week 8 Flashcards
Symbiosis? what is typically seen?
- stable association of two or more organisms (host and symbiont), beneficial, neutral or negative impact
- Genomic reduction typical in symbiotic relationships (genome gets very large and will start to cut costs to save energy)
faculitive and obligatory?
Facultative (aid each other - preferable but not required ) or obligatory (entirely independent - required )
mutualism?
- usually obligatory; both partners benefit from each other
coevolution
evolved together - partners cannot grow without each other
what are 4 examples of mutaulaism?
- buchnera aphidicola and aphids - microbes get a secure habitat and the host gets AA absent in the sap
- termites and protists - termites feed on cellulose and lignocellulose (can not digest on their own so protest helps)
- Coral holobiont - protest gives fixed-c for nitrogenous compounds bc worm lacks digestive track to make C
- rumen ecosystem in cows - breaks down plant matter for the cow and gets food/home from cow
cooperation?
- non-obligatory - not needed for survival
what are examples of cooperation?
- nematode and nematophilia - bacteria live inside and kill insects ,and nematode gives home
- fungal highway - hyphae grow toward nutrients and bacteria move along the surface to explore the environment
- Lichens - mycobiont (fungi provide water and minerals) and photobiont (algae/cyanobacteria provides oxygen)
antagonism? three types
- one organism negatively impacts another
1. predation
2. parasitism
3. competition
what is predation? two strategies used?
- killing - benefits after the victim is killed
1. Epibiotic predators - attach to preys surface and lyse to release preys cytoplasmic contents (Vampirous lugosii - sucks contents. & micrococcus xanthus - consumes organic mater from dead organisms )
2. Endnobiotic predators - invade victims’ cytoplasm, where they consume contents to get energy. (bdellovibrio)
Competition? Two possible outcomes?
- uneasy truce between microbes - Different organisms try to acquire the same resources
1. Contact-independent growth inhibition - carried out by secretions of diffusible compounds (antibiotics)
2. Contact-dependent growth inhibition - physical proximity for toxin delivery
parasitism? benfits? gains what?
- exploitation
- Benefits while the victim is alive
- It can involve nutrient acquisition, physical maintenance, or both
syntrophy? example
- when one species benefits from the metabolic products of another
- Example - Methanotrophic archaea grow in association with sulfate-reducing bacteria
– The archaea consume methane and produce by-products that the bacteria use, while the bacteria help the archaea by removing these by-products, benefiting both organisms
what are the two ways bacteria defend themselves against viruses?
- Restriction modification - chemically distinguish viral and host DNA and hydrolyses viral DNA
- CPISPR/Cas system - recognizes viral DNA by comparing samples from previous encounters to identify and degrade viral genomes
what are communities dependent on?
Energy source (nurteint)
Terminal electron acceptor
Sunlight
what state does water exist in? what are they considered as?
- dissolved
- Microbial versatility = consumption/use of variety of molecules
carbon cycle ? what can it be reduced into? found where? release off? fraction ? global?
- carbon is continuously transferred from one to another
- Plants and microbes fix CO2
- CO2 can be reduced anaerobically to methane, which itself can be oxidized
- Methane can be found in rice paddies, coal mines, etc
- Release of CO2 and biomass production
- A small fraction of decomposed plant material remains in the soil as SOM
- Balancing global CO2 levels, minimizes climate change
nitrogen cycle: Nitrogen fixation? carried out by? ratio? affects?
- reduction of inorganic N2 to organic form (ammonia)
- Carried out by some bacteria and archaea
- It can be carried out under both oxic and anoxic conditions
- Carbon to nitrogen ratio is important for soil quality
- It affects plant growth, microbial activity, and decomposition
Denitrification
nitrate to nitrogen gas
retunes nitrogen to the atmosphere
N availability in ecosystems -> plant growth and agricultural
phosphorus cycle
required in? excess released in? moves to? nutrints?
- Phosphorus is required for ATP, nucleic acids, lipids, and polysaccharides.
- Commonly short supply in soils dependent on soil pH
- When the soil has bound all phosphorus, the excess is released by soil erosion
- Moves to lakes, streams, and estuaries where it can stimulate the growth of microorganisms
- Nutreninet availability and microbes in soil and water
- Binding to soil depend on soil pH
sulfur cycle
reduction?
depending on?
?->?
- Reduction of sulfate for use in amino acids and protein biosynthesis
- depending on the oxidation of Sulfur species, it can serve as electron donors and acceptors or both
SO4^2- -> H2S in anaerobic (dissimilatory sulfate reduction)
iron cycle
- used in?
- important for?
- element ?
- avalibility for?
- respiration/photosynthesis
- Fe3+ can serve as a terminal electron acceptor during anaerobic respiration in a range of bacteria and archaea (redox reaction)
- Iron availability to plants and algae
maganese cycle
Mn2+ as an electron donor —- reduction(anoxic) ——> MnO2 e- acceptor
<—– oxidation (oxic)
mercury cycle
biomagnifcation?
reduction?
does?
- Biomagnification - anaerobic bacteria feed into the food chain and accumulate
- Demethylation of methylmercury -> Hg^0/reduction
- Microbes can either facilitate toxic transformations or detoxify mercury/preventution of bioaccumilation
Greenhouse gases?
- trapped heat reflected from earths surface in the atmosphere, rather than allowing it to radiate into space
- Gases accumulate if the rate they enter the atmosphere exceeds the rate by which the natural carbon and nitrogen cycle can remove them
What are the consequences of disrupting carbon and nitrogen cycel?
Global climate change
Surface temperature on land and sea and in the atmosphere
Rates of precipitation
Frequency of extreme weather
Phototrophs -
Chemotroph -
Lithotrophs -
Organitrophs -
Heterotrophs -
autotroph s -
Phototrophs - light
Chemotroph - chemicals
Lithotrophs - inorganic
Organitrophs - organic
Heterotrophs - carbon
autotroph s - CO2
What is an axenic culture?
- pure culture that helps scientist understand microbio
What is the great plate count anomaly?
- discrepancy between the number of microbial cells observed by microscopic examination and number of colonies cultivated from same natural sample
what percentage of microbes can be grown in a lab? and why that much?
- 1-5%
- slow growing
- low abundance
- inhibition by other microbes in a mixed culture
- fastidious growth requirements
- cross-feeding or communication signals from other microbes are needed
- lack trigger for growth or exist from a dormant state
What is an enrichment culture?
- promoted growth or a microbe that had been restricted before
- inhibits the growth of other microbes
- misy understand the specific niche microbes inhabit
- know features that set microbes apart
What are the four ways we can investigate macro and micro diversity in a natural community?
- Species richness - the number of different species in the environment
- Population - a group of microorganisms within a single species
- Guild - a group of microbes defined by physiological activity
- Microbial community - microorganisms that share a common habitat
oceanography and limnology
Oceanography - the study of marine systems and related biological, geographical and chemical factors
Limnology - investigations of aquatic systems within continental boundaries
What are important physical factors in water?
Temperature
pH
Light penetration
Osmotic conditions
Dissolved oxygen
Water potential
what effect does solar radiation have on water? Thermocline? Photic zone? Phytoplankton? nutrients?
- Warm water is less dense than cool water
- As water layers mix, nutrients swell up
- Thermocline - warm water floating on top of cooler water
- Photic zone - Upper 100 meters of the open ocean
- A diverse collection of microbes
- Phytoplankton - a major source of organic matter
- Nutrient levels are extremely low
What is the ocean adapted to ?
nutrient liimitation
what is the purpose of the microbial loop?
- key to surviving in the photic zone
1. Recycling of nutrients rather than letting them sink to the seafloor
2. Heterotrophic microbes consume dissolved organic matter (DOM) released by resident microbes
3. Particulate organic matter (POM) - microbial cells, insoluble detritus and other solid organic matter
4. Marine snow is a shower of organic material falling from upper waters to the deep ocean
what happens when CO2 is high in the ocean? what role do viruses have in water?
- If CO2 is high, microbial growth in open ocean that is limited by nitrogen
- Viruses are important members of marine and freshwater microbial communities
- Virus-like particles (VLPs) are now recognized as the most abundant microbes on earth
pelagic and benthic zone
Pelagic - upper layers of water
Benthic = bottom of a body of water
- the microbes here are very slow - doubling times a hundred years
Lotic systems vs Lentic
Lotic systems - free-running waters (streams and rivers)
Lentic systems - free-standing waters (ponds, lakes, marshes, and slow-moving rivers)
what are the two types of lentic systems?
- Dominated by planktonic microbes and invertebrates
1. Oligotrophic lakes - mountain lakes fed from infertile land - why lakes tend to be clear
2. Eutrophic lakes - low-level lakes that catch water from fertile, cultivated soils
High level of planktonic growth - appear turbid
rainfall? mineral soil? Organic soil?
- Well aggregate soil changed to isolated pockets of water
Waterlogged soils can become anoxic
Gas fluxes can change CO2 concentration - Contains less than 20% organic carbon
Most of earths soil is in this category - Possess at least 20% organic carbon
Soil organic matter (SOM)
Retains nutrients and water
Maintain soil structure
what are esturaies ?
- This is where the river (freshwater) meets the sea (saltwater). These are likely to be halotolerant.
- Planktonic microbes and invertebrates dominate microbes in lakes.
what are the three roles microbes have in soil?
Provide nutrients for other organisms
Promotion of plant growth
Associative nitrogen fixation
in the subsurface zones they have microbial processes, what are they:
- shallow subsurface
- regions where organic matter has been transformed by chemical and biological processes to yield Coal, oil, and gas
- zones where methane is made as a result of microbial activity
- energy-starved deep biosphere
What are the main characteristics of a deep hot biosphere?
- bacteria and archaea living in biofilms km below earth’s crust
- genomic studies suggest pthe resence of N2 fixation and denitrification from subterranean nitrogen cycle
