Rhizospheric bacteria: the key to sustainable heavy metal detoxification strategies

Abstract

The increasing rate of industrialization, anthropogenic, and geological activities have expedited the release of heavy metals (HMs) at higher concentration in environment. HM contamination resulting due to its persistent nature, injudicious use poses a potential threat by causing metal toxicities in humans and animals as well as severe damage to aquatic organisms. Bioremediation is an emerging and reliable solution for mitigation of these contaminants using rhizospheric microorganisms in an environmentally safe manner. The strategies are based on exploiting microbial metabolism and various approaches developed by plant growth promoting bacteria (PGPB) to minimize the toxicity concentration of HM at optimum levels for the environmental clean-up. Rhizospheric bacteria are employed for significant growth of plants in soil contaminated with HM. Exploitation of bacteria possessing plant-beneficial traits as well as metal detoxifying property is an economical and promising approach for bioremediation of HM. Microbial cells exhibit different mechanisms of HM resistance such as active transport, extra cellular barrier, extracellular and intracellular sequestration, and reduction of HM. Tolerance of HM in microorganisms may be chromosomal or plasmid originated. Proteins such as MerT and MerA of mer operon and czcCBA, ArsR, ArsA, ArsD, ArsB, and ArsC genes are responsible for metal detoxification in bacterial cell. This review gives insights about the potential of rhizospheric bacteria in HM removal from various polluted areas. In addition, it also gives deep insights about different mechanism of action expressed by microorganisms for HM detoxification. The dual-purpose use of biological agent as plant growth enhancement and remediation of HM contaminated site is the most significant future prospect of this article.

Biochar and organic fertilizer drive the bacterial community to improve the productivity and quality of Sophora tonkinensis in cadmium-contaminated soil

“…These could be ascribed to the direct release of nutrients from organic fertilizers and biochar ( Hussain et al, 2023 ). Furthermore, the improvements in available soil nutrients could be attributed to the high alkalinity and cation exchange capacity (CEC) of biochar ( Muhammad et al, 2018 ; Joshi et al, 2023 ; Xiao et al, 2023 ). Nevertheless, it is important to note that although BO treatment mitigated Cd accumulation in Sophora tissues, complete avoidance of Cd absorption was not achieved ( Table 3 ).…”

“…Typically, the activities of diverse soil enzymes, which are crucial for facilitating the circulation of matter and energy in the soil, are valuable indicators of soil health ( Yao et al, 2018 ; Chow and Pan, 2020 ; Yan et al, 2022 ; Joshi et al, 2023 ). Compared with the HM and FS groups, BO treatment significantly induced the activities of multiple soil enzymes, including catalase, polyphenol oxidase, and β-glucosidase ( Table 1 ).…”

Nanotechnology Approaches for the Remediation of Agricultural Polluted Soils

“…Rhizospheric bacteria, in addition to plants, play a critical role in the process of cleaning up contaminated environments. The same principles of phytoremediation that nature utilizes are employed by microorganisms and plants to decrease organic and inorganic contaminants . While previous studies have demonstrated the potential of nanophytoremediation of soil pollutants, newer dimensions emphasize a deeper understanding of uptake mechanisms, enhanced plant–microbe interactions, tailored nanoparticle design, multicontaminant remediation, green synthesis, field-scale applications, risk assessment, and community engagement.…”

“…The same principles of phytoremediation that nature utilizes are employed by microorganisms and plants to decrease organic and inorganic contaminants. 97 While previous studies have demonstrated the potential of nanophytoremediation of soil pollutants, 98 newer dimensions emphasize a deeper understanding of uptake mechanisms, enhanced plant–microbe interactions, tailored nanoparticle design, multicontaminant remediation, green synthesis, field-scale applications, risk assessment, and community engagement. These insights will contribute to the ongoing development of effective and sustainable nanophytoremediation strategies for diverse soil pollution challenges.…”

Bacterial Strategies for Improving the Yield, Quality, and Adaptability of Oil Crops

“…The cellular structure of PGPB enables it to capture heavy metal ions and absorb them at binding sites on the cell wall. Negatively charged sulfhydryl, carboxyl, hydroxyl, sulfonic, amino, and amide groups on the cell surface bind to positively charged HMs, fixing them onto the cell surface [229]. Some PGPB also produce biosurfactants, such as lipopeptide, subtilisin, and rhamnolipid, which form complexes with HMs [230].…”