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39 Cards in this Set

  • Front
  • Back

Microbial ecology

Study of interrelationships between microorganisms and their environments

Ecosystem

Community of organisms and their natural environment



Population

Group of organisms in the same species (same time, same place)

Guild

Metabolically similar organisms that exploit the same resources in the same way

Microbial communities vs communities of macroorganisms

Microbial communities are one population, communities of macroorganisms are several different organisms living together

Freshwater lake ecosystem- Photic Zone

Oxygenic phototrophs

Freshwater lake ecosystem - Oxic zone

Aerobes and facultative aerobes

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

Chemo vs photo

Organism consumes sunlight or chemical matter

Organo vs litho

Organism consumes organic or inorganic matter

Hetro vs auto

Consumes others or creates own energy

Chemotrophy Energy Flow

Electron donor (eg glucose organotroph, NH3, H2, S lithotroph) --> Electron acceptor (O2, NO3, SO4, Fe3, aerobic, CO2 anaerobic)

Chemotrophy Carbon Flow

Carbon source (glucose, organic heterotrph/ CO2 inorganic autotroph) --> Building blocks

More than one type of metabolism

Humans are aerobic but E.coli can be either aerobic or anaerobic through fermentation

Primary producers

Photolithoautotrophs

Important for C, N, S cycling

Chemolithoautotrophs

5 groups of phototrophic bacteria

Cyanobacteria - autotrophic and oxygenic



Others - Purple/ non sulfur, Green/non sulfur, Heliobacterium (anoxygenic)

Objectives

1. Explore biodiversity and interactions of microorganisms in nature


2. Measure microbial activities and monitor effects

Common activities measured

1. Primary production


2. Decomposition


3. Biogeochemical cycling

Habitat

common/ extreme in pH, pressure, salt, anoxygenic


inanimate vs animate

Necessities for growth

Resources, physiochemical conditions

Psychrophiles


Thermophiles


Hyperthermophiles


Halophilic

Cold


Warm


Hot


Salt

Niche

Role, discription, interactions, and habitat of an organism

Microenvironment

Where a microbe lives, physiochemical environments, Winogradsky column

Feast of famine

entry of nutrients into an ecosystem


< quiescence >

Famine adaptions

- accumulate reserves in times of plenty


- high growth rates when possible

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

Biofilm

Community of microorganisms embedded in a matrix of organic polymer (extracellular polymeric substances EPS) adhering to a surface


Contains water tunnels.

Physiochemical gradients

Allows a habitat for microorganisms

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

Dental biofilm

Produced by sucrose contact, stain with iodine,


Iodine + extracellular dextran (EPS)


Streptococcus mutants

Biofilm problems

Pipe clogging


Corrosion



Biofilm uses

-slow sand filtration


-microbial leaching of low grade ores


-vinegar production

Microbial mats

Biofilms of photosynthetic or chemolithotrophic bacteria

Cyanobacterial mats

Complete microbial ecosystems, made up of producers and consumers, found in extreme environments


Green Layer: cyanobacterial, aerobic


Orange Layer: phototrophic, anoxygenic



Negative Interactions

Competition - depends on nutrient uptake and metabolic rates, competitive exclusion possible


Antagonism - Specific inhibitor affecting growth/metabolism

Positive Interactions

Cooperative Interactions - Syntrophy -microorganisms carry out process that neither can do alone


eg) nitrification

Symbiosis ( mutualism vs parasitism)

Relationship between two or more organisms that share an ecosystem


(both benefits, one benefits the other is harmed)


Continuum

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