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
