the detritus (detritovores)
who dominates deep sea hydrothermal vents?
chemolithotrophic bacteria. Thermo/hyperthermophiles.
chemolithetrophic prokaryotes utilize inorganic materiasl from the vents.
how are vent communites supported?
based on the PE of reduced chemicals (e-donors)
