Define bioremediation, what is it based on and what does it involve
Current and potential use of microorganisms and plants to treat pollution in the environment
Based on natural ability of living organisms to reduce or eliminate pollution
Involves ENHANCING removal rates of pollutants from an ecosystem
Define pollution
the presence in or introduction into environment of harmful or poisonous substances, or excessive levels of light, noise, organic waste etc. Especially as result of human activity
Give 3 broad examples of different types of pollution
Oil spills e.g. Exxon valdez spill. 260000-750,000 crude oil barrels spilled
Atmospheric pollution - anything discharged from chimneys
Contaminated land
What are the 4 classifications of pollutants
Solid
Liquid
Gas
Ionising radiations and electromagnetic waves
What environments are affected by pollution
ALL Marine terrestrial fresh water atmosphere extraterrestrial
What has been the UK’s biggest ‘serious pollution incident’ other than ‘other’ on the pie chart since 2008
sewage and waste
What are the challenges faced when quanitfying pollution in an area?
There’s no true record
325000 sites have had KNOWN use that COULD have led to contamination
Historically still being effected - e.g. lead poisoning of ground by romans
What are the 2 main reasons/arguments for treating pollution
Ecological - destruction of habitat by pollution can lead to losses in species diversity and extinction
Human - pollution can have deleterious effects on both human health and welfare (contaminated land worth less)
What are the 3 broad ways of treating pollution
Physical - use mechanical process e.g. containment
Chemical - e.g. neutralising acid
Often combined to a physiochemical treatment
Biological
Define biological treatment
Any process where a pollutant is converted into an alternative (usually less harmful) form by the action of a biological system.
What aspect of biological agents does bio treatment exploit?
Their metabolic abilities to remove/treat pollutants naturally
Give an historic example of bio treatment
manure on fields as fertiliser
What kind of organisms are used in bio treatment
Animals, plants and microorganisms
Are animals well suited to treat pollution? Why?
Give an example where they have been used
No Large slow growing ethical issues chicken feathers to mop up oil
What is phytoremediation
The use of plants to treat pollution
List the 6 different phytoremediation processes that can be exploited, giving a small description
Phytoextraction-plants translocate pollutant from soil to harvestable body
Phytodegradation-metabolic abilities of plants and associated microorganisms to degrade organic pollutants
Rhizofiltration-plant roots absorb/adsorb pollutants, mainly metals, from water. Then keep them in place
Phytostabilisation-plants reduce bioavailability of pollutants in the environment , by storing them in their plant system
Phytovolatillisation - volatile products taken up with H2O then evaporated, so pollutants are volatised
Rhizodegradation - plant acts as host fro pollutant degrading organism
Give a detailed example of phytoremediation using arabidopsis
Novel cytochrom P450 in a bacteria (R. rhodochrous) that degrades RDX-a high explosive
Transfered gene to arabidopsis, they then express.
Grew plants on contaminated soil - found that it removes and degrades the explosive from soil
What do majority of bio treatments use
microbes - bacteria, fungi, protozoa and algae
NOT viruses
What are the characteristics that make microorganisms suitable for use in waste and pollution treatment
- Ability to survive hostile envir.
- rapid growth rates
- ability to grow on range of C and energy sources
- genetic plasticity - easy for them or us to transfer genetic info
- easy to control and study
- no ethical considerations
What are the 2 basic bioremediation strategies, and define them
Biostimulation - modify conditions to stimulate INDIGINOUS microbe activity to break down pollutant. Can be done both in and ex situ
Bioaugmentation - introduce large quantities bacteria into contaminated environment to remove pollution.
Define in situ and ex situ
ex situ - remove contaminat to specialised treatment facility and treat it there
in situ - treat at site
How is biostimulation done ex situ
In suspended growth reactor
How is biostimulation done in situ
Liquid delivery - add nutirents and/or o2 to site, set up circulatory system so product can be removed
Why does biostimulation not always work
pollutant killed indiginous popl.
What are the 2 options for providing microbes for use in bioaugmentation
grow up indiginous or naturally occuring and inoculate site
develop genetically modified bacteria
What does gene introduction exploit
plasmids, mating of donor and recipient microbes
Can gene introduction occur naturally as well as artificially
yes.
What’s an alternative to natural gene introduction
genes cloned into broad host range plasmid , then optimised via:
transcription, promotor, terminator manipulation
increase copies of plasmid present
improve stability
What is the main porblem with gene stability and how might it be solved
- risk of transfer to other bacteria
- incorporate gene into host genome
Give an example of gene introduction
Phenyl hydroxylase genes from Cornamonas testoseroni R5 (a bacteria with good phenol degrading ability, but not good at surviving outside the lab)
Genes put in rN7 cornamonas that was dominant in sewage sludge
Resulting bacteria were able to survive and degrade pheno 3xfaster than before
How is gene alteration done
Gene cloned in lab bacteria so easier to use
position accordingly with transcription pormotor and terinator regions
increase the number of copies of genes in host
improve stability of cloned gene proteins
Give example of gene alteration
Pseudomonas putida contains pWWO plasmid, whcih allows it to degrade toleune and xylene, byt not ethylbenzoate. DESPITE the presence of all the functional genes needed to degrade it (because EB doesn’t induce the pathway)
Cloned xylS gene (controls pathway) into ecoli and generated mutant that responds to EB
mutant gene transfered to Ps.putida - success
What problems might arise in the real environment even after successful gene manipulation
fail to adapt to contaminated environement conditions
Insufficent substrate
competition with indiginous popl
use other oragnic substrates in preferences to pollutants
predation, usually by protozoa
How could you get around the ‘real environment’ problems
Horizontal gene transfer
Define horizontal gene transfer
introduction of remediation genes into indigious microbes alrewady adapted to survive to that environement
In HGT how is the host strain got rid of once it’s inserted the genes to the indiginous microbe
insert conditional suicide gene to donors
-if the conatminent is not present host dies
Give an example of a conditional suicide system
In presence of inducer contaminent, 3-methylbenzoate, production of lacI repressor blocks Gef protein
When contaminent completely degraded, Gef protein is produced which kills cells by producing porins that destabilise cell membrane
List molecular techniques used to measure what microbes are doing
16s rDNA PCR Reverse transcription PCR Real time PCR Fluorescent in situ hybridization Microarrays reporter genes