Microbially-assisted phytoremediation toward air pollutants: Current trends and future directions

Plants, microbes, and their mutualistic associations are well known for degrading or removing harmful pollutants by various modes of remediation mechanisms in both the phyllosphere and the rhizosphere. When a specific plant species and microorganisms are introduced into a pollutant-rich environment, the associated microbes assist the plant to thrive while also reducing the level of pollutants. In recent years, various studies have been executed successfully on elucidating the underlying mechanisms of contaminant uptake and their degradation by plants and associated microbes. The reports suggested that size, molecular weight, hydrophobicity, lipid content, pH, electrolyte type, dissolved organic carbon, and molecular charge are the primary factors that influence the absorp-tion and transport of contaminants into plant tissues. Further, the absorbed pollutants are neutralized by various degrading enzymes and converted into nontoxic volatile form and released into the environment. Also, the efficiency of phytoremediation could be improved by using genetic engineering and gene editing technologies by transferring or altering genes involved in pollutant breakdown to plants. In this background, the review article provides comprehensive information on the existing literature and recent advances in the plant-microbe association system for the mitigation of several recalci-trant air pollutants. The review also discusses various pollutant uptake strategies and their degradation by various modes of phytoremediation mechanisms. The review also highlights the bottlenecks, challenges, sustainability, and future directions in this area of research. Whilst biotechnological and molecular approaches have the potential to improve microbially-assisted phytoremediation, they have yet to be extensively studied in the context of air pollution.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Plants, microbes, and their mutualistic associations can degrade or remove harmful pollutants in the environment. This review article provides comprehensive information on the mechanisms of contaminant uptake and degradation by plants and associated microbes. It also discusses the potential of genetic engineering and gene editing technologies for enhancing phytoremediation.