MICRO CH.28 EXAM5

Sergei Winogradsky

founded field of microbial ecology; global biogeochemical (nutrient) cycles

Winogradsky Column

mimics a natural microbial ecosystem

4 billion years

microorganisms existed

less than 1%

microbes successfully grown in pure culture

Earth BioGenome Project

sequencing microbial genomes allowing for the identification of microbes that we cannot grow in a lab (metagenomics)

Ecology

study of interactions of organisms with one another and the environment

population

Organisms of the same species in a defined area

commmunity

All living things (organisms) in a defined area

ecosystem

All living and non-living things in a defined area

biosphere

All areas on the planet with living things

ecological niche

role an organism plays in the ecosystem

symbiotic relationships

close ecological interaction of organisms; mutualism, commensalism & parasitism

mutualism

both organisms benefit (+,+)

commensalism

One organism benefits, one is unaffected

parasitism

One organism benefits, one is harmed

food chain/ web

Organisms interact in a feeding structure in the ecosystem

trophic lvl

primary producer, primary/secondaryconsumer & tertiary consumer

autotroph (photoautotroph, chemolithoautotrophy)

primary producer

primary consumer

herbivore

secondary consumer

carnivore

top predator

tertiary consumer

fungi & bacteria

decomposers (heterotophs)

microbial mats

biofilm forming that is thick enough to see

Terrestrial habitat

Soil microbes produce valuable chemicals (antibiotics and other pharmaceuticals), some have ability to degrade toxins (bioremediation)

Rhizosphere

zone of soil and roots; Symbiosis between microbes and roots

Common bacterial genus in soil

• Bacillus

• Streptomyces

• Myxobacteria

• Clostridium

• Agrobacterium

• Rhizobium

bacillus

Gram+ rod, endospore former

Streptomyces

Produces several antibiotics

Clostridium

Gram+ rod, anaerobic, endospore former

mycorrhiza

mutualistic association of plant roots and fungi

Biogeochemical cycles

Methane is produced by Methanogens (Archaea). Oxidized in the atmosphere to CO and CO2.

nitrogen cycle

nitorgen fixation & denitrification

Nitrogen fixation

N2 gas in atm. is reduced to ammonia.

Example: Rhizobium bacteria on root nodules of legumes ; symbiotic relat.

Denitrification; nitrogen cycle

Other microbes release N2 (and N2O) back in atm.

- can be used to remove excess nitrogen from wastewater to prevent eutrophication

Winogradsky column

Develops layers of colors corresponding to bacteria with different physiological capabilities

Microbial activities allow life on earth

Capture energy, cycle nutrients, maintain fertile soil, decompose dead organisms and pollutants

overgrowth of algae

eutrophication

Endomycorrhizas

fungi penetrate root cells, grow within them; most common form, associate with herbaceous plants

Ectomycorrhizas

fungi grow around plant cells, form sheath around root; associate with certain trees

phosphorous

mycorrhizas relationship fungi help plants take up

nitrogen fixation

vital to the incorporation of nitrogen into ecosystems; plants can absorb and use

greenhouse gas

denitrification also leads to release of N2O

nitrogen cycle

Nitrogen found in proteins & nucleic acids; Necessary for organismal growth

methanogens

In anaerobic environments, CO2 is used by

hyphal networks

link various plants & Provide plants with a mechanism to share signals

soil habitat

greatest range of biosynthetic and biodegradative capabilities