J. Tony Pembroke, Balakrishnan Naveena and Patricia Armshaw

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/60514

#### **Abstract**

The photoautotrophic cyanobacterium *Synechocystis* PCC6803 has received much attention as a model photosynthetic cell factory for the production of a range of important biotech products. The biomass remaining from this activity may then have further utility in processes such as metal bioremediation. In addition *Synechocystis* being an inhabitant of many natural aquatic environments is seen as an environmen‐ tally friendly alternative to using chemical precipitation methodologies for metal remediation. *Synechocystis* produces a range of extracellular polysaccharide substan‐ ces (EPS) that can undergo modification as a function of culture age and growth nutrients which have been implicated in metal biosorption. Many studies have demonstrated that high levels of charged groups present in EPS are important in forming polymeric matrices with metallic ions allowing their biosorption. Genetic studies has revealed genes involved in such metal binding indicating that EPS can be modified for potential enhancement of binding or modification of the types of metals bound. The utility of metal binding to live and dead biomass of *Synechocystis* has been demonstrated for a range of metals including Cr(VI), Cd(II), Cu(II), Pb(II), Sb, Ni(II), Mn(II), Mn(IV), As(III), As(V), Cs and Hg. The potential of using *Synechocystis* as a biosorption platform is discussed.

**Keywords:** *Synechocystis*, EPS, metal biosorption, metal binding, metal remediation

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