Microbiology: Module 10

an ecosystem

A community of organisms interacting with each other and with their physical environment.

Primary Production

The production of organic molecules from CO₂ using an energy source.

Examples:

• Photosynthesis

• Chemosynthesis

Decomposition

The breakdown of dead organisms and organic matter into simpler substances, recycling nutrients back into the environment

cyanobacteria

Which microorganisms were responsible for the initial rise of oxygen in Earth's atmosphere?

Nutrient Cycling

The movement and recycling of elements between organisms and the environment.

Chemolithotrophic bacteria

What type of microorganisms support hydrothermal vent ecosystems?

chemolithotrophs

Organisms that obtain energy by oxidizing inorganic chemicals

Sulfur compounds

What energy source do chemolithotrophs bacteria use?

They are primary producers

What role do chemolithotrophs bacteria play?

Because energy comes from chemical compounds, not light

Why don't hydrothermal vent ecosystems depend on sunlight?

Carbon Cycle

Microorganisms recycle carbon through photosynthesis, respiration, and decomposition

Nitrogen Cycle

Microorganisms convert nitrogen into different forms through nitrogen fixation, nitrification, ammonification, and denitrification.

Sulfur Cycle

Microorganisms oxidize and reduce sulfur compounds, recycling sulfur between living organisms and the environment.

Iron Cycle

Microorganisms oxidize and reduce iron, making it available for biological processes.

Phosphorus Cycle

Microorganisms help release phosphorus from organic matter and recycle it for plant and microbial growth.

• Anoxygenic photosynthesis

• Nitrogen fixation

• Methanogenesis

Which processes are found only in prokaryotes?

Methanogenesis

The production of methane (CH₄) by certain Archaea

Methanococcus

Name a genus that is an example for Methanogenesis

Methanogenesis

◦ Can use CO2 as a final electron acceptor or other species ferment acetate to

produce methane

◦ Typically an anaerobic process

◦ Decay of organic material (swamp gas), methane in ruminant animals

nitrogen fixation

reduction of atmospheric nitrogen to ammonia

• reduction catalyzed by the enzyme nitrogenase

• very energy intensive (16 ATPs per N2)

• complex enzyme with Mo and Fe, sensitive to oxygen

• Performed only by some prokaryotes.

Azotobacter

Nitrogen Fixating Example by free-living bacteria

Bradyhizobium-legumes

Nitrogen Fixating Example by bacterial-plant symbiosis

Anabaena

Nitrogen Fixating Example by cyanobacteria

Symbiotic Nitrogen Fixation

Nitrogen fixation carried out by bacteria living in association with plant roots (especially legumes)

Heterocysts

Specialized cells in some cyanobacteria where nitrogen fixation occurs

Unique Biodegradations

The ability of prokaryotes to break down environmental pollutants and complex compounds.

• Breakdown of hydrocarbons (oil spills)

• Degradation of benzene

• Degradation of toluene

Unique Biodegradations examples

Chromatium

Name a genus of Anaerobic photosynthesis

Prochlorococcus

Name a genus of Aerobic photosynthesis

Azotobacter

Name a genus of Free-living bacterial cell nitrogen fixation

Anabaena

Name a genus of Cyanobacterium with heterocysts

Rhizobium

Name a genus of Bacterium fixing nitrogen in plant root nodules

Pseudomonas

Name a genus of Denitrification

Thiobacillus

Name a genus of Sulfur oxidation

Beggiatoa

Name a genus of Sulfur oxidation

Desulfovibrio

Name a genus of Sulfate reduction

Methanobacterium

Name a genus of Methanogenesis