Bioremediation

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Bioremediation
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Bioremediation

• Process by which microorganisms act to degrade
  hazardous contaminants
• Certain microorganisms can digest fuels and
  solvents, or other substances that are hazardous
  to humans
• Breaks contaminants into less harmful substances,
  primarily carbon dioxide and water

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Bioremediation Requirements

• Three Factors
• Type of organisms present
• Site conditions
• Quantity and toxicity of contaminant chemicals

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Sub-optimal Conditions

• For conditions that are inadequate, improvements
  can be made
• Pumping air
• Adding nutrients
• Adding fertilizers
• Adding microorganisms from other locations
  (bioaugmentation)

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Where does this take place?

• Aerobic and anaerobic conditions of
• Soil
• Water
• Subsurface materials
• Residues and sludge
• In situ and ex situ

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In Situ
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Ex Situ
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Importance

• Gateway to future waste clean-up possibilities
• Non-lethal weaponry
• Enhance environmental quality

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Acclimation

• A period when no remediation appears to be
  occurring (lag phase)
• Concentration of contaminants remains stable
  until microbial population is large enough to
  begin degradation
• Great importance to human and environmental
  health, and must be considered when
  bioremediation techniques are being used

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Acclimation

• Chemical Environment Length of Phase
• Chlorinated Biofilm 10 days-5 months
• benzenes
• PCP Stream Water 21-35 days
• Several
• aromatics Soil 10-30 hours

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Acclimation

• Is affected by several factors
• small populations
• presence of toxins
• predation of biodegrading organisms
• diauxie

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Areas of Remediation

• Pesticides
• Petroleum spills
• Anti-material
• Radiation

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Pesticide Bioremediation

• Organophosphates
• Carbamates
• Pyrethroids

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Organophosphates

• Some of the most toxic chemicals used in
  agriculture
• Agrobacterium is a bacteria that metabolizes
  these compounds
• Attacks the bonds and breaks the compound into
  less harmful constituents
• Predicted to degrade 90 of organophosphate
  compounds

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Pyrethroids

• Synthesized from petroleum derivatives
• Mimic botanical pyrethrins
• One of the least acutely toxic chemicals to
  mammals
• Quickly deactivated by metabolic processes such
  as hydrolase enzymes

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Carbamates

• Insecticide derived from carbamic acid
• Widely used in homes, gardens, and agriculture
• Broken down by bacteria enzymes that degrade the
  carbamate insecticide carbaryl

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Petroleum Spills

• Most common situation using bioremediation
• Bioremediation of Petroleum was successfully
  executed in March 1989 during the Exxon-Valdez
  Oil spill
• Aromatic hydrocarbons broken down by
• Cyanobacteria and organotrophic bacteria
• Phormidium corium
• Pseudomonas spp.

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• Sand bank in channel Oct 1991?
• Oil disappears from intertidal zone
• April 1993?

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Radiation

• Radioactive materials cannot be destroyed, but
  microbes may facilitate their immobilization
• Changing form and activity of radionuclides
• Change of oxidation state
• Ex. microbial reduction and immobilization of
  Uranium in Fe(III) and Mn(IV) can occur in
  sediments

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Radiation

• Deinococcus radiodurans (D.radiodurans)
• strange berry that withstands radiation
• Most radiation resistant organism known
• 10 Gy is sufficient to kill a human, 60 Gy will
  kill E.coli
• (Gy or gray is the adsorption of one joule of
  radiation energy by one kilogram of matter)
• D.radiodurans withstands an instantaneous does of
  5,000 Gy without loss of viability, and 15,000 Gy
  with 37 viability
• Can survive cold, heat, dehydration, vacuum, and
  acid

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Radiation

• D.radiodurans survival characteristics
• Rapid repair of damaged chromosomes (12-24 hours)
• Contains multiple copies of its own genome
• Cell wall with three or more layers and a thick
  peptidoglycan layer

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D.radiodurans

• Idea is to genetically incorporate into this
  microbe enzymes that will enable it to metabolize
  heavy metals such as plutonium and uranium
• Attempt to create a superbug
• Bacterial mercuric reductase gene has been
  successfully incorporated into this microbe to
  enable it detoxify ionic mercury found in
  radioactive waste sites

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Anti-material

• The use of GEMs to create non-lethal weaponry
• Hydrocarbon loving bacteria in the natural
  environment can degrade asphalt, concrete,
  plastic, natural and synthetic rubber, composite
  materials, stone, and metals
• This is an extremely slow process in nature

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Anti-material

• These naturally occurring microbes are
  genetically modified to speed up the degradation
  process
• Ex there are several microbes able to degrade
  2,4,6-trinitotoluene (TNT), and if genetically
  modified can cause the TNT to lose 50 of its
  explosiveness every 7 days
• These GEMs can also be used to degrade
  lubricants in fuel systems or coatings on
  military aircraft and vehicles

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Anti-material

• Currently federally prohibited
• Violates BTWC rules
• suicide genes insertion into these microbes
• Attempt to make them more commercially viable
• http//www.sunshineproject.org/publications/bk/bk
  9en.html

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Activation

• Is bioremediation a fail-proof solution to
  contamination issues?
• No, mainly due to activation
• Activation- occurs when degrading organisms alter
  a substrate into a constituent that is equally or
  even more harmful than the parent substance
• Microbes can create pollutants from non-pollutant
  sources

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Activation

• Harmful products that may develop include
  neurotoxins, phytotoxins, mutagens, carcinogens,
  and teratogens
• Ex biodegradation of TCE (industrial solvent) in
  contaminated aquifers can produce vinyl chloride,
  a harmful carcinogen
• Cl2CCHCl?ClCHCH2

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Activation

• Activation can sometimes be prevented by being
  aware of the metabolic pathways of microorganism
• This is done by diffusing, or creating products
  that have alternative metabolic pathways in
  microorganisms

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Conclusion

• Bioremediation is not the solution for all toxic
  waste contamination
• Should be selected for use in sights that are
  most compatible and will produce the best
  outcomes
• Pesticides and oil spills are well suited because
  of the hydrocarbons that are present

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Conclusion

• It is important to note that the acclimation
  phase of microorganisms to a contaminant may
  allow the contaminant to spread to distant areas
• Bioremediation is another asset that should be
  used in conjunction with other remediation
  techniques