Plant-microbe Symbiosis as an Instrument for the Mobilization and Removal of Heavy Metals from Contaminated Soils – A Realistic Approach

摘要

Background: Contamination of soil with heavy metal is a major problem for developed and developingcountries. Therefore, different approaches including bioremediation has been applied for remediation ofmetal contaminated sites. Biological approaches offer efficient and better way to remediate pollution inthe air, soil and water. The plant-microbe interaction for remediation of polluted site is attracting interestsand attentions, due to its high effectiveness and low cost. Therefore, in this review, mechanisms involvedin removal of heavy metals like metal accumulation, enzymatic transformation and metal precipitation,and how plant-microbe interations can uplift the success rate of the process has been discussed.Approach of using plant-microbe interactions for the remediation of heavy metal contaminated soil,along with the roles of bacterial metabolites like siderophores, organic ligands and biosurfactants havebeen critically elaborated.Methods: A planned study was conducted for search of bibliographic databases of scientific studies ofheavy metal remediaton and plant-microbe interactions for bioremediation. The chracteristics of thescreened papers are described and the findings to conceptual framework critically analysed.Results: Different conventional methods have been used for remediation of heavy metals from contaminatedsites. But bioremediation using plant-microbe interactions seems to be efficient and low cost alternateto such conventional remediation technologies. Rhizoremediation performance is based on theinteractions of plant and microorganisms in the rhizoremediation. Rhizospheric microorganisms andtheir metabolites (e.g. siderophore, organic acids, IAA, etc.) have been suggested to be involved in (1)plant growth promotion through nutrient acquirement, alleviation of biotic/abiotic stress and (2) detoxificationof metals through altering its mobility and bioavailability.Conclusion: Although bioremediation through rhizosphere has been promoted as an effective techniquefor bioremediation of heavy metal contamination, yet its applications has not been exploited much, andthere is an urgent need to identify the lacunae to be addressed for success of this strategy.