Lecture 15 -Bioremediation Flashcards Preview

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Flashcards in Lecture 15 -Bioremediation Deck (38):

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

Ionising radiations and electromagnetic waves


What environments are affected by pollution

fresh water


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


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

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



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
reporter genes