Metal removal and recovery by bacteria-based biocomposites


Metal removal and recovery by bacteria-based biocomposites

Raff, J.

Bacteria are simply organized, but apart from that and their small size they are an unbelievable complex and a highly efficient group of creatures. Some are able to thrive at the most forbidding, uninviting places on Earth, for example in hot springs, in the perpetual ice, in the deep sea or in deserts. For production of energy they can use different kinds of organic and inorganic matter or sun light. Furthermore, they successfully conquer also any other habitats, even so an environment is highly contaminated with toxic substances, like organic solvents, heavy metals and radionuclides. Adaptation and detoxification mechanisms allow them to resist high concentrations of toxic elements without getting sustainably affected. These mechanisms are very prospective for the development of innovative remediation strategies and for other biotechnical applications [1-6].
Within the radio-ecological research on the interaction of bacteria with actinides many reference strains and isolates were investigated for their interaction with heavy metals and radionuclides [7-11]. The studied bacteria possess different strategies to handle high metal concentrations in their environment. Namely, via an immobilization of the metals by biosorption, bioaccumulation inside the cell, biomineralization and biotransformation. In principle, all mentioned strategies are suitable for the development of new materials for bioremediation techniques and the removal of metals. In respect of the development of metal selective and reusable filter materials, several Bacillus and Lysinibacillus isolates from a uranium mining waste pile were preferentially investigated. The cells bind selectively and reversibly uranium on their surface. Furthermore the analyses results in the identification of new so called surface layer (S-layer) proteins, forming the outermost structure on many bacteria. This S-layers are able to bind and detain toxic heavy metals while essential ones may pass. To take advantage of this intelligence intact cells, spores and the S-layer proteins of the bacteria were immobilized in sol-gel ceramics [11, 12] and used for metal binding experiments. Ongoing experiments include also the production of biofilm based materials and the protein immobilization on conventional carriers. Especially the S-layer proteins not only bind heavy metals very selectively but also some precious metals. The superior aim is the development of metal selective filter materials for the removal of heavy metals and in future for the recovery of precious metals from aqueous solutions.

Ackowledgements
We gratefully acknowledge support by the DFG (Biocere, SE 671/1-2) and the BMWi/PTJ (BIOREM, 03EGSSN014).

References
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[6] J. Raff and S. Selenska-Pobell (2006), Nuclear Engineering International 51(619) 34-36
[7] M. Merroun et al. (2005) Appl. Environ. Microbiol. 71(9): 5532-5543
[8] M. Merroun et al. (2006) Radiochimica Acta 94, 723-729
[9] H. Moll et al. (2008) BioMetals 21, 219-228
[10] H. Moll et al. (2006) Radiochimica Acta 94(2006), 815-824
[11] J. Raff et al. (2003), Chem. Mater. 15, 240-244
[12] K. Pollmann et al. (2006), Biotechn. Adv. 24 (1), 58-68

  • Lecture (Conference)
    Max Bergmann Symposium 08 on Molecular Designed Biological coatings, 04.-06.11.2008, Dresden, Deutschland

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Publ.-Id: 11659