Understanding biological Understanding biological uranium reductionuranium reduction

Sherilee PalmSherilee Palm

Energy Postgraduate Conference 2013Energy Postgraduate Conference 2013

Supervisor: Prof E. van HeerdenCo-supervisors: Errol Cason

Dr. D. Opperman

IntroductionIntroduction• Microbe – metal interactions:

• Systems

Bioaccumulation

Biomineralization

Biosorption

Bioreduction

(Beliaev et al., 2001)

IntroductionIntroduction

(Vaughan and Lloyd, 2011)

AimsAims

• Assess the microbial diversity of uranium and thorium contaminated water.

• Use metal-reducing bacteria as biocatalysts for uranium and thorium bioreduction.

• Use known genomes of metal reducers to elucidate metabolic capabilities.

DiversityDiversity

To understand how a biological process occurs, two routes can be followed:

Let the microorganism do the work

Assess the genome of the

microorganism to determine if it has

the correct tools to do the work.

Uranium reductionUranium reduction

U (IV)U (VI)

U(VI)– Mobile– Soluble– Toxic

• Mutagen & carcinogenic

U(IV) – Immobile– Insoluble– Less toxic

(Payne, 2005; Cason et al., 2012; Abdelouas et al., 2000)

Enzymatic U(VI) reductionEnzymatic U(VI) reductionThe Lovley Model:

(Lovley et al., 1993; Cason et al., 2012)

Peptide ABC transporter, peptide-binding protein

External electron transport External electron transport systemssystems

(Valocchi, 2011)

ConclusionsConclusions•Microbial encounters with metals in the environment are

inevitable, consequently microbes have developed defence

mechanisms against metal toxicity.

•A mechanistic understanding of uranium (and thorium)

bioreduction/biosorption could aid in devising an effective

and economically feasible bioremediation process for the

removal/separation of these metals.

AcknowledgementsAcknowledgements• University if the Free State

• Prof Esta van Heerden

• Extreme biochemistry

• NRF (SANHARP)

T: +27(0)51 401 9039 | malekemm@ufs.ac.za

Thank youDankie

¡graciasشكرا

DěkujiDankeGrazie

gratias ago vosKe a leboha

T: +27 (0)51 401 9897 palmsm@ufs4life.ac.za