Environmental Biotechnology Flashcards
In wastewater treatment, what are the things we want to remove from the sewage?
- Compounds with high Biological Oxygen Demand (measure of nasty compounds)
- Pathogens
- Human made chemicals (eg. Phenols and Chlorobenzene).
What are the 3 main components of a sewage treatment plant?
Digester, denitrificator and a nitrificator.
What is going on inside a digestor in a sewage treatment plant?
There are acid-forming bacteria and methanogenic archaea inside.
Both are strict anaerobes.
1 - The organic compounds eg. Fats are hydrolysed by enzymes into monomeric compounds eg. Amino acids.
2 - These monomeric compounds then undergo acidogenesis to form higher organic compounds eg. CO2
3 - These undergo methanogenesis to make methane (CH4).
Biogas produced from the reaction is ~70% Methane and ~25% CO2.
What happens in the Denitrificator and the nitrificator?
(Nitrificator) :
- 70% Oxygen is added to ammonia (NH3) to make nitrite (NO2-).
- 20% Oxygen is then added to nitrite to make nitrate (NO3-).
(Denitrificator) :
- 40% Carbon is added to Nitrate to make Nitrite.
- 60% Carbon is then added to Nitrite to make Nitrogen Gas (N2).
Side note - Bacteria use nitrate for respiration.
What is the Anammox process?
It is done by Anammox Bacteria eg. Kuenenia stuttgartiensis.
The process is done inside a compartment called the Anammoxosome.
It allows for an anaerobic process so don’t need oxygen to oxidise Ammonium (NH4+).
Can use nitrite (NO2-) instead of Oxygen.
The anammox process produces less CO2 and lowers operation costs by 90%.
What is Bioremediation?
The use of microorganisms to remediate or eliminate environmental contamination.
Eg. Oil spills.
How are oil spills cleared up?
They usually use the bacteria Alkanivorax borkumensis.
It uses alkane hydrocarbons as substrates so lives exclusively on alkanes.
Fertilisers are often thrown onto the oil spill to speed the process of bioremediation up.
How is bioremediation in soil usually done?
Pseudomonas species are normally used.
Have a lot of benzene ring degradation enzymes.
How is benzene degraded in bacteria?
It is an aerobic process:
Benzene -> catechol
Then either…
Ortho-cleavage pathway (makes acetyl CoA and succinate)
Or
Meta-cleavage pathway (makes acetaldehyde and pyruvic acid)
These products all feed into the Krebs cycle (how bacteria get their energy)
What is a bacteria that can do benzene degradation?
Pseudomonas putida can do both the ortho and the meta cleavage pathways.
On their plasmid (TOL plasmid) they have genes called xyl gene operons which degrade benzene derivatives.
How is toluene (methylbenzene) degraded?
Toluene -> CO2
Geobacter is the most common microorganism used for Toluene degradation.
Iron is reduced from Fe(III) to Fe(II).
It uses iron is it’s terminal e- acceptor.
Azoarcus tolulyticus is another common Tuluene degradator.
It reduces Nitrate instead of Iron.
Can microorganisms recover metal?
Yes.
You can do bioleaching from ores, some accumulate metals and some get rid of toxic metals.
