Bioremediation Technology for Heavy Metal Pollution

Dr. Surasak SiripornadulsilDepartment of Microbiology,

Faculty of Science, Khon Kaen University

2Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

Environmental PollutantsType of Pollutant ExamplesInorganic

Metals Cd, Hg, Ag, Co, Pb, Cu, Cr, FeRadionuclideNitrates, nitrites, phosphatesCyanidesAsbestos

OrganicBiodegradable Sewage, domestic agricultural,

and process wastePetrochemical Oil, diesel, BTEXSynthetic Pesticides, organohalogens, PAHs

BiologicalPathogens Bacteria, viruses, molds

GaseousGases SO2, CO2, N2O, CH4Volatiles CFCs, VOCs

3

Environmental Remediation ChallengesIn USA

About 5,700 individual contaminant sitesAt Nevada Test site 1.5 million m3

At Fernald site 0.71 Km3

Savannah River site 7.8 Km3

Hanford site 18 Km3

Unknown quantities of buried waste at numerous sites.Costs $142 billion to locate and character contamination, restore, and dispose of wastes over the next 35 years.

In UKAbout 100,000 individual contaminant sitesCosts between £10,000 and £20,000 million to clean up.

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

4Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Arsenic in Ground-Water Resources of the United States

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

http://www.epa.gov/

6

Superfund sites in the United States

http://www.pollutionissues.com/

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Heavy Metalsa group of metals with density higher than 5.0 g/cm3

B C N O F Ne

He

Al Si P S Cl Ar

Se Br Kr

I Xe

At Rn

HLi Be

VNa Mg

K Ca Sc TiRb Sr YCs Ba La*

Ac**

Lanthanides*

Actinide**

Fr Ra Rf Db Sg Bh Hs Mt

Cr

Zr Nb Mo

Mn

Tc

Fe

Hf Ta W Re OsRu Rh

Co Ni Cu Zn Ga

PtIr

Pd Ag Cd InAu

Sb

As

SnGe

Hg Tl

Te

Lr

Lu

Bi

Gd Dy Er

PoPb

Tm YbTb Ho

MdFm NoEsCfBkCm

Ce Pr Nd PmPa Np Pu Am

Sm EuTh U

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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The global distribution of cadmium output in 2005 as a percentage of the top producer (China - 3,000 tonnes)

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

Cadmium output in 2005 shown as a percentage of the top producer (China)

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http://www.csr-asia.com/

Gold Peak, Cadmium and “Grey Babies”

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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The relative importance of various cadmium sources to human exposure (Van Assche, 1998)

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

www.jamesmbrown.co.uk/cd_pigments/green.htm

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EPA Maximum Contaminant Levels for Drinking Water

Metals PPB μMolarBarium 2,000.0 15.00Copper 1,300.0 21.00 Chromium 100.0 2.00Arsenic 50.0 0.60Selenium 50.0 0.60Lead 15.0 0.07 Cadmium 5.0 0.04Mercury 2.0 0.01Thallium 2.0 0.01Organics PPBBenzene 5.0Atrazine 3.0PCBs 0.5Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Toxic substances in the food chain(Bioaccumulation)

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Molecular Mechanisms of Heavy Metal Toxicity

• Replace essential metals in metalloenzymes

• Bind to sulfhydryl groups

• Facilitate formation of free radicals and reactive oxygen species

• Alter redox status of cells

• Interfere with essential metal uptake and transport

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Cadmium ToxicityCarcinogenDevelopmental ToxicantReproductive ToxicantCardiovascular or Blood ToxicantEndocrine ToxicantImmuno ToxicantKidney ToxicantNeuro ToxicantRespiratory Toxicant

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

15Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Heavy Metal Pollution in Thailand

11: Nakhon Si Thammarat (1986) Arsenic

2

2: Kanchanaburi (1998) Lead

3

3: Tak (2002) Cadmium

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Cd Contamination in Baan Pha Te, Mae Sot, Tak Province

Simmons, RW, et al. (2005) Environ. Geochem. & Health, 27: 501-511.

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Crop tissue Zn, Cd and Fe concentrations (mg/kg) and tissue Cd:Zn and Cd:Fe ratios

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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• Some trace metals are essential nutrients (e.g., copper, cobalt, etc.) and others are toxic (e.g., cadmium, lead, mercury).

• Trace metals are active in their elemental form or as salts.

• Trace metal pollutants can not be decomposed, unlike organic pollutants, but must be sequestered from the environment.

• Ideally, trace metal recovery should be selective without interference from other metals.

Impediments to Remediation of Trace Metal Contaminants

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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A Problem of the PastA Problem of the Past,,A Solution for the FutureA Solution for the Future

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

21Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

http://biogeochemistry.plantbiology.msu.edu

Biogeochemical Cycle

Microbes

Microbes

22

Bioremediation is the process of using naturally occurring plants and microbes to digest and convert

waste material into harmless substances.

Select a strategy of Bioremediation

Identify the problem

Develop a solution

Microbes and plants detoxify waste

Problem solved

Life Cycle of a pollution problem

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Bioremediation Strategies1. Use the indigenous microbial population.2. Stimulation of indigenous microbial growth.3. Bioaugmentation: the addition of adapted

or designed inoculants.4. Addition of genetically modified

microorganisms. 5. Phytoremediation.

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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ESSENTIAL FACTORS FOR MICROBIAL BIOREMEDIATION

Factor Desired Conditions• Microbial Suitable kinds of organisms that can biodegrade

population all of the contaminants• Oxygen Enough to support aerobic biodegradation

(about 2% oxygen in the gas phase or 0.4 mg/liter in the soil water)

• Water Soil moisture should be from 50–70% of the water holding capacity of the soil

• Nutrients Nitrogen, phosphorus, sulfur, and other nutrients to support good microbial growth

• Temperature Appropriate temperatures for microbial growth (0–40˚C)

• pH Best range is from 6.5 to 7.5

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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LIMITATIONS OF BIOREMEDIATION• Contaminant type and concentration• Environment• Soil type• Condition and proximity of groundwater• Nature of organism• Cost/benefit ratios: cost versus overall

environmental impact• Does not apply to all surface• Length of bioremediation process• Capabilities of bioremediation

26

Microbes effectively sequester heavy metals:• Microbes are the primary means of heavy metal

deposition in terrestrial/aquatic environments.• Tolerant of high heavy metal concentrations. • High heavy metal binding capacity. • Synthesize high-affinity, heavy metal binding proteins in

response to toxic heavy metal concentrations.• Bioimmobilization

Applications in terrestrial/aquatic environments:• Easily grown and harvested. • Unicellular, high surface to volume ratio.• Can be genetically engineered to potentially improve

metal recovery.

Microbes as Heavy Metal Remediation

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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1. Heavy Metal-Induced Gene Expression in Chlamydomonas

2. Expression of Plant “Stress Genes” in Transgenic Chlamydomonas: Their Effects on Heavy Metal Tolerance and Binding

3. Expression of Surface-Displayed Heavy Metal Binding Proteins: Their Effects on Heavy Metal Tolerance and Binding

4. Cadmium-Resistant Bacteria/ Cadmium Contaminated Soil

Research Programs

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Analysis of Early Cadmium-Induced Transcripts by Differential Display

• Cells exposed to 25 μM cadmium for two hours

• mRNA isolated from WT and cadmium exposed cells and reverse transcribed

• cDNA amplified using GC-biased sets of primers and products displayed on sequencing gel

• Cadmium induced transcripts confirmed by reverse northern blot analysis (3X)

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Representative Early, Cadmium-Induced Differential Display Result

No Cd 2-hr Exposureto 25 μM CdCl2

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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1. Thirteen non-redundant cadmium-induced cDNAsidentified by differential display.

2. Five cDNAs identifieda. psbA - D1 protein of PSIIb. chlL - Fe-S subunit of light-independent

protochlorophyllide reductasec. CHRSAMS - SAM synthetased. CRD1 - required for PSI assembly under copper

deficiency, Fe-protein?e. H43 – mostly highly induced by cadmium, encodes a

periplasmic protein involved in iron uptake.3. Two cDNAs present in Chlamydomonas EST library, one

is high-CO2 induced.4. Currently, six unidentified cDNAs.

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

Early Cadmium-Induced Genes in Chlamydomonas

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The Chlamydomonas H43 Gene Compliments Yeast fet3fet4 (low and high affinity iron uptake) Mutants.

Solid symbols: fet3fet4complemented with H43 gene

Open symbols: fet3fet4

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

Comparative Growth at Different Iron Concentrations (5-8 μM Fe+3)

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H43 Expression in WAT11 (WT S. cerevisiae) Does Not Confer Cadmium Sensitivity

WA

T11::pY

ES2 (3)

WA

T11 ::H

43 (1 ,3)

WA

T11::pY

ES2 (4)

WA

T11 :: H

4 3 (2 ,2)

WA

T11::pY

ES2 (3)

WA

T11 ::H

43 (1 ,3)

WA

T11::pY

ES2 (4)

WA

T11 ::H

43 ) ( 2,2 )

No Cd 100 μM Cd

10 –1 O.D.

10 –2 O.D.

10 –3 O.D.

Cell number

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Does H43 Transport both Iron and Cadmium or Just Iron?

Cell wall

Periplasmicspace

Plasmamembrane

Fe(III)

Fe(II)

H43

Fe(III) Fe(II)

ZIP

Cd H43 Cdferric reductase

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Conclusions• Several early cadmium-induced genes involved

in Fe metabolism.• Chlamydomonas H43 is a novel protein with a

role in iron uptake◘ H43 induced in response to relatively low cadmium

exposure and iron deficit implying competition between iron and cadmium uptake

◘ The H43 gene will be a useful tool in the study of metal homeostasis and may be utilized in the development of superior iron-acquiring crops

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1. Heavy Metal-Induced Gene Expression in Chlamydomonas

2. Expression of Plant “Stress Genes” in Transgenic Chlamydomonas: Their Effects on Heavy Metal Tolerance and Binding

3. Expression of Surface-Displayed Heavy Metal Binding Proteins: Their Effects on Heavy Metal Tolerance and Binding

4. Cadmium-Resistant Bacteria/ Cadmium Contaminated Soil

Research Programs

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

36

Expression of Plant “Stress Genes”in Transgenic Chlamydomonas:

Their Effects on Heavy Metal Binding and Tolerance

Over-expression of Proline

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Pyrroline 5 Carboxylate Synthetase (P5CS) Catalyzes a Rate-Limiting Step in Proline Synthesis

P5CS

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Southern/Western blot analysis of wild-type (CC-425) Chlamydominas and transformed cells

expressing foreign P5CS geneKb 1 2 3 4

14.88.8

5.4

4.33.8

2.42.2

Lane 1: Wild-type (CC-425)/KpnI Lane 2: P5CS-1/KpnI Lane 3: P5CS-2/KpnI Lane 4: P5CS-3)/KpnI

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

1 2 3 4 5 690

70

kD

P5CS trangenic W.T.

Lane 1: 10 mg protein of P5CS-1Lane 2: 15 mg protein of P5CS-1Lane 3: 20 mg protein of P5CS-1Lane 4: 10 mg protein of CC-425Lane 5: 15 mg protein of CC-425Lane 6: 20 mg protein of CC-425

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Growth of wild-type (CC-425) and transformed Chlamydomonas expressing the P5CS gene

0 μM Cd 100 μM CdDays of Growth

0 2 4 6 8 10

Abs

orba

nce

750

nm

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

W.T. P5CS-1 P5CS-2 P5CS-3-

Days of Growth0 2 4 6 8 10

Abs

orba

nce

750

nm0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6W.T. P5CS-1 P5CS-2 P5CS-3-

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Cadmium Binding Capacity of wild-type and transformed Chlamydomonas cells expressing

foreign P5CS gene

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1μg Cd/ Abs 750 nm

W.T.

P5CS-1

P5CS-2

P5CS-3

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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X-ray: electro-magnetic wave λ = 0.01 - 10 nm or Energy = 1100 eV - 100 KeV

Application of EXAFS :To obtain information about the arrangement of

atoms in locality of the absorbing atom.

The Useful Properties of EXAFS:1. Non-crystalline and crystalline solids can be treated

on the same basis.2. Structural information is obtained from EXASF by

a simple and direct analysis.3. The measurement is relatively easy and rapid.

EXAFS(Extended X-ray Absorption Fine Structure)

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Cd-ProlineComplex

Structure Model of Cadmium-PC Complex

S

S

SS

Cd

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

43Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

Siripornadulsil, et al. 2002. The Plant Cell. 14: 2837–2847.

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Cd K-edge EXAFS curve-fitting results for Cd-Chlamydomonas

Sample atom types N R(Å) σ2 (Å2) ΔΕ0 (eV)

W.T. (CC-425) Cd-O 1.15 2.2065 0.00389 4.953

Cd-S 1.40 2.5184 0.00208 4.953

P5CS-1 Cd-S 3.24 2.5000 0.00859 -0.574

N : Coordination number, R (Å) : Interatomic distance,σ2 (Å2) : Debye-Waller factor,ΔΕ0 (eV) : The difference of the resulting absorption energy

and the constant input in the FEFF8 calculation.

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Phytochelatin (PC) Synthesis

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Summary & Conclusion1. P5CS transformants have higher cytoplasmic

proline levels (1.8X) than wild-type cells.2. Expression of the P5CS gene enhances cadmium

tolerance (1.5X) and binding capacity (4.2X).3. Cadmium is coordinated predominantly by sulfur

in P5CS transformants (reduced sulfhydryl of phytochelatin).

4. Proline enhances cadmium tolerance by directly reacting to free radical as primary antioxidant, resulting the elevated GSH level. Then high level of GSH would presumably allow for increased PC synthesis.

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Cd2+ Cd2+

Glu + Cys γGluCys GSH PCsPC

synthaseGSH

synthetaseγ -GluCys

synthetase

Cd2+

sulfide

HMW CdS-PC complex

LMW Cd-PC complexs

Cd2+

Cd2+

vacuole

GS-Cd

Chloroplast, mitochondria,

ER

1O2, •OH1O2, •OH

1O2, •OH

GSSG

Cd2+

PCsPC

synthase

Cd2+

sulfide

HMW CdS-PC complex

LMW Cd-PC complexs

Cd2+

GS-Cd

Proline

+Proline + 3O2

Proline + nitroxideProline + peroxide

48

1. Heavy Metal-Induced Gene Expression in Chlamydomonas

2. Expression of Plant “Stress Genes” in Transgenic Chlamydomonas: Their Effects on Heavy Metal Tolerance and Binding

3. Expression of Surface-Displayed Heavy Metal Binding Proteins: Their Effects on Heavy Metal Tolerance and Binding

4. Cadmium-Resistant Bacteria/ Cadmium Contaminated Soil

Research Programs

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Metallothionein-II, α− and β−Domain Polymers Fused to a Periplasmic

Membrane Protein

Expression of Surface-Displayed Heavy Metal Binding Proteins: Their Effects on Heavy Metal

Tolerance and Binding

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Rabbit Metallothionein-II

α

β

51

Metallothionein-Plasma Membrane Fusion Proteins

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Cd K-edge EXAFS curve-fitting results for Cd-Chlamydomonas

Sample atom types N R(Å) σ2 (Å2) ΔΕ0 (eV)

W.T. (CC-2137) Cd-O 1.89 2.1926 0.00450 1.659Cd-S 1.29 2.5003 0.00211 1.659

W.T. (CC-425) Cd-O 1.15 2.2065 0.00389 4.953Cd-S 1.40 2.5184 0.00208 4.953

MT-9 Cd-S 3.60 2.5113 0.00778 -4.690AMT-11 Cd-S 3.41 2.5001 0.00797 -2.765BMT-5 Cd-S 3.52 2.5131 0.00799 -1.972

N : Coordination number, R (Å) : Interatomic distance,σ2 (Å2) : Debye-Waller factor,ΔΕ0 (eV) : The difference of the resulting absorption energy

and the constant input in the FEFF8 calculation.Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

53

Summary & Conclusion1. Cytoplasmic expression of MT-II increases cadmium

tolerance (2X, at 40 mM CdCl2) but does not increase cadmium binding.

2. Expression of membrane anchored, periplasmic MT-II enhances cadmium tolerance (2.3X, at 100 mM CdCl2 ) and binding capacity per cell (5.1X for dimer).

3. Expression of periplasmic MT-II beta domain enhances cadmium tolerance (2.7X , at 100 mM CdCl2 ) and binding capacity per cell (4.4X for trimer).

4. Expression of periplasmic MT-II alpha domain enhances cadmium tolerance (1.6X , at 100 mM CdCl2 ) and binding capacity (4.1X for pentamer).

5. Cadmium is coordinated by sulfur in MT-II expressing cells (metallothionein cysteinyl sulfurs).

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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1. Heavy Metal-Induced Gene Expression in Chlamydomonas

2. Expression of Plant “Stress Genes” in Transgenic Chlamydomonas: Their Effects on Heavy Metal Tolerance and Binding

3. Expression of Surface-Displayed Heavy Metal Binding Proteins: Their Effects on Heavy Metal Tolerance and Binding

4. Cadmium-Resistant Bacteria/ Cadmium Contaminated Soil

Research Programs

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Cadmium-Resistant Bacteria/ Cadmium Contaminated Soil

Research in Progress

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Cd Contamination in Baan Pha Te, Mae Sot, Tak Province

Simmons, RW, et al. (2005) Environ. Geochem. & Health, 27: 501-511.

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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X-ray: electro-magnetic wave λ = 0.01 - 10 nm or Energy = 1100 eV - 100 KeV

Application of EXAFS :1. To obtain information about vacant orbital, electronic

configuration and site symmetry of the absorbing atom. 2. To obtain information on the oxidation state of the

cadmium atom as well as the geometrical arrangement of the atoms surrounding the absorbing atom.

The Useful Properties of XANES:1. Non-crystalline and crystalline solids can be treated on

the same basis.2. Structural information is obtained from XANES by a

simple and direct analysis.3. The measurement is relatively easy and rapid.

XANES(X-ray Absorption Near Edeg Structure)

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

234

8834

9735

0735

1635

2635

3535

4435

5435

6335

7335

8235

9136

0136

10

Energy (eV)

Nor

mal

ized

Abs

orpt

ion

Cd(NO3)2.4H2O

CdO

CdS

S1-1

S3-2

S5-2

TS2-1

TS4-1

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

Cadmium LIII-edge XANES3538 eV 3608 eV

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Cadmium-Resistant Bacteria

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Growth of Cadmium-Resistant Bacteria

0

0.5

1

1.5

2

2.5

0 3 6 9 12 15 18 21 24 30 36

เวลา (ชม )

Abs

orba

nce

600

nm

S2500-1

S2500-2

S2500-3

S2500-4

S2500-5

S2500-6

S2500-7

S2500-8

S2500-9

S2500-10

S2500-11

No Cd

Abs

orba

nce

600

nm

hours

0

0.5

1

1.5

2

2.5

0 3 6 9 12 15 18 21 24 30 36

(ช )

Abs

orba

nce

600

nm

S2500-1

S2500-2

S2500-3

S2500-4

S2500-5

S2500-6

S2500-7

S2500-8

S2500-9

S2500-10

S2500-11

Abs

orba

nce

600

nm

hours

500 μM Cd

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Cd Binding capacity of Cd-Resistant Bacteria

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

0

12

3

45

6

7

89

10

S2500-1S2500-2S2500-3S2500-4S2500-5S2500-6S2500-7S2500-8S2500-9S2500-10

S2500-11

S2500-12

S2500-13

S2500-14

S2500-15

S2500-16

S2500-17

S2500-18

S2500-19

S2500-20

S2500-21

S2500-22

S2500-23

S2500-24

Isolates

Log

[Cd(

atom

)]/C

ell

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Analysis of S K-edge XANES spectrum of Klebsiella planticola Strain (Cd-1)

2472 eV

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

Sharma, et al. 2000. Appl. Environ. Microbiol. 66: 3083–3087.

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Biotransformation

Heather AW and Tamar B. (2005) Current Opinion in Biotechnology. 16:261–268.

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Biotransformation

Fe(III), SO4-

Fe(II), H2S

e-

Electrons from organic C (lactate, acetate, ethanol) or H2

Metal reducing bacterium

Indirect reductive precipitation

U(VI), Cr(VI)Soluble, mobile

toxic

U(IV), Cr(III)Insoluble,immobileless toxic

Ox

Red Ox Red

Useful in above-ground and in situ treatments

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Direct reductive precipitation

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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Wells at old Rifle mine inject acetate (vinegar) into the ground to stimulate the growth of

microbes already in the soil.

http://www.genomenewsnetwork.org/articles/12_03/geobacter.shtml

Thai-Chinese Joint Seminar on Phyto/ Bioremediation Technology 18 & 19 February 2008

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BIOTECNational Synchrotron Research Center Dr. Richard T. Sayre, Plant Biology (Ohio State University)Dr. Sam Traina, Natural Resources (University of California at Merced )Members of My LabDepartment of Microbiology, Faculty of Science, Khon Kaen University