IN THE NAME OF GOD University of Esfahan Department of

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IN THE NAME OF GOD

• University of Esfahan
• Department of Biology
• Microbial Biotechnology
• Professor Nahvi
• Semester (II) 1386 87

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Mineral Biotechnology

• Keivan Beheshti Maal
• May 2008

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List of contents

• History of mineral biotechnology
• Bioremediation
• Bioremediation removable materials
• In situ bioremediation
• Transformation of Heavy Metals
• Source of heavy metals
• Heavy metal environmental and economical impact
• Microbe heavy metal interactions
• Bioleaching
• Biosorption
• Enzymatic transformation
• Biomineralization
• Nuclear wastes

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History of mineral biotechnology

• 1954 Bryner, Oxidation of Iron pyrites and
  copper sulphide could by Thiobacillus spp.
• 1958 Zimmerley, the first patent for mineral
  biotechnology
• 1983 Groudev, remove of iron and silica from
  sands and bauxite ores by bacteria and fungi
• 1993 Ohmura, pyrite extraction by several
  bacteria
• 1997 Miller, use of mixed mesophilic bacteria
  for bioleaching plants
• 2001 Suzuki, Successful commercial
  metal-leaching processes
• (extraction of gold, copper uranium)

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Bioremediation

• Bioremediation is reclaiming or cleaning of
  contaminated sites using microbes or other
  organisms
• This entails the removal, degradation, or
  sequestering of pollutants toxic wastes

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Bioremediation removable materials

• Oil spills
• Waste water
• Plastics
• Chemicals
• Toxic Metals
• Oil /
  Wastewater Cleanup

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In situ bioremediation
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Transformation of Heavy Metals

• Heavy Metals are toxic to life
• Disease Causing (i.e cancer)
• To alleviate mans past mistakes
• Help Conserve habitable environment
• Ran out of Hole to dig for storage
• Contamination of water supply

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Sources of heavy metals in waste

• Mining
• Tailings
• Lead
• Plastics, fishing tools, batteries, cable
  sheeting
• Mercury
• Measurement and control devices
• Chromium
• Wood preservatives and pigments
• Nuclear Waste

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Heavy metals environmental impacts

• Lead
• Humans, slows nervous system
• Toxic to plant life
• Mercury
• Consumed in Fish Products, affects organs
• Cadmium
• Accumulates in kidneys
• Chromium
• Considered most toxic

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Heavy metals economical impacts

• Estimates of the current US market for metal
  bioremediation 200 B / year
• The market for the clean-up of radioactive
  contamination 140 B / year (2004)
• Current Techniques for Decontamination
• Ion exchange
• Electrodialysis
• Extraction Wells

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Metal-microbe interactions

• Bioleaching
• Biosorption
• Enzymatic Transformations
• Biomineralization

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Metal microbe interactions

• Microbe assistance in mining for years
• Low-grade ore and mine tailings are exploited
• biologically
• Zinc, copper, nickel, cobalt, iron, tungsten,
  lead
• (sulfide water
  insoluble)
• Conversion of sulfide to sulfate by M.O
• Leach out of the sulfates from ore / extraction

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Cu2S not soluble CuSO4 is soluble
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Metal microbe interactions

• Bioleaching
• conversion of insoluble metals to solubilize
  
• metal by microorganisms
• Adventages
• - More cost effective
• - Low energy usage
• - Good function of M.O at low metal concentration
• - Harmless emissions
• - Reduced pollution in wastes

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Metal microbe interactions

• Important mineral-decomposing M.Os
• 1) Iron - oxidizing chemolithotrophs
• 2) Sulphur oxidizing chemolithotrophs
• E source inorganic chemicals
• C source CO2
• (hydrogen, sulphur, iron-reducing bacteria /
  archaea)
• Metal-leaching microorganisms
• use ferrous iron and reduced sulphur compounds as
  electron donors / CO2 fixation
• Produce sulphuric acid (acidophiles)

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Thiobacillus - SRBs

• Highly specialized autotrophic bacterium
• Acidophile
• Iron oxidizer
• Fe2 ? Fe3 e-
• Electron acceptor O2
• Versatile oxidizes sulfur, iron, copper..
• oxidation of S0 generates sulfuric acid
• SRBs
• Combined with Thiobacillus
• 2nd step reverses metal mobilization
• Form insoluble metal sulfides
• Acid-mine drainage cleanup

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Commercial Bioleaching Tanks
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Biosorption

• Metabolism-independent sorption of heavy metals
  to biomass
• Negative charge at cell surface / metal-binding
  proteins
• Low cost
• Molecular biology tools
• targeting engineered metal-binding proteins to
  cell surface

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Enzyme-Catalyzed Transformations

• Using enzymes from microorganisms to help treat
  metal contamination
• Examples
• Metal precipitation
• Redox transformations
• Useing high valence metals as electron acceptors
• (Fe3, Mn4, U6, Cr6, Se6, As5)
• Metal immobilization
• (c-type cytochromes)
• Geobacter and Desulfovibrio

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Geobacter

• Anaerobic
• Subsurface iron reducer
• Reduces Fe3 to Fe2
• Forms insoluble iron oxides
• Reduction of Uranium
• Electron donor acetate
• c3 cytochrome U(VI) reductase
• Uranium precipitated outside cell and in periplasm

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Desulfovibrio

• Sulfate reducer
• Reduction of uranium
• c3 cytochrome U(VI) reductase
• Extracellular precipitation of uraninite (UO2)
• Reduction of chromate
• Again c3 cytochrome Cr(VI) reductase

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Biomineralization

• Complete biodegradation of organic materials into
  inorganic constituents
• CO2 or H20
• SRBs
• Citrobacter
• Pseudomonas

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Biomineralization

• Iron-reducing bacteria
• Ex Tc(VII) reduced abiotically by magnetite
• (Precipitation of TcO2 by SRBs)
• Combined with Thiobacillus
• (Precipitation of Hg, Cr, U)
• Citrobacter
• Phosphate
• Degradation of glycerol 2-phosphate
• phosphatase enzyme
• Concentration of metal phosphates at cell surface
• (Precipitation of uranium and cadmium)

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Biomineralization

• Pseudomonas fluorescens
• Chromate
• constitutive, membrane-associated metallo-enzyme
• Tin (Sn)
• Secretion of soluble extracellular compound
• Pseudomonas syringae
• Copper
• periplasmic copper-binding proteins

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Nuclear Waste

• Current Treatment only by decay
• Storage Site away from civilization for Decay
• Leaking by Solublization into water
• Making heavy metals into insoluble form
• Bacteria precipitation of heavy metals
• Oxidized to a Reduced Form (less reactive)
• Uranium (Vi), Cr (VI) To U (IV) ,
  Cr (III)
• Indirect Reduction SO42- to H2S-
• Reduction of radioactive metal to insoluble state
  by H2S-
• Toxic effects ? low rate of bioremdiation in M.O

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Radio active contamination effects

• Nuclear waste
• 120 sites in 36 states that contain nuclear waste
• 475 billion gallons of contaminated groundwater
• 75 million cubic meters of contaminated sediment
• 3 million cubic meters of leaking waste

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RA elements half-life

• Radioactive element Half life (years)
• Sr 90 -------------------- 28
• Cs 137 -------------------- 30
• Pu 239 -------------------- 24100
• Tc 97 -------------------- 2.6 M
• U 238 ------------------- 4.5 B
• U 235 ------------------- 7.13 M

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Genetically Engineered Microbes

• Deinococcus radiodurans
• Radiation Resistant
• (up to 1.5 million rads)
• Bacillus infernos
• High temperature resistant
• Methanococcus jannaschii
• Pressure resistant (up to 230 atm)

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Treatable Heavy Metals

• Toxic Metals
• Uranium
• Chromium
• Selenium
• Lead (Pb)
• Technetium
• Mercury

• Other Metals
• Vanadium
• Molybdenum
• Copper
• Gold
• Silver

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Factors to be Considered

• Bioethics regarding Genetic Engineered Microbes
• Bioethics of Ecological Damage Control
• Cost / Tax Money
• Duration of Treatment to be effective

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Have a nice time
Bioremediation of the Alaska shorelines