L10 Microbial Ecology and Elemental Cycling Flashcards
What are the 4 main cycles
Carbon
Nitrogen
Sulfur
Phosphorous
What drives the elemental cycles
Microbes
What are abiotic components contributing to elelmental cycles
Volcanic activity and fires
Weathering of rocks, sedimentation and run off
Gas absorption by oceans
What are biotic components contributing to elemental cycles
Photosynthesis and respiration
Elemental fixation for biomass
Environemtal mediation
What is environmental mediation
Altering the environment either as a consequence of microbial activity e.g. acidification in mine wastes or to alter the local conditions to better suit growth e.g. acidification by fungi, cabinate precipitation by biofilms
How can global warming impact microbial systems
accelerates methane release by methanogens
What was the role of microbes in early earth
Microbes created the atmosphere, built organic molecules of life and started the cycles
What is assimilation
Example
Process of acquiring an element and building biomass
Carbon fixation, absorption of glucose
What is dissimilation
Example
Breakdown of organic molecules into inorganic molecules
Respiration to carbon dioxide
What does metagenomics show us about a community
What species of microbes are oresent and how are they structured
What is the issue with metagenomics
Just because DNA is there it doesnt mean all the species there are active e.g. Spores
What does functional diversity tell us about a microbe community
Determine active processes
easure expressed genes for their function
Measure the products of metabolism
What is a limiting nutrient and what effect do they have on habitat colonisation
Habitat colonisation is regulated by limiting nutrients
The proportion of an available element that is low enough to control the growth - there is enough of all the elements to continue growth except for the limiting nutrient
Often not carbon
What is usually the limiting nutriwnt in aquatic systems
Nitrogen
What effect can addition of nitrogen have to aquatic systems
Give a location where this occurs
Algal blooms
Gulf of Mexico dead zone - run off from farming causes blooms which use up all the resources, heterotrophic bacter use up all the oxygen (hypoxia) so other species cannot survive
Abiotic environmental sources of nutrition (geomicrobiolgy)
Interaction with atmosphere, water and minerals
Autotrophy and lithotrophy
Biotic environmental sources of nurition (biogeochemistry)
Saprotrophy and symbiosis (mutualism, parasitism, pathogens, commenalism)
Heterotrophic and organotrophs
Give an example of when an elemnt may have high abundance but low availability
In forest systems where nitrogen is locked up in fungal cells
Marine systems with low soluble iron availability, most is stored in rocks
What parameters can affect microbial activity
Redox potential (dissolved salts)
Water availability and osmotic pressure
PH
Light
Limiting nutrients
Temperature
Oxygen
Toxic compounds
Interactions with other organisms
What is a source
Part of the biosphere that stores significant quantity of a particular element
What is a sink
Part of the biosphere that can recieve a particular element
What is a reservoir
Major parts of biosphere containing significant amount of a particular element (can be sources and sinks)
Examples of global carbon reservoirs
Atmosphere
Ocean (biomass, organic molecules, inorganic molecules)
Land (biomass, soil, crust, fossil fuel)
What are 2 common pinciples of all priamry producers
Absorb energy from outside the ecosystem
Minerals assimilated into biomass
What are the primary producers in terrestrial systems
Plants (and lichens in some habitats)
What are the primary producers in aquatic environments
Cyanobacteria and algae (other photosynthetic eukaryotes e.g. Diatoms)
What is edaphon
Living soil bacteria
What is humus
Organic colloid, where organic compounds have reached a point of stability - also known as humic acid, water absorbant and good for plant rooting
How much carbon dioxide is in the soil atmosphere compared to then the atmosphere
10 times more carbon dioxide
What else can be found in the soil atmosphere
Transient gases (hydrogen, carbon monixide, methane, hydrogen sulfate) and volatile substances
How much of the originally fixed carbon dioxide makes it to decomposers (fungi, bacteria) from consumers (protists, fungi)
10%
How many species of fungi use nematodes to supplement their nutrition
160
How do fungi trap nematode and recieve nutrition
Circular traps or glue traps (sticky fragments of mycelia)
Fungus penetrates and grows through nematode absorbing nutrition
How can seasonal fluctuations affect wetland soil
Alter oxygen availability
Anaerobic / fermentation when flooded (hydric soil)
Aerobic when not
Where is the littoral zone
Edge of water body
What is the neuston
Air-water interface where a large number of microbes exist
Where is the euphotic (photic) zone
Upper part of water column where light can penetrate for photoautotrophs
Where is the aphotic zone
Fromt he end of the photic zone to the sediment
How do algae and protists stay in the neuston
Use surface tension to ‘hang’ from surface
What metabolic modes exist in the aphotic zone
Heterotrophs and lithotrophs
What is the thermocline
Depth where temperature decreases steeply causing water density to increase
What happens as water density increases
What metabolism peaks
How much organic matter is transferred to benthos
Organic matter settles into a stable unmixed region in the water column
Heterotroph populations peak
Low organic transfer to benthos
What does oligotrophic mean when describing the open ocean
Extremely loe nutrient (iron and nitrogen) and organism concentration
Do coastal waters have higher or lower nutrient content than open ocean
Higher
What is BOD
Biological oxygen demand
How much oxygen is used in a given time period
What happens if pollutants enter pelagic open water
Disruption of whole system, burst of heterotrophic activity
How low does oxygen reach in open oceans
Can reach benthos for lithoautotrophs to use
What is the oxygen minimum zone
Influx of nutrients - coastal currents lifting from below or input from pollution
Where organic molecules reach oxygen creating rapid heterotrophic proliferation
Region depleted of oxygen
What can prolonged pollution cause
Dead zones
What is the main difference between marine and freshwater environments
Salt content
What are the layers of a freshwater lake
Neuston
Epilimnion
Thermocline
Hypolimmnion
Benthos / sediment
What is the epilimnion
Warm, well-mixed oxygenated
Photo and heterotrophy
What are the condition sin the hypolimnion and what survives here
Generally anoxic
Sulphur bacteria
What are the conditions in the benthos of lakes and what microbes are present
Oxygen levels fall rapidly
Anaerobiv respirers
What is the main pollutant of lakes
Nitrogen and phosphorous fertilisers
What effect do fertilisers have on lakes (life cycle of bloom)
Remove limiting nutrients from algae causing a bloom
Blooms die, decomposed by heterotrophs which use up all the oxygen and release carbon dioxide
Creating anoxic environment
How many more microbes are suppored in anoxic eutrophic lakes
What is the drawback
10 times more microbes - anaerobiv phototrophs, fermenters
Cannot suport much animal life
