Metals in Cyanobacteria: Physiological and Molecular Regulation

Abstract In recent days, the rapid development of industries and uncontrolled anthropogenic activities increased the concentration of various heavy metals in all types of environments, that is, aquatic as well as terrestrial/soil. Therefore, organisms thriving in such environments regularly face high metal concentrations which in turn adversely affect their growth and development. Among these organisms, cyanobacteria are very precious due to their tremendous ability to perform oxygenic photosynthesis. Apart from this, a number of cyanobacteria are well known to fix atmospheric N 2 and play important role in geochemical cycling of N 2 . In this chapter, we have provided information about the impact of heavy metals on the important physiological processes affecting biomass accumulation. We have also tried providing the strategies adapted at cellular (secretion of some chelates) as well as molecular (OMICS approach) levels by cyanobacteria to overcome the stress generated by heavy metals. However, there is still a dearth of knowledge related to mechanisms that help in establishing this tolerance/adaptation, most of the studies are being performed in plant system, while cyanobacterial system is still not much interrogated at the molecular level so that they can be used in several metal remediation programs. The future studies must utilize multidisciplinary approach including OMICS to establish the role of these cyanobacteria under heavy metal stress tolerance.