Bacterial inoculant-assisted phytoremediation of heavy metal-contaminated soil: Inoculant development and the inoculation effects

Heavy metal contamination is a worldwide concern and a challenge to resolve due to the toxicity poses a significant threat to all living organisms in the environment. Phytoremediation is an environmental-friendly approach to alleviate heavy metal contamination in the soil. Combining the plant and beneficial bacteria inoculant to remediate soil heavy metal is known as bacterial inoculant-assisted phytoremediation. Beneficial bacteria facilitate plant metal uptake by mobilizing the heavy metals in the soil and enhancing plant vigor. The inoculant formulations can be prepared as liquid, granules or powders. Nonetheless, the effective interaction between plant and bacteria is not promised in unsterilized soil, thus affecting the phytoremediation efficiency. The development of bacterial inoculants for phytoremediation and the effects of the inoculants in soil are overlooked in current research studies. Therefore, an ample understanding of the bacterial inoculant-assisted phytoremediation concept is pertinent to circumvent the limitations. This article discusses the relationship between beneficial bacteria inoculant and plant in different techniques of phytoremediation, recent advances in developing bacterial inoculants for phytoremediation and the fate of the inoculants in soil. The provided information in this article generates more insights on the optimization works, which ultimately leading to the possible field application.