Phytoremediation of Trace Element–Contaminated Environments and the Potential of Endophytic Bacteria for Improving this Process

Abstract

Trace elements (heavy metals and metalloids) are among the most widespread contaminants that pose serious threat to all living organisms. Plant and microbial-assisted remediation holds great promise for in situ remediation of trace element–contaminated environments. An extended knowledge of plant processes generally involved in the uptake, translocation, storage, and detoxification of contaminants, and plant-microbe interactions were essential in developing improved technologies for environmental cleanup. Presently, with the initiation of transgenic technologies, great strides have been made in trace element phytoremediation research. In this review, the authors provide an overview of the present knowledge of how plants cope with trace elements and discuss the development of transgenic plants with improved trace element remediation capabilities. In addition, they also address the recent progress made toward understanding the plant-microbe interactions, especially of endophytic bacteria (natural and genetically engineered), and their contribution in improving the efficiency and versatility of trace element phytoremediation.

KEY WORDS:

• endophytes
• heavy metals
• metalloids
• overexpression
• phytoremediaton
• trace elements
• transgenic plants

ACKNOWLEDGMENTS

The financial support from FCT (SFRH/BPD/26837/2006) to Sam Cherian is gratefully acknowledged. Nele Weyens and Jaco Vangronsveld acknowledge the support of the UHasselt Methusalem project 08M03VGRJ.