Jonathan Lloyd

School of Earth, Atmospheric and Environmental Sciences

The University of Manchester

Geomicrobiology.co.uk

jon.lloyd@manchester.ac.uk

Land Bioremediation and Bionanotechnology

Industrial Uses of Bacteria19 May 2010 - IOM3, London

Plan• Introduction to “Geomicrobiology” & “Bionanotechnology”• Nanomaterials for remediation• Microbial iron cycling and the production of functional nanomaterials

– Bionanomagnetite production– Incorporation of trace elements; Co ferrites– Treatment of metals (Cr(VI)/Tc(VII))– Treatment of organics (azo dyes, nitrobenzene, TCE)– Novel, multifunctional catalysts with precious metal coatings

• Future research

Geomicrobiology

Microbial ecology

Microbial physiology

Biochemistry

Molecular biology

Systems biology

Geochemistry

Inorganic chemistry

Mineralogy

Isotope chemistry

Environmental/civilengineering

Biology Science / engineering

Geomicrobiology“The role microbes play or have played in geological processes”

Ehrlich, 1996

Physics Computation

Geomicrobiology

Includes•The origin of life•Life on other planets•The control of Earth’s chemistry•Environmental mobility of metals, radionuclides

and organics•Bioremediation•Bionanotechnology

Bionanotechnology

•Nanotechnology “engineering and manufacturing at nanometer scales,

with atomic precision”•Bionanotechnology “subset of nanotechnology; atomic level

engineering and manufacturing using biological precedents for

guidance”

Goodsell (2004) “Bionanotechnology: Lessons from Nature”

•Emphasis; vision of precision assembly of complex large-scale systems

incorporating biomolecular devices. Interfaces with “Synthetic Biology”

•Manchester Geomicrobiology Group has focused on engineering

biominerals to augment bioremediation potential of subsurface bacteria

Environmental nanotechnology

Environmental Bionanotechnology

Dissimilatory metal reduction

Focus of Manchester Geomicrobiology group• Mechanisms• Environmental impact• Biotechnological applications

Microbial metal reduction•Widely distributed through prokaryotic world•Transition metals, metalloids, actinides•Dissimilatory and resistance processes

Metal reduction; mechanisms•Electron transfer mechanisms in Fe(III)-reducing bacteria e.g. Geobacter

(proteins, genes, secreted mediators)•Mechanisms of reduction of trace elements and radionuclides•Development of molecular scale model for electron transfer to mineral surfaces

Metal reduction; environmental impact

From Islam et al. 2004 Nature 430 68-71

Mobilisation of As(III) by metal-reducing bacteria

Metal reduction; environmental impactBiogeochemistry of radionuclides

Organics or H2

CO2 and/orH2O

Soluble U(VI)

Insoluble U(IV)

e-

Drigg nuclear repository

Functional bionanominerals

•Bionano-ferrite spinels – ‘designer’ nanomagnets•Precious metal (Pd, Ag, Au) and Fe-based catalytic bionanoparticles•Bionano-chalcogenides - diluted magnetic semiconductors and quantum dots

Pd

Pd

Magnetite supportedBionano magnetite

catalyst

Why are magnetic nanoparticles important?

• magnetic data storage • catalysis• biosensors • drug delivery• cancer therapy• magnetic resonance imaging (MRI)• environmental remediation

Magnetite bioproduction

Geobacter sulfurreducens

Examples with trace metals added to system during or after magnetite production

Incorporation of trace elements

Bioengineering Co ferrites

X-ray Magnetic Circular Dichroism

• Element, site and symmetry selective ; quantitative information on site occupancies in magnetic minerals.

• Inverse spinel structure of magnetite is Fe3+[Fe2+Fe3+]O4 (see left). tet=tetrahedral, oct=octahedral site.

• Possible to substitute Fe2+ with other transition metals (and change the magnetic properties of the spinel)Octahedral sites Tetrahedral sites

Oxygen

Fe2+ Oct Fe3+ Tet Fe3+ Oct Tet[oct]

0.900 0.966 1.134 Fe0.97[Fe2.03]O4

Occupancies of Geobacter magnetite

Geobacter sulfurreducensCobalt-substituted magnetites