A review on the functions of microorganisms in the phytoremediation of heavy metal-contaminated soils

Abstract

We have reviewed the current literature on plant-microorganism remediation systems for the treatment of heavy metal contaminated soils, including examples of applications developed or advanced in the past five years. In the bioremediation process, the plant-microorganism system performs two functions:metal immobilization and metal removal. Arbuscular mycorrhiza, symbiotic complexes between endophytes and plant root systems, can optimize the micro-environmental conditions for root development and enhance the ability of plants to tolerate metal toxicity, thus promoting both plant growth and metal uptake and transport. Establishment of a plant-microorganism coupling system can amplify the independent effects of the plant and the microorganism, thereby increasing the efficiency of phytoremediation. Investigation of the synergistic effects among plants, microorganisms, and their growth media will be an important topic of future study. The development of new technology requires that particular attention be given to the screening and replication of microorganisms suited to remediation of different types of heavy metal pollution.