carbon and nitrogen cycles

stages of the nitrogen cycle

nitrogen fixation

nitrification

assimilation

ammonification (decomposition)

dentrificaton

nitrogen fixation

converstion of atmospheric nitrogen into ammonia by nitrogenase enzymes. the microorganisms involved in this are nitrogen fixing organisms such as rhizobium. this provides nitrogen organisms can use

nitrification

oxidaton of ammonia to nitrite using AOB(nitrosomonas) and then oxidizing nitrite to nitrate using NOB (nitrobacter) which plants can then assimilate

assimilation

uptake of ammonium nitrite or nitrate by plants to synthesize organic nitrogen compounds

ammonification (decomposition)

microbial breakdown of organic nitrogen from dead organisms and waste products back into ammonium

denitrification

reduction of nitrate back to nitrogen gas using denitrifying bacteria such as pseudomonas and returning it to the atmosphere which prevents a nitrogen build up

stages of the carbon cycle

photosynthesis respiration decomposition sedimentation combustion

photosynthesis

plants, algae and cyanobacteria convert atmospheric CO2 into organic matter using sunlight

respiration

organisms release CO2 back into the atmosphere by metabolising organic compounds

decomposition

microbes break down dead organic material, releasing carbon back into the soil and atmosphere

sedimentation

over time organic matter can become buried and transformed into fossil fuels

combustion

burning of fossil fuels and biomass releases stored carbon as CO2

microbial roles in the carbon cycle

decomposers

methanogens

methanotrophs

human impact on the carbon cycle

burning fossil fuels

deforestation

farming animals

human impact on the nitrogen cycle

nitrogen-rich fertilizers

burning fossil fuels

livestock farming

Health issues

anammox

ammonium is directly converted into nitrogen gas using nitrite. this is carried out by planctomycetes bacteria. this process removes excess nitrogen from oxygen-limited environments and is used in water treatment plants

DNRA

converts nitrate into ammonium keeping nitrogen in the ecosystem

methanotrophs

bacteria that consume methane and convert it into CO2. found in wetlands, rice fields and landfill sites

intro for carbon cycle

The carbon cycle is important to life on Earth regulating the movement of carbon between the biosphere, atmosphere, hydrosphere, and lithosphere

what is methanogenesis

a microbial process that occurs in anaerobic environments, where microorganisms convert organic matter into methane and carbon dioxide. This process plays a role in global carbon levels and is a step in biogas production.

what is methanogenesis carried out by?

methanogenic archaea which are strictly anaerobic and obtain energy by reducing simple carbon compounds like carbon dioxide, acetate, and methylated compounds.

major pathways of methanogenesis

Hydrogenotrophic methanogenesis

acetolactic methanogenesis

methylotrophic methanogenesis

Hydrogenotrophic methanogenesis

where CO2 is reduced to CH4 using hydrogen (H2) as an electron donor. This process is performed by archaea such as Methanobacterium

Acetolactic methanogenesis

where acetate is cleaved into methane, by archaea like methanosarcina

Methylotrophic methanogenesis

where methylated compounds are converted into CH4 by archaea like methanomethylovorans

what is anaerobic digestion

anaerobic digestion harnesses methanogenesis for biogas production. anaerobic digesters create a controlled environment where organic waste is broken down by microbial communities in the absence of oxygen, producing methane-rich biogas that can be used as a renewable energy

stages of AD

hydrolosis fermentation acetogenesis methanogenesis

what does the nitrogenase enzyme do

it is responsible for biological nitrogen fixation

what are the four features

structure of nitrogenase

nitrogen fixation reaction

oxygen sensitivity

evolutionary conservation