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39 Cards in this Set
- Front
- Back
Microbial ecology |
Study of interrelationships between microorganisms and their environments |
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Ecosystem |
Community of organisms and their natural environment |
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Population |
Group of organisms in the same species (same time, same place) |
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Guild |
Metabolically similar organisms that exploit the same resources in the same way |
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Microbial communities vs communities of macroorganisms |
Microbial communities are one population, communities of macroorganisms are several different organisms living together |
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Freshwater lake ecosystem- Photic Zone |
Oxygenic phototrophs |
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Freshwater lake ecosystem - Oxic zone |
Aerobes and facultative aerobes |
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Freshwater lake ecosystem - Anoxic sediments |
Guild 1; denitrifying bacteria, ferric iron- reducing bacteria Guild 2; sulfate- reducing bacteria, sulfur- reducing bacteria Guild 3; fermentative bacteria Guild 4; methanogens, acetogens |
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Chemo vs photo |
Organism consumes sunlight or chemical matter |
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Organo vs litho |
Organism consumes organic or inorganic matter |
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Hetro vs auto |
Consumes others or creates own energy |
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Chemotrophy Energy Flow |
Electron donor (eg glucose organotroph, NH3, H2, S lithotroph) --> Electron acceptor (O2, NO3, SO4, Fe3, aerobic, CO2 anaerobic) |
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Chemotrophy Carbon Flow |
Carbon source (glucose, organic heterotrph/ CO2 inorganic autotroph) --> Building blocks |
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More than one type of metabolism |
Humans are aerobic but E.coli can be either aerobic or anaerobic through fermentation |
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Primary producers |
Photolithoautotrophs |
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Important for C, N, S cycling |
Chemolithoautotrophs |
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5 groups of phototrophic bacteria |
Cyanobacteria - autotrophic and oxygenic
Others - Purple/ non sulfur, Green/non sulfur, Heliobacterium (anoxygenic) |
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Objectives |
1. Explore biodiversity and interactions of microorganisms in nature 2. Measure microbial activities and monitor effects |
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Common activities measured |
1. Primary production 2. Decomposition 3. Biogeochemical cycling |
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Habitat |
common/ extreme in pH, pressure, salt, anoxygenic inanimate vs animate |
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Necessities for growth |
Resources, physiochemical conditions |
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Psychrophiles Thermophiles Hyperthermophiles Halophilic |
Cold Warm Hot Salt |
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Niche |
Role, discription, interactions, and habitat of an organism |
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Microenvironment |
Where a microbe lives, physiochemical environments, Winogradsky column |
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Feast of famine |
entry of nutrients into an ecosystem < quiescence > |
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Famine adaptions |
- accumulate reserves in times of plenty - high growth rates when possible |
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Lab results are different that nature Distribution of resources are non uniform Microbial mono-cultures are rare |
Lab conditions allow bacteria to grow faster Soil underlying a dead animal Competition is fierce |
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Biofilm |
Community of microorganisms embedded in a matrix of organic polymer (extracellular polymeric substances EPS) adhering to a surface Contains water tunnels. |
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Physiochemical gradients |
Allows a habitat for microorganisms |
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Biofilm Advantages Disadvantages |
A: Protection from toxicants, predators, immune system cells, ability to remain withing a favorable niche, nutrient tapping D: Highly competitive, localized biomass can be efficiently preyed upon, infected by viruses |
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Dental biofilm |
Produced by sucrose contact, stain with iodine, Iodine + extracellular dextran (EPS) Streptococcus mutants |
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Biofilm problems |
Pipe clogging Corrosion |
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Biofilm uses |
-slow sand filtration -microbial leaching of low grade ores -vinegar production |
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Microbial mats |
Biofilms of photosynthetic or chemolithotrophic bacteria |
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Cyanobacterial mats |
Complete microbial ecosystems, made up of producers and consumers, found in extreme environments Green Layer: cyanobacterial, aerobic Orange Layer: phototrophic, anoxygenic |
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Negative Interactions |
Competition - depends on nutrient uptake and metabolic rates, competitive exclusion possible Antagonism - Specific inhibitor affecting growth/metabolism |
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Positive Interactions |
Cooperative Interactions - Syntrophy -microorganisms carry out process that neither can do alone eg) nitrification |
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Symbiosis ( mutualism vs parasitism) |
Relationship between two or more organisms that share an ecosystem (both benefits, one benefits the other is harmed) Continuum |
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Ecoli Symbiosis |
Mutualistic - they get environments, you get vit k Commensal - can obtain k elsewhere in the body Parasitic- can cause disease if reaches body tissue |