Harnessing the Duo Effect of Plant Growth-Promoting Rhizobacteria and Organic Amendments in the Phytoremediation of Cadmium: a Review

Cadmium (Cd) is considered as one of the potentially toxic elements (PTEs) with carcinogenic properties. Its presence in soil-water-plant systems can be attributed to both anthropogenic and natural processes. Harmful practices, including urban waste disposal, metal processing, smelting, mining, and industrial fertilizer manufacturing, contribute to the increasing concentration of Cd in the environment, posing a threat to human health. To address this issue, several remediation strategies have been implemented, including physicochemical and biological approaches. However, it is important to note that physical methods are often impractical for treating larger soil volumes, while chemical methods may result in secondary pollution due to the generation of by-products during the chemical Cd removal process. In contrast, the application of organic amendments and biological agents, such as plant growth-promoting rhizobacteria (PGPR), offers a more sustainable and cost-effective alternative. Moreover, their combined effects on the bioremediation of Cd- contaminated sites have demonstrated more promising outcomes, as reported by several researchers. This review paper aims to comprehensively discuss the sources of Cd pollution and its impacts on soil, water, plants, and human health. Additionally, it explores various remediation techniques using organic amendments and PGPR, with a particular emphasis on the synergistic effects of PGPR with organic amendments.